STRESS ANALYSIS USING FINITE ELEMENT METHOD ON SIALON/AISI 430 FERRITIC STAINLESS STEEL JOINT

Ceramic has many good characteristics for high temperature applications such as in heat exchangers. In the actual application of the ceramic to the structures, a ceramic-to-metal joint is unavoidable. This makes joining of ceramic to metal a critically important technology in advanced engineering. However, the fundamental problem in joining of metals and ceramics is the development of residual stresses which originated from the property mismatch between the ceramic and metal. A finite element analysis (FEA) using ANSYS was used to evaluate the residual stresses in the joints. In this analysis, stress analyses were conducted on sialon/AISI 430 joint. The joint was assumed to be perfectly bonded at the interface at 1200°C and stresses developed during cooling down to room temperature. Sequential coupled-field analysis was performed with PLANE55 and PLANE42. Model was simplified to two dimensional (2-D) problems, since its rotation about the axis of symmetry will generate the complete volume of the cylinder. It was found that the maximum tensile stress occur at the edge of sialon, close to the joint interface. The influence of thickness of sialon, diameter and joint design on the generation of stress in sialon was analyzed. Analyses were made to study the effect of each parameter on stress by varying it, for example, thickness of sialon, while fixing the other parameters. It was found that increasing thickness of sialon and diameter of the joint has resulted in increasing magnitude of tensile stress. The stresses can be reduced by employing symmetrical design joint and incorporating interlayer. The verification of the model was carried out by analytical calculation and comparison with literature review. The results of simulated stresses are in good agreement with the analytical method and literature review

Stress Analysis of Steam-Methane Reformer Tube

Reformer tubes are designed to last at least 100,000 hours (11.4 years) of operation, but frequently, some of the tubes in the furnace fail prematurely. Most of the failures occur due to the high temperature and pressure developed within the tubes. Thus, the use of Finite Element Analysis (FEA) software to model, simulate and draw meaningful conclusion from the actual process conditions of the reformer tubes can reveal important information regarding the mechanical and thermal stress response. The main objective of this project is to simulate the combined stress and temperature profiles developed within the reformer tube. This project involves modeling the mechanical and thermal loadings present in the tube as well as simulating the stress distribution across the tube's thickness and length. FEA using ANSYS utilized to analyze stress and temperature profile of the tube. Literature review of reformer tube has been performed and data needed has been identified. Stresses have been computed using ANSYS and verified with theoretical value. It has been seen that the temperature difference across the tube length resulted from the non-unifonn heat transfer coefficient can be considerable causing high thermal stresses. Maximum von mises stress equal to 142.61 MPa developed at the inner surface of the entrance region. The stress then compared with the tensile strength of the tube and it is showed that the tube is able to sustain the stress without fracture

STRESS ANALYSIS USING FINITE ELEMENT METHOD ON SIALON/AISI 430 FERRITIC STAINLESS STEEL JOINT

Ceramic has many good characteristics for high temperature applications such as in heat exchangers. In the actual application of the ceramic to the structures, a ceramic-to-metal joint is unavoidable. This makes joining of ceramic to metal a critically important technology in advanced engineering. However, the fundamental problem in joining of metals and ceramics is the development of residual stresses which originated from the property mismatch between the ceramic and metal. A finite element analysis (FEA) using ANSYS was used to evaluate the residual stresses in the joints. In this analysis, stress analyses were conducted on sialon/AISI 430 joint. The joint was assumed to be perfectly bonded at the interface at 1200°C and stresses developed during cooling down to room temperature. Sequential coupled-field analysis was performed with PLANE55 and PLANE42. Model was simplified to two dimensional (2-D) problems, since its rotation about the axis of symmetry will generate the complete volume of the cylinder. It was found that the maximum tensile stress occur at the edge of sialon, close to the joint interface. The influence of thickness of sialon, diameter and joint design on the generation of stress in sialon was analyzed. Analyses were made to study the effect of each parameter on stress by varying it, for example, thickness of sialon, while fixing the other parameters. It was found that increasing thickness of sialon and diameter of the joint has resulted in increasing magnitude of tensile stress. The stresses can be reduced by employing symmetrical design joint and incorporating interlayer. The verification of the model was carried out by analytical calculation and comparison with literature review. The results of simulated stresses are in good agreement with the analytical method and literature review

Effect of chemical treatment on the tensile properties of single oil palm empty fruit bunch (OPEFB) fibre

A study on effect of chemical treatment on the tensile modulus and strength of single oil palm empty fruit bunch (OPEFB) fibre is presented in this paper. The fibres were treated with alkaline treatment using sodium hydroxide of 5% concentration. Tensile test were conducted in accordance to the ASTM C1557. Results revealed that the tensile modulus of the treated fibres decreases by around 55% as compared to the untreated fibres. Tensile strength on the other hand increases by around 25% with the alkaline treatment. The tensile strength was found to be dependent on the fibre diameter where the strength decreases with the increases in fiber diameter at fracture. SEM revealed higher porosity at larger fibre diameter which contributed to the degradation of the fibre tensile strength. No significant impact by the alkaline treatment was observed to the tensile strain of the fibre

Mechanical and crash performance of unidirectional oil palm empty fruit bunch fibre-reinforced polypropylene composite

The mechanical properties of unidirectional oil palm empty fruit bunch (OPEFB) fibre / polypropylene (PP) composites were analysed. The composites were fabricated with unidirectional fibre orientations of 0°, 45°,and 90°,with mass fractions of 25%, 35%,and 45% for each fibre orientation angle. The composites were then subjected to tensile, flexural,and impact testing. Superior tensile, flexural,and impact strengths were observed for the unidirectional composites with 0° fibre orientation angle. A fibre loading of 35% provided the highest tensile strength,while fibre loadings of 25% and 45% yielded the greatest flexural and impact resistances, respectively.The crash performance of the unidirectional composite subjected to low-velocity impact in the automotive bumper fascia was investigated. The composite exhibited significantly improved energy absorption capability and comparable specific energy absorption when compared with the current material being used for the bumper fascia

Design and performance of a power generating manual treadmill

Treadmills are one of the most popular training equipment in the gym and at home. The working principle of treadmills is by moving the belt with the human knee bending, which creates mechanical energy to turn the belt. A gear or pulley and belt system connects to the generator along the axel line of the rolling bars. The power generated by the DC generator is stored in a battery pack and could be used to charge phones or other equipment. It has been found that treadmills can provide an efficiency of 95% when the DC motor is used and 92% when the AC motor is used. The main objective of this study is to design and fabricate a powder-generating manual treadmill and to analyze the performance of the system under different operation conditions

Experimental analysis of unidirectional oil palm empty fruit bunch fibre-reinforced polymer composites and crash performance using finite element method

The overall objective of this research was to analyze the mechanical properties of unidirectional oil palm empty fruit bunch (OPEFB) fibre reinforced polymer composites and simulating their impact failure response using finite element analysis. The work has primarily focused on the fabrication of unidirectional OPEFB fibre reinforced polymer composites using hand lay-up and compression moulding technique employing Epoxy resin and Polypropylene (PP), respectively. The mechanical properties of the OPEFB fibre/polymer composite have been experimentally characterized by varying the fibre orientation angle by 0°, 45° and 90°. Fibre weight ratio was varied by 25%, 35% and 45% for OPEFB fibre/PP composite. Tensile, flexural and impact strength test conducted in accordance to ASTM D638, ASTM D70 and ASTM D6110, respectively. Superior tensile and flexural strengths were observed for the unidirectional OPEFB fibre/epoxy composite with 0° fibre orientation angle, with increases by of around 30% and 216%, respectively, as compared to pure epoxy. Unidirectional OPEFB fibre/PP composites with fibre loading of 35% and 0° fibre orientation was observed to provide the highest tensile strength. There was an increase of around 130% in the tensile strength as compared to pure PP. The greatest resistance to flexural and impact on the other hand were depicted by the 0° oriented OPEFB fibre/PP composites with fibre loading of 25% and 45%, respectively. The flexural and impact strength were found to be better by 328% and 52%, respectively as compared to pure PP. A finite element modeling was developed for predicting the behavior of the OPEFB fibre/polymer composite using the MAT 54/55 material model that is implemented in the LS-DYNA explicit finite element code. The finite element results were validated against the experimental finding. Good correlations with error lesser by 15% were observed between the simulation and the experimental results. Crash performance of the OPEFB fibre/polymer composite as bumper material has been investigated using finite element analysis. The crash was conducted as frontal impact collision with low velocity impact of 4 km/hr. The specific energy absorption (SEA) of the composites bumper part was found to be comparable with the conventional material used for the bumper. The SEA performance of the unidirectional OPEFB fibre/epoxy composites bumper beam was found to be improved by of around 52% as compared to the conventional Aluminum bumper beam. It was also found that there was an increase by 8.34% in the SEA performance of the unidirectional OPEFB fibre/PP composites bumper fascia as compared to pure PP bumper fascia

Moving magnet linear compressor: Operating characteristics under resonance and off-resonance frequencies

Objectives: This study compared the accuracy of a Linear Equivalent model and a Fourier Transform model in approximating the resonant frequency of a moving magnet oil-free linear compressor. Furthermore, moving magnet linear compressor performance under resonance and off-resonance frequencies was also examined via an experimental approach. Methods: A Linear Equivalent model and a Fourier Transform model were developed and compared with experimental results at low-pressure ratios of 2–2.5. By varying the operating frequency and compressor piston stroke, the power consumption, compressor losses, efficiency, and cooling capacity are assessed experimentally. Results: This study showed that the disparities between resonance frequencies estimated by theoretical models and experimental data were below 10 %. However, the Linear Equivalent model was more accurate than the Fourier Transform model in forecasting the resonance frequency of the linear compressor at a low-pressure ratio of 2–2.5. Both experimental and modelling results showed that the resonance frequency of a linear compressor declined with the increasing compressor stroke but increased with increasing pressure ratio. Experiments were also carried out to compare the performance of linear compressors in resonance and off-resonance frequencies. Results showed that the lowest compressor input power of 91.96 W and the highest motor efficiency of 81.98 % was achieved when the linear compressor was operated at 38 Hz resonance frequency. Moreover, the cooling capacity has been found to increase by 270 W approximately when the linear compressor piston operating stoke extends from 10 mm to 13 mm. Conclusions: In all, this study showed that the linear compressor motor efficiency is the highest when operating at resonance frequency. However, the cooling capacity of the linear compressor system does not vary significantly with operating frequency. A higher cooling capacity can be achieved by increasing compressor piston stroke