The 50 most-cited articles in Applied Mechanics and Materials, 2018

Friction welding of stainless steel to titanium with aluminum insert metal was investigated to improve the mechanical properties of the joints. Two different methods were used to insert the aluminum as a barrier between to substrates. The process parameters were found to be different for these two methods to obtain the sound welds. The friction welds between stainless steel and titanium with aluminum insert prevented the formation of brittle intermetallic compounds in the weld interface. A new intermetallic compounds such as AlTi and Al3Ti were formed between titanium and aluminum insert metal interface which are more ductile than the FeTi and CrTi intermetallic compounds. The joints characterized that the aluminum insert metal improved the metallurgical reaction at the weld interfaces thus indicates the results of decrease in microhardness of the intermetallic compounds which have major influence on the strength of the joints. The tensile strength of the aluminum insert welds was higher than the direct joints between the stainless steel and titanium. Higher tensile properties were…

In the present study commercially pure magnesium and aluminum strips were fabricated using the process of accumulative roll bonding. It is a prominent solid state joining process to manufacture similar and dissimilar materials for various applications. Three layers of stack was used for bonding of multilayered composite and preheated at 250 °C for 20 min. The effects of rolling parameters on bond strength and deformation of the strips were analyzed. The interface between aluminum and magnesium were characterized to identify the formation of diffusion compounds, and are found to be the presence of Al12Mg17 intermetallic compounds. Tensile strength of the bonds was increased with the decreasing of thickness of the strips. The interface characteristics were analyzed using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDAX) to reveal the intermetallic compounds, micro cracks and bonding properties. The strength of the composites is varying with width of the intermediate strip and maximum strength values were obtained after three passes of the roll bonding.

A 6061-T6 aluminium alloy was friction stir welded in submerged water as well as in air cool at a constant traverse speed and different rotational speed in order to investigate the microstructural characterization and mechanical behaviour of the joints. In order to improve the tensile strength of the joints, weldments were studied at different heat treatment processes such as post weld aged condition and solutionized condition. It is observed that, water cooled joints are resulted in enhancing of both strength and ductility with the lower strain hardening ability than the air cooled joints. The width of the hardness distribution varies with the different cooling process of the joints. The highest hardness peak observed to be located in the heat affected zone of the joints. The maximum tensile strength of the joints achieved for welds under water cooled conditions in contrast to air cooled conditions. Moreover, a combination of water cooling and post weld ageing is proven to be the optimal path to improving the microstructural and mechanical properties of the joints with a maximum…

Recently various types of sandwich panel are applied for constructing bridge and ship structures. Sandwich panel is material that consists of lightweight core material and two metal faceplates. The application of sandwich panel in ship structures makes the structure less-complex and ship’s selfweight lighter because of the reduction of secondary stiffeners. This paper discusses sandwich panel that was fabricated using synthetic resin core material and two steel faceplates. This study is aimed to analyze stresses developed in the sandwich panel of 750 GT Ro-Ro ship car deck structure when it was subjected to the deck design load. The finite element analysis was carried out to obtain the stress distribution and maximum deformation on the car deck structures. The stress of the ship car deck constructed using conventional steel structure, i.e. steel plate and stiffener, was compared with the stress of the deck that was built using sandwich panel.

Resilience as a concept has found its way into different disciplines to describe the ability of an individual or system to withstand and adapt to changes in its environment. In this paper, we provide an overview of the concept in different communities and extend it to the area of mechanical engineering. Furthermore, we present metrics to measure resilience in technical systems and illustrate them by applying them to load-carrying structures. By giving application examples from the Collaborative Research Centre (CRC) 805, we show how the concept of resilience can be used to control uncertainty during different stages of product life.

Ride comfort is a reference point in evaluating the dynamic performance in railway vehicles. There are more methods to assess the ride comfort, depending on the traffic details and the specific needs of a railway administration. This paper focuses on the comfort index methods, in accordance with UIC Leaflet 513 R and the standard of railway applications ENV 12299, and the ride Sperling’s method, formulated by Sperling. A correlation is drawn between the comfort indices corresponding to the two methods, based on the link between the comfort and the values of these indices. The comfort indices derived from the two methods by numerical simulations help with validating the fact that, in general, the velocity influences the vertical ride comfort, and, in particular, the position of the carbody critical points, from the perspective of the ride comfort.

In this work, a Material removal rate (MRR), Tool wear rate (TWR), Radial and overcut (ROC), a study on the die-sinking Electrical discharge machining (EDM) of Al-LM6/SiC/B4C hybrid composites has been carried out. The selection of above-mentioned hybrid composite was made considering its widespread application in aerospace, automotive, defense, biomedical and marine industries, due to its light weight and higher mechanical properties. This experiment was made only for the finish stage and has been carried out on the influence of four design factors: composition, discharge current (Ip), Pulse-on-time (Ton), Radial overcut (ROC) and Duty factors (Tau), over the previously mentioned, responded variables. This has been done by means of the method of design of experiment (DOE) which allows us to carry out the above-mentioned analysis performing a relatively small number of experiments. The study indicates that when discharge current (Ip) increases, Material removal rate increased. In the case of Tool wear rate the most influencing factor is discharge current, then pulse on time. In…

Population density and automation is the main reason for the demand of drinking water. Water purification without affecting an ecosystem is the important need for daily life. Desalination is the best and effective way to satisfy the demand of fresh water. It is the most effective application of the solar energy. There are many conventional and non-conventional techniques available to make drinking water from the saline water. Among these solar desalination proves to be both economical and eco-friendly system particularly for rural areas. Solar stills are simple device which is used to provide pure water from the saline water by the principle of evaporation and condensation. This article reviews on the several research done on the solar stills to enhance productivity. Different designs of solar still and energy storage materials have been used to increase the yield and also this study proved the fact that efficiency of the solar still is majorly influenced by design and operating parameters.

This paper addresses the problem of efficiently operating a flexible manufacturing machine in an electricity micro-grid featuring a high volatility of electricity prices. The problem of finding the optimal control policy is formulated as a sequential decision making problem under uncertainty where, at every time step the uncertainty comes from the lack of knowledge about fu-ture electricity consumption and future weather dependent energy prices. We propose to address this problem using deep reinforcement learning. To this purpose, we designed a deep learning architecture to forecast the load profile of future manufacturing schedule from past production time series. Combined with the forecast of future energy prices, the reinforcement-learning algorithm is trained to perform an online optimization of the production ma-chine in order to reduce the long-term energy costs. The concept is empirical-ly validated on a flexible production machine, where the machine speed can be optimized during the production.

Powerful permanent magnets are of essential meaning for electric drives as well as for environmental friendly energy conversion in general. The main requirements for these applications are high energy products, coercivity and remanent polarization, thermal stability as well as affordable price. As state of the art, rare earth permanent magnets, frequently consisting of NdFeB based alloys, meet these requirements. When complex geometric shapes like arcs, shells or freeform surfaces are required by the application, a trade-off has to be taken into account between magnetic performance and post magnet-fabrication processing steps. Either bonded magnets can be produced with great variety of geometries while accepting low magnetic performance due to a significant amount of nonmagnetic plastic binder matrix, or sintered blocks with great magnetic performance have to be machined out to the specified shape accepting great effort for grinding or wire cutting as well as a significant loss of valuable material. To overcome the drawback of both conventional established magnet manufacturing…

Human factors is playing an important role in every accident, particularly marine accidents. Hence, a lot of researches were conducted to analyze the human factors involvement in the accidents. Since the development of marine industry shows progressively increasing nowadays, especially in Indonesia, as Indonesia vision to be a global maritime axis of the world for marine industry, the awareness of safety life at sea has to be increase as well. Human reliability analysis (HRA) consist of many methodologies to analyze the accidents, the basic steps of HRA is qualitative method and quantitative method, one of the HRA methodology is Human Error Assessment and Reduction Technique (HEART) methodology which has been established in 1982 to assess nuclear power plant. HEART methodology is applied in this study to analyze the cause of marine accidents by human factors. The aims of this study are to know the main cause of accidents by human factors, to increase the awareness of safety at sea especially, and furthermore to improve the quality of ergonomics at sea. There are 93 EPC which…

In order to improve the vibratory roller ride comfort, a multi-objective optimization method based on the improved genetic algorithm NSGA-II is proposed to optimize the design parameters of cab’s isolation system when vehicle operates under the different conditions. To achieve this goal, 3D nonlinear dynamic model of a single drum vibratory roller was developed based on the analysis of the interaction between vibratory roller and soil. The weighted r.m.s acceleration responses of the vertical driver’s seat, pitch and roll angle of the cab are chosen as the objective functions. The optimal design parameters of cab’s isolation system are indentified based on a combination of the vehicle nonlinear dynamic model of Matlab/Simulink and the NSGA - II genetic algorithm method. The results indicate that three objective function values are reduced significantly to improve vehicle ride comfort.

Fly ash based geopolymer normally gets the optimum strength by heat curing. This is considered as a hindrance to in-situ applications. Therefore, development of fly ash based geopolymer that suitable for ambient curing will widen the application to the concrete structure. This paper reports the results of an experimental study on setting time and development of compressive strength of class C fly ash based geopolymer paste produced in ambient curing condition. The main synthesis parameters such as water to the geopolymer solid ratio, alkali to cementitious ratio and molarity of NaOH were varied to understand their individual effect on setting time and the mechanical properties of the resulting geopolymer. The results suggested that generally the setting time increased with the NaOH molarity and the compressive strength of 59 MPa was obtained for geopolymer mixture cured at ambient temperature for 28 days with alkali to a cementitious ratio of 0.35 and 10 M NaOH. The results will be useful for developing the knowledge of the use of high calcium fly ash in producing geopolymer. This…

Composite materials play a vital role in many industrial applications. Researchers are working on fabrication of new composite materials worldwide to enhance the applicability of these materials. The present study aimed to investigate the effect of Nano clay loading as filler on the mechanical properties of the bamboo fiber yarn reinforced polyester composite. Five different types of composite specimen were prepared with Nano clay loadings of 0 to 4 % weight fraction using hand lay-up technique. It was observed that the composite sheet with 1 wt % nano clay content exhibited the optimized tensile and flexural strength. However the mechanical properties tend to decrease with addition of nano clay content from 2 to 4 wt %. In spite of that the values of mechanical properties with 2 and 3 wt % nano clay content is higher than 0 wt % nano clay content.

A facile co-precipitation method was established for synthesis of mesoporous iron-manganese magnetic bimetal oxide (MIMO) and its adsorption property was studied for removal of toxic metal ion hexavalent chromium from aqueous solution. XRD pattern of MIMO confirms the existence of Fe2O3 and Mn3O4 particle, out of which Mn3O4 is ferrimagnetic in nature. Synthesized MIMO has shown high saturation magnetization (23.08 emu/g), high BET surface area (178.27 m2/g) and high pore volume (0.484 cm3/g), which makes it a potential adsorbent. Adsorption process followed second order kinetic and Langmuir isotherm model. Involvement of intra-particle diffusion is also confirmed from kinetic data, which can be attributed to the mesoporous nature of the MIMO. Cr(VI) adsorption shows high pH dependency and maximum adsorption capacity of 116.25 mg/g is reported at pH 2.0. Electrostatic attraction between anionic chromium species and protonated MIMO surface is the predominant mechanism in this adsorption process.

Roads are the most important component for the economic and social development of any country. India has a total road network of more than 6 million kilometers, which carry around 90% of passenger traffic and 65% of freight traffic. More than 20% land area of India is covered with soils having low California bearing ratio (CBR) and shear strength values. The pavement constructed over such soils will lead to rapid increase in construction and maintenance costs. This study presents a laboratory investigation about the combined effect of geotextile and geogrid reinforcement, placed in layers at various depths from top of specimen, on the strength behaviour of poor subgrade soil. Heavy compaction, soaked CBR and unconfined compressive strength (UCS) tests are conducted. The test results indicate significant improvement in CBR and UCS values for all geosynthetic reinforced cases, whereas ductility and rupture strength remains almost constant as compared to virgin soil. Scanning electron microscopy (SEM) analysis shows significant bonding between soil particles and fibers of geogrid,…

The intelligent monitoring and warning system in highway fog section can realize timely forecast, early warning and information integration in low visibility condition. It can supply the scientific basis to highway decision-making management and technology to establish highway intelligent transportation system. The self-developed intelligent monitoring and warning system includes vehicle detector, camera, variable information board, ZigBee modules and controller EUC. The system can greatly reduce the traffic accidents caused by fog. Result shows that the system has high precision and reliability.

Surface modification of activated carbon (AC) could be done through different methods in order to modify their specific physical and chemical properties to facilitate metals removal from wastewater. Three methods were used to modify the rice husk AC (RHAC) including the use of (1) HNO3, (2) dithizone and (3) the combination of HNO3 with dithizone. These modification agents were increased its affinity towards the desired pollutant. The modification methods demonstrated the effective process for the metal ions adsorption capability and the removal of them from water. For Ni2+ and Cd2+ adsorption, RHAC was modified by HNO3 giving the best adsorption capacity in comparison with using dithizone or the combination of HNO3 with dithizone. That adsorption was reached 17.23 mg/g for Ni2+ and 29.61 mg/g for Cd2+. Additionally, the surface area, which was characterized by BET (Brunauer–Emmett–Teller) of RHAC, was 710.8 m2/g and DA micropore volume was 0.447 (cm3/g). Especially, the only modified RHACs had the peak of N-H functional group by using Fourier transform infrared spectrum (FTIR).…

The characteristics of the lateral nonlinear vibration in composite shaft-disk rotor system with nonlinear deformation are studied. Firstly, the equations of the kinetic energy of the composite shaft, the disk and the eccentric mass as well as the equations of the strain energy of the composite shaft are derived. Based on these equations, the nonlinear vibration equations are deduced by using the Lagrange equation. Then, the frequency response curves and time response curves of the system are obtained by using the IHB method and verified by the fourth order Runge-Kutta method. Experimental results show that the external damping coefficient, the size of eccentric mass only influences the nonlinear amplitude. Moreover, the ply-angle, thickness to diameter(T/D) ratio, length to diameter (L/D) ratio, and the position of disk in the shaft not only produce an effect on the nonlinear amplitude, but also influence the nonlinear vibration frequency.

Temperature sensors are widely used in different industrial and scientific applications. These sensors commercially available in various type and configurations allow the enhancement of automotive systems. The manufactures need to improve and upgrade the technology by research activities regarding the accuracy of temperature measuring using sensors. In this paper will analyze the trends, applications and technologies in automotive temperature sensors. PTC/NTC thermistors are measured and characteristics curves are determined as expression of mathematical functions.

A study has been conducted to investigate the potential use of mengkuang leaves or Pandanus atrocarpus bonded with epoxy resin as external strengthening material for the strengthening of reinforced concrete (RC) beams. Physical and mechanical properties as well as structural properties of the mengkuang leaves-epoxy composite plates (MLECP) were evaluated in this study. Chemical treatment was performed on the dried mengkuang leaves using sodium hydroxide (NaOH) with concentrations of 2%, 5% and 8%. Scanning electron microscope (SEM) and flexural strength tests were conducted on the mengkuang leaves and flexural specimens, respectively. All the beams were tested to failure under four-point loading. Results showed that the flexural strength of the composite with 0.3 fiber volume ratio exhibited the highest flexural strength. Strengthening of RC beam using MLECP managed to increase the beam capacity.

In city, identification for 3 phase-4 wires power distribution lines is difficult due to compound installation of overhead and underground lines, transposition, bad view caused by trees or big buildings. It is necessary that the correct and fast identification method is required for load balancing among distribution lines. Tracing off-line method with high power impulse signal injection has been used recently. Our proposed method uses to identify live lines with very small power high frequency signal injection based on data communication technology. Two end communication terminals are required to be synchronized between them for determination on electrically same phases. Challenging issue is to achieve synchronization without GPS providing synchronizing time. A novel power transformer and phase identification system is designed and implemented. The system consists of a transmitter and a receiver with power-line communication module. Some experiments are conducted to verify the theoretical concepts in a big commercial building.

In order, to understand the problems, which occur during the dentistry simulations, it was highly important to be acquainted with the anatomy of the human skull skeleton, the way these bone components are working together to achieve a normal functionality. In this respect CAD parametric software has been used as it allows to define models with a high degree of difficulty. First, the main bone components were defined by using CT images. These images were then transferred to a CAD software using different methods and techniques. These models were completed in SolidWorks where, step by step, the virtual model of the studied bone system has been defined. Using the direct measurement method on some skull components the virtual bone base elements were generated. Then, the virtual models were exported to a software for FEA simulation and prepared for every dentistry simulations. These models were tested and was generated the finite elements structure. In the end of the paper, were extracted interesting conclusions.

High strength, low density, good corrosion resistance and biocompatibility is the combination of properties that Ti and its alloys can provide for engineering applications. Its costs are the most important limiting factor for the widespread use of Ti. Cost reduction for Ti alloys can derive from the use of cheaper alloying elements as well as the use of alternative manufacturing techniques. In this study binary Ti-X alloys (where X = Cu or Mn) were formulated and produced using the conventional powder metallurgy route of pressing and sintering. These chemical elements were selected because they are β stabilisers and can be used to create α+β Ti alloys. The study shows that with the techniques and processing parameters used handable products without delamination can be pressed. Moreover, chemically homogenous materials with density and mechanical property values comparable to those of other wrought-equivalent Ti alloys produced via powder metallurgy were achieved.

The purpose of this study is to select the appropriate high quality-strong-durable type of glue for bamboo laminated composite to substitute Teak wood as an alternative material for fishing boat construction. Tape Test and Pull Off Test according to ASTM D3359 and ASTM D4541 are applied on substrates of Betung laminated bamboo (Dendrocalamus Asper species) in order to determine the strength level of adhesiveness. Four types of glue are applied to bamboo laminated substrate. Having analyzed the experiment results, it indicates that Epoxy Polyamide has the highest adhesion value comparing to others. The Tape Test grades for Epoxy Polyamide are 5A (no glue peeling) and 5B (0% glue chipped extension) as well as the score of Pull Off Test is 7.92 MPa. In terms of construction cost for building fishing boat 20GT (laminated bamboo) using epoxy polyamide is a half compared to Teak wood material.

Advances in agricultural automation, coupled with a general decline of available labour hasgenerated interest in automated harvesting of various crops. Paramount to the success of such systemsis the development of accurate, robust detection technologies and localization strategies. This paperpresents an overview of sensor technologies used in the detection and localization of green aspara-gus spears for robotic harvesting. Tactile, photoelectric, machine vision and time-of-flight sensors areinvestigated and their applicability for use in robotic asparagus harvesting is evaluated. Investigationof previous asparagus harvesting devices has revealed that no such device has yet achieved commer-cial viability. It was identified that this is likely due to weaknesses in currently employed detectiontechnologies, namely slow response times, high sensitivity to changes in ambient lighting conditionsand requirement for frequent manual calibration. Of the sensor technologies investigated it was foundthat time-of-flight cameras, such as the Microsoft Kinect V2 are the most feasible for the…

The paper researches the possibility to reduce the bending vibrations in the railway vehicle carbody and to improve the ride comfort via a new passive type method. This would involve the fitting of the vehicle with dampers, called anti-bending dampers, fixed to the longitudinal beams of a carbody underframe. The efficiency of this method is made visible in the results derived from numerical simulations developed on the basis of a rigid-flexible coupled vehicle model. The introduction of the anti-bending dampers is seen as a significant reduction in the bending vibration of the carbody. Similarly, a relevant improvement of the ride comfort at the centre of the carbody, at high velocities. This efficiency mainly depends on the damping constant of the anti-bending damper.

There are numerous levers and constraints affecting the sustainability of electric motors. While previous work mostly focuses on individual energy and resource efficiency potentials within single phases of the motor’s lifecycle, this paper summarizes sustainability aspects from three different perspectives, namely from the market, product and process view. The first part of this paper analyzes the electric motor market to emphasize the significance of this industry and to outline the importance of state-regulated efficiency classes. The second part provides an overview of the range of electric motor types and their sustainability characteristics. The third part contains an analysis of manufacturing processes in terms of energy and resource efficiency by pointing out appropriate key figures and optimization approaches. In doing so, the connection of the three perspectives market, product and processes offers a holistic view on sustainability aspects of electric motors.

In this research, molybdenum trioxide (MoO3) nanoflakes were synthesized by a simple and low cost hydrothermal method for gas sensing application. Sodium molybdate (Na2MoO4·2H2O) was used as the precursor. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). After hydrothermal process, the powders were showed amorphous phase. However, after annealing process the MoO3was observed as particles having the orthorhombic phase. The average particle sizes of MoO3nanoflakes were about 80 nm. The morphologies, cross section and elemental compositions of sensing films were analyzed by SEM and EDS line-scan mode analysis. From the SEM image revealed nanoflakes morphologies of MoO3and the thickness of MoO3sensing film was about 10 mm. The obtained sensing film can be used as the sensing device to fabricate composited gas sensors for detection of some environmental hazardous gas (including ethanol, carbon monoxide, hydrogen sulfide, sulfur dioxide, nitrogen oxide, and ammonia) will report in the next research.

In this study, the forging operations of gear has been modeled. This gear is a part which is manufactured with the help of hot forging industry for reduce the cost. The authors propose to reduce the initial billet volume of AISI 4340 steel for the forged through process optimization using the Finite Element (FE)method. The object of this research was to predict the effect of several parameters, such as effective stress, effective plastic strain, temperature and die contact, on the forming of the gear, utilizing computer simulation and experimental results. For this purpose, Solidworks CAD and Simufact Forming FE software were used for the modeling and analysis of the forging process. The billet volume and the preform design were predefined in order to reduce scrap by using preform type C. The experimental results showed that the initial billet volume was reduced at 32 %, which compared favorably with the simulation result of a 40 % reduction. The maximum preforming force of simulation result was diferent with the experiment result at 18 along with the maximum finishing force of…

Load-carrying systems often suffer from unexpected disruptions which can cause damages or system breakdowns if they were neglected during product development. In this context, unexpected disruptions summarize unpredictable load conditions, external disturbances or failures of system components and can be comprehended as uncertainties caused by nescience. While robust systems can cope with stochastic uncertainties, uncertainties caused by nescience can be controlled only by resilient load-carrying systems. This paper gives an overview of the characteristics of resilience as well as the time-dependent resilient behaviour of subsystems. Based on this, the adaptivity of subsystems is classified and can be distinguished between autonomous and externally induced adaption and the temporal horizon of adaption. The classification of adaptivity is explained using a simple example of a joint brake application.

Robot simulation has developed quickly in recent decades. Along with the development of computer science, a lot of simulation soft-wares have been created to perform many purposes such as studying kinematic, dynamic, and off-line program to avoid obstacle on manipulator robots. The main objective of this study is therefore to analyze kinematic, dynamic characteristics of an R-R robotic manipulator in order to control this robot. Newton-Euler method was used to calculate the torque acting on each joint of the robot. Then, a numerical model of the robot was established by a multi-body dynamics software to compare with the results obtained by Newton-Euler theory. After that, a feed-forward control system was created by RecurDyn/CoLink to control the end-effector of the robot following a desired trajectory. The results showed that this research can be used for efficient simulation of structural kinematics, dynamics as well as control of the real manipulator robot with the robot structure in a virtual environment.

This work was focused on evaluating the potential of bamboo powder modified with manganese oxide (MnO-BP) as a low-cost byproduct adsorbent for the adsorption of cadmium(II) ion. A batch method was carried out at room temperature and the optimized conditions. The optimization of adsorption parameters including pH, equilibrium time, dosage and initial Cd(II) concentration was also systematically studied for the removal of cadmium(II) ion. The maximum monolayer adsorption capacity of MnO-BP was estimated as 8.57 mg/g that it more adsorption capacity than untreated-bamboo powder by about 5 times. The Langmuir and the Freundlich isotherms were used to describe the adsorptive mechanism and calculated the maximum monolayer adsorption capacity. It was found that the data from MnO-BP fitted well to the Freundlich isotherm with R2>0.99. It indicated that the adsorptive behavior of MnO-BP to cadmium(II) ion is preferable. In this work, MnO-BP was used for the removal of cadmium(II) ion in wastewater sample. The MnO-BP is a low-cost adsorbent that can be used to remove cadmium(II) effectively.

Ti-5Al-2.5Sn alloy is widely used in aerospace applications due to its high specific strength, low coefficient of thermal expansion and good corrosion resistance. Presence of interstitial elements in the alloy has some significant effects on its properties. However the high notch toughness and cryogenic ductility attracts the usage of Ti-5Al-2.5Sn for usage at cryogenic temperatures even at 20K. For hydrogen embrittlement studies and for investigating notch sensitivity of Ti-5Al-2.5Sn alloy, the notched and smooth specimens from ELI grade of Ti-5Al-2.5Sn alloy were subjected to LH2 exposure and tensile test at 20K (-253°C) and at 77K (-196°C). The tensile properties obtained from different specimens were compared and analyzed. Also the notch to smooth tensile strength ratio (NSR) were compared and analysed. The obtained NSR was above unity which confirms the low notch brittleness. The tensile strength values between LH2 exposed and unexposed specimen at 20K and 77K were compared and it revealed greater compatibility of Ti-5Al-2.5Sn-ELI with liquid hydrogen environment.

Fracture mechanical studies have become a vital aspect of the design of concrete structures. This work aims to analyse/validate the size-effect of structural components in light of principles of Linear Elastic Fracture Mechanics (LEFM). Various models of a quasi-brittle material with different geometries have been analysed for Stress Intensity Factors (SIF) using Abaqus/CAE: a finite element analysis software. The effect of crack-to-depth ratio, span-to-depth ratio and specimen size on SIF values have been studied. Also the variation in SIF values with respect to changing the position of concentrated load application and initial notch on the specimen have been studied. It is found that for a particular notch-to-depth ratio, the SIF increases with a decrease in specimen size. Also, at a constant span-to-depth ratio, SIF increases with increase in the notch-to-depth ratio.

Mostly, magnetorheological damper research is going on flow mode and shear mode type of damper. Less work is carried out by researcher on squeeze mode type of damper. This will give higher force as compare to flow mode and shear mode type of MRF damper at low excitation. So, this kind of damper can be used as vibration isolation for high impact loading at low amplitude application like engine mount. Aim of this paper is optimized design of Squeeze mode damper for low amplitude application by using design of experiment tool. For design of squeeze mode type of MR damper magnetic field distribution is very important study to improve damping performance. Various parameters like length of coil, diameter of squeeze plate, current passing through coil, number of turns, area of coil and MR fluid gap are considered during optimization and optimization is done by using FEMM software It shows that length of coil, Number of turn and area of coil increases damping performance improves. Other design parameters are check out with mathematical model of MR damper with theoretical calculation like…

Calcium methoxide obtained from quick lime is used as a solid catalyst in the transesterification reaction between palm stearin with methanol using tetrahydrofuran (THF) as co-solvent for biodiesel production. In this work, quick lime was used to prepare calcium oxide by heat treatment at the different temperatures, after that calcium oxide was further reacted with methanol to produce calcium methoxide catalyst. The properties of Calcium methoxide (Ca(OCH3)2) was characterized by XRD, SEM, BET, TGA, EDX and FTIR. The optimum conditions of biodiesel production were studied through response surface methodology and central composite design. The conversion of fatty acid methyl ester (FAME) was determined by proton nuclear magnetic resonance spectroscopy (1H-NMR). The results depicted that calcined quick lime at 800 °C for 3 h contained high calcium oxide content. The Ca(OCH3)2 catalyst prepared at 65 °C for 3 h gave high surface area and catalytic activity. The optimum conditions for biodiesel production were 2.33% w/w of catalyst, 1 : 9.39 of palm stearin to methanol molar ratio, 102…

We investigated the use of durian shell-derived activated carbon (DSAC) for the removal of Cu2+. To determine the optimal condition for Cu2+ removal, the response surface methodology (RSM) was used to establish a second-order polynomial model with variables such as Cu2+ concentration (Ci), adsorbent dosage (dDSAC) and pH. With R2 = 0.9847 and P-value < 0.0001, the model was proved to be statistically significant. The RSM based confirmation test revealed that the removal of Cu2+ was maximum (99.6%) at optimal conditions: Ci = 61.6 mg/L, dDSAC = 5.0 g/L and pH = 5.2. Based on calculated R2, data fitness for adsorption isotherms were positioned as follows: Langmuir > Tempkin > Freundlich. In other words, monolayer adsorption was the most favorable behavior with maximum capacity of 76.92 mg/g from Langmuir model. Interestingly, DSAC was reused at least five times without a considerable decrease of Cu2+ removal efficiency. Therefore, durian shell can be used as a highly effective, reusable and promising raw material to fabricate the activated carbon.

The purpose of this study is to evaluate the Thermal comfort of the Thai elderly in air-conditioned space. The quantitative evaluation was conducted using 163 senior participants while recording their expressed satisfaction within the thermal environment in four public health service buildings in Phitsanulok Province, Thailand. It revealed that for the Thai elderly, the Predicted Mean Vote could not be used to identify the Thermal Sensation Vote. In addition, the results of this study indicated that personal factors, such as gender, age, and underlying disease correlating affect their Thermal Sensation Vote. Perhaps most significantly, a coincidental finding was that the thermal sensation of the Thai elderly was strongly dependent upon the condition of the occupant’s metabolic syndrome, which belonged to the Non-Communicable Disease group. This study assumed that in the elderly, the metabolic syndrome might have an effect on their metabolic rate (as one of the six factors of thermal comfort). In terms of the environmental factors, the on-site environmental data was collected via…

This study evaluates the thermal influence of sunspaces from a representative case, The Historical and Anthropological Museum Maurice Van de Maele, Valdivia, Chile. For this case, different possible situations were analysed, including sunspaces, through energy simulations. The simulations were compared to the current state of the buildings, to perform an analysis of the possible energetic saving by incorporating sunspaces into construction. The specific climate of the area defined that during the majority of the year heating is needed, more than cooling, for the buildings. The results show that there are cases where, using sunspaces as an intermediary between interiors and exteriors, significant savings of over 60% in winter can be obtained.

A benchmark test will insure that the equipment, procedures, and uncertainty estimates are adequate. The experiments of a well-known bulk carrier bare hull shape (the model LHI-007) has been set up and conducted at towing tank Indonesian Hydrodynamic Labotatory. The aim of the present study is to contribute data of the surface ship resistance model-scale database in calm water on one hand, and on the other – reliable Experimental Fluid Dynamics (EFD) data, as part of an internal benchmark test. Conclusions are made with regard to the available data and past uses and recommendations are provided for future uses of the available data and future data procurement.

This paper aims to report the influence of water vapor on thermal oxide scale grown on incoloy800HT at 850°C. Alloy was prepared in coupons with a surface finishing up to 1200 SiC abrasive paper. Oxidization was performed in tubular furnace at 850°C during 50 hours. The oxidizing gases were varied as a dry oxygen gas and a wet oxygen gas. Thermal oxide morphology was characterized by scanning electron microscopy (SEM). Oxide phases were identified by X-ray diffraction (XRD) and Raman spectroscopy techniques. The oxide multilayers were revealed in all the oxidized samples. Oxide spallation was obviously detected on the samples oxidized under a dry oxygen gas, whereas, the spallation was not detected on the samples oxidized under a wet oxygen gas. Moreover, by water vapor mixing gas, the alloy surface presented a finer oxide. XRD and Raman spectroscopy provided the coincident oxide identification results. The corundum oxide of (Fe,Cr)2O3and the spinel oxide of (Fe,Cr)3O4were identified as a typical thermal oxide, however, the oxides were different in stoichiometry. The existence of…

Nano-filler reinforced epoxy composites has been investigated in this study subjected to various mechanical and pin-on-disk tribological tests. Two different types of nano-filler were used namely, rigid nano-silica (SiO2) particles and soft nano-rubber particles. Incorporation of nano-filler in polymer matrix enhance mechanical properties. In addition, tribological response of composites are also better compared to neat epoxy polymer. However, the effect of nano-silica addition is much more pronounced than that of nano-rubber due to the high rigidity of nano-silica reinforced epoxy composite. This was mainly attributed to transfer film layer (TFL) formation. The TFL was further investigated by electron microscope and nanoindentor. The best set of tribological properties was achieved at 8 wt. % nano-silica addition. This was due to better reinforcement dispersion and continuous transfer film layer formation which eventually control the overall friction and wear mechanism.

TiB2 particulate reinforced titanium matrix composites were prepared by mechanical alloying and spark plasma sintering. Volume fraction of TiB2 powders in the composites are 5%, 10%, 15%. The effect of milling time and the volume fraction of reinforcement on microstructure and properties of the composites were studied. The results show that with increasing milling time, the size of powder particles decreases, quantity of them increases, and microstructure of the sintered samples becomes finer and more uniform. When milling time reaches 30h, the trend of powder agglomeration increases, the downward trend of the particle size becomes slowly. With the milling time, the density of titanium matrix composites is on the rise. The density of 10vol%TiB2 particulate reinforced titanium matrix composites can reach 4.799 g/cm3, with 30h milling time and sintering at 900°C. The density and hardness of the composites increase with increasing the volume fraction of TiB2. When the volume fraction of TiB2 is 15%, after milling 10h and sintered at 800°C, the density and hardness of the composites can…

This study presents results of an experimental investigation conducted to investigate the mechanical properties of sisal and glass fiber reinforced concrete. Four basic concrete mixes were considered: 1) Plain concrete (PC) containing ordinary natural aggregates without any fibers, 2) sisal fiber reinforced concrete (SFRC), 3) sisal and glass fiber reinforced concrete (SGFRC), 4, glass fiber reinforced concrete (GFRC). Investigated properties were compressive strength, splitting tensile strength, flexural tensile strength and workability. The results of fiber reinforced concrete mixes were compared with plain concrete to investigate the effect of fibers on the mechanical properties of fiber reinforced concrete. It was determined that addition of different kinds of fibers (natural and synthetic) is very useful to produce concrete. The addition of fibers was resulted into higher compressive strength, splitting and tensile strength. However, the workability of the fiber reinforced concrete was found lower than the plain concrete due to the addition of fibers in the concrete.

The dependences of the concentration profile and the particle size distribution of asbestos-cement dust on the dimensions of working room along the horizontal and vertical axes were obtained in the work. The paper considers the dependence of the median size values of dust particles on the methods of air exchange organization in the working room.

Buckling of slender bars subject to axial compressive loads represents a critical design constraint for light-weight truss structures. Active buckling control by actuators provides a possibility to increase the maximum bearable axial load of individual bars and, thus, to stabilize the truss structure.For reasons of cost, it is in general not economically viable to use such actuators in each bar of the truss structure. Hence, it is an important practical question where to place these active bars. Optimized structures, especially when coupled with active elements to further decrease the number of necessary bars, however, lead to designs, which, while cost-efficient, are especially prone to bardamages, caused, e.g., by material failures. Therefore, this paper presents a mathematical optimization approach to optimally place active bars for buckling control in a way that secures both buckling and general stability constraints even after failure of any combination of a certain number of bars. This allows us to increase the resilience of the system and guarantee stable behavior even in…

Mathematical models of a suspension strut such as an aircraft landing gear are utilized by engineers in order to predict its dynamic response under different boundary conditions. The prediction of the dynamic response, for example the external loads, the stress and the strength as well as the maximum compression in the spring-damper component aids engineers in early decision making to ensure its structural reliability under various operational conditions. However, the prediction of the dynamic response is influenced by model uncertainty. As far as the model uncertainty is concerned, the prediction of the dynamic behavior via different mathematical models depends upon various factors such as the model's complexity in terms of the degrees of freedom, material and geometrical assumptions, their boundary conditions and the governing functional relations between the model input and output parameters. The latter can be linear or nonlinear, axiomatic or empiric, time variant or time-invariant. Hence, the uncertainty that arises in the prediction of the dynamic response of the resulting…

Yogyakarta earthquake, Mw 6.3, 27 May 2006 had killed 5,571 victims and destroyed more than 1 million buildings. This incident became the most destructive earthquake disaster over the last 11 years in Indonesia. Earthquake mitigation plan in the area has been carried out by understands the location of the fault. The location of the fault is still unclear among geoscientists until now. In this case, analysis of the aftershocks using oct-tree importance sampling method was applied to support the location of the fault that responsible for the 2006 Yogyakarta earthquake. Oct-tree importance sampling is a method that is recursively subdividing the solution domain into exactly eight children for estimating properties of a particular distribution. The final result of the subdividing process is a cell that has a maximum Probability Density Function (PDF) and identified as the location of the hypocenter. Input data consists of the arrival time of the P wave and S wave of the aftershocks catalog from 3-7 June 2006 and the coordinate of the 12 seismometers, and 1D velocity model of the study…

The full height rectangular opening castellated steel beam failed in Vierendeel mechanism. This makes the flexural capacity of castellated steel beam is lower than the original IWF section. This paper discusses analysis and test result of a full height rectangular opening castellated steel beam with diagonal stiffener. The diagonal stiffener used in this research has a purpose of preventing Vierendeel mechanism. This research used two specimens, a short span specimen to study shear behavior, and a long span specimen to study flexural behavior. Test results show that the long span specimen can avoid Vierendeel mechanism and increase the yield moment capacity by 1.6 times of the original IWF section. The failure of the short span specimen is a combination of shear failure and Vierendeel mechanism as in elastic condition, the diagonal stiffener, flange, and web post were worked and failed together. Based on the test result, truss analysis method can be used to calculate the flexural capacity of full height rectangular opening castellated steel beam with diagonal stiffener. Theoretical…