Papers by Keyword: Von Mises Stress

Abstract: The longitudinal turning of 304 austenitic stainless steel (ASTSTS) occurred on a lathe using a Tungaloy-made carbide insert (SNMG 12 04 08). The machining parameters were the cutting velocity, feed rate, and depth of cut (DOC). The machining occurs according to the L27 Taguchi design. The strain hardening index (n) and strength coefficient (K) were available by tensile test on the specimen. The chip reduction coefficients (CRC) and von Mises stresses (VMS) were experimentally available. The maximum CRC and the maximum von Mises stresses were for moderate speed, moderate feed, and moderate depth of cut. The SEM observation on chip surfaces at different experimental conditions revealed hardening behaviour for most of the experimental conditions. However, under the specific condition, extensive ductile behaviour was significant, which resulted in maximum von Mises stress generation. The application of design of experiment (DOE) methodology yielded the theoretical model. The trend of CRC found through the theoretical model showed a similarity with the curve-fitting trend from experimental data. However, a fuzzy inference system (FIS) model showed better adequacy in comparison to the other models in the present study.

Abstract: This paper analyzes stress distribution in a solid elliptical cross-section under axial load, bending moment, and torsional load, which are common in structural and mechanical engineering. The study aims to derive an explicit formula for von Mises stress as a function of cross-sectional coordinates, providing a unified measure to assess material failure under combined loads.

Abstract: The dry turning was done on the high tensile low alloy steel. The Indoloy carbide tool was used. The input parameters were speed, feed, and depth of cut (DOC, d). The chip reduction coefficient (CRC) and von Mises stress (VMS) were the output responses. Universal tensile testing was done to find out the strength coefficient (K) and strain hardening exponent (n). "K" and "n" were incorporated to obtain the von Mises stress (VMS). The experiments were performed following the L₉ array (Taguchi). The analysis of variance (ANOVA) was done for the CRC, with the lower the better condition. The ANOVA was done for VMS with the lower-better condition. The ANOVA was done by developing a MATLAB program. The feed contributed strongly to both the CRC (80.1381% contribution) and VMS (33.1490% contribution) minimizations. A Taguchi-Fuzzy inference system (FIS) simulation was done (MATLAB software) to select optimal parameters. CRC and VMS were the inputs, and MPCI (multi performance characteristic index) was the output for the simulation. The simulation was done based on the rules. The optimal parameters were found at moderate speed, high feed, and moderate DOC. Machining chips were collected for different experimental conditions. The chip form study was done. The chip surfaces were examined in the scanning electron microscope (SEM). The simulation result was validated by chip form study and SEM observation of chip.

Abstract: Additive manufacturing (AM) technologies have been evolved over the last decade, enabling engineers and researchers to improve functionalities of parts by introducing a growing technology known as multi-material AM. In this context, fused deposition modeling (FDM) process has been modified to create multi-material 3D printed objects with higher functionality. The new technology enables it to combine several types of polymers with hard and soft constituents to make a 3D printed part with improved mechanical properties and functionalities. Knowing this capability, this paper aims to present a parametric optimization method using a genetic algorithm (GA) to find the optimum composition of hard polymer as polylactic acid (PLA) and soft polymer as thermoplastic polyurethane (TPU 95A) used in Ultimaker 3D printer for making a rectangular sample under flexural load in order to minimize the von Mises stress as an objective function. These samples are initially presented in four deferent forms in terms of composition of hard and soft polymers and then, after the optimization process, the final ratio of each type of material will be achieved. Based on the volume fraction of soft polymers in each sample, the equivalent topologically-optimized samples will be obtained that are solely made of single-material PLA as hard polymer under the same flexural load as applied to multi-material samples. Finally, the structural results and manufacturability in terms of the generated support structures, as key element of some AM processes, will be compared for the resultant samples created by two methods of optimization.

Abstract: The purpose of this paper focuses on adhesive layer strength while having a thermal cycling of honeycomb composite sandwich structure by using the uniform design of experiments method improving the von Mises stress of honeycomb structure. Three system parameters of the honeycomb structure are selected as the control factors to be improved. Uniform design of experiment is applied to create a set of simulation experiments. Applying ANSYS/Workbench software, the finite element modelling is investigated and the von Mises stress of the honeycomb structure is calculated under metal-honeycomb core flatwise tensile test. From the numerical results, the best honeycomb structure dimension of all the experiments which causes the smaller von Mises stress is selected as the improved version of design. Finally, the best model of the experiments which causes the minimum equivalent stress is regarded as the improved version of design. Compared with the original design, the result of ASTM C297 improved version is 17.386 MPa, which mean improved 36.28%, ASTM C364 improved version is 19.015 MPa, which mean improved 25.26%, ASTM C365 improved version is 16.86 MPa, which mean improved 12.35%.

Abstract: Generally, implants fixations in orthopedic surgery are insured by bone cement; which is generated mainly from polymer polymethylmethacrylate (PMMA). Since, the cement is identified as the weakest part among bone-cement-prosthesis assembly. Hence, the characterization of mechanical behaviour is of a crucial requirement for orthopaedic surgeon’s success. In this study, we investigates the failure behaviour of bone cement, under combined shear and compression loading, for the aim to determine the strengths of bone cement for different mode loading conditions. Therefore, experimental cylindrical specimens has been tested to assess different shear-compression stresses. Based on the mechanical tests, a finite elements model of cylindrical specimens was developed to evaluate stresses distribution in the bone cement under compression, shear and combined shear-compression loading. Results show that, the load which leading to the failure of the cement decreased with increasing of the specimen angle inclination with respect of loading direction.

Abstract: The aim of the present study is to investigate the comparison between the biomechanical behavior of the dental prosthesis composed of three implants replacing successively the premolar and two molars and the dental bridge located between two implants. Both dental structures were subjected to the same masticatory loading (Corono-apical, Linguo-buccal and Disto- mesial). Three-dimensional finite element models of dental structures were developed to determine the stress distribution under simulated applied loads. In this study the biomechanical behavior of prosthetics dental crowns subjected to static loads in contact with the jawbone has been highlighted. Biomechanical simulations indicated that the equivalent stresses in the dental bridge are greater than that produced in the dental prosthesis. The dental bridge can be assimilated to a beam at the embedded ends, subjected to the bending.

Abstract: This research focuses on the diaphragm design of the graphene MEMS capacitive microphone. Simulation part will be first involved in order to get the optimum dimensions of each elements by COMSOL multiphysics simulation software. This study will discussed on mechanical behavior of graphene diaphragm for MEMS capacitive microphone. First stage will implicated a theoretical model of diaphragm MEMS capacitive microphone. Then, boundary element based simulation with some mathematical formula will be used to design and evaluate the model. The output value of selective parameters such as the thickness and diameter of diaphragm, air gap and others are crucial in order to further fabricate the MEMS capacitive microphone. The proposed design of graphene diaphragm are in circular shape and square shape. The mechanical sensitivity of diaphragm with the pressure changes will be the crucial parameters in early stage. The results revealed that the circular shape diaphragm shows the better deflection with the thicker diaphragm gives the lower deflection. Von mises stress for both diaphragm shape also recorded in order to avoid the failure of the proposed design.

Abstract: Silicon and Silicon Nitride are vigorously utilized and explored in micro and nano fabrication technology as they have excellent mechanical and electrical characteristics suitable for NEMS device application. In this study, both of them are analyzed using COMSOL Multiphysics software to evaluate the strength capability of the material when used as filtration membrane in artificial kidney. The artificial filtration membrane is a crucial part in an artificial kidney system as it functions to filter out all wastes from blood stream. This paper investigates the effect of membrane thickness experiencing applied pressure of 1332.3 Pa and 7332.7 Pa on membrane deflection and von Mises stress at the center of the filtration membrane. Those mechanical characteristics at different pore geometry and structure are evaluated against applied pressure on the filtration membrane surface. The results show that the pore geometry and shape for a membrane with thickness of higher than 200 nm will not have significant influences on the deflection and stress characteristics. Therefore, thicker membrane will result to a more stable filtration process that would be able to withstand simulated blood stream pressure in an artificial kidney.

Abstract: Pipes in power plants generally subjected to high pressures and temperatures. These are connected by elbow, T-joints to get the continuity between different stages. Due to excessive joints the outlet velocity and pressure will drops by considerable amount. Stresses will be produced due to high pressure and temperature of fluid flow, which in turn creates the failure of the pipes. The turbulence of the fluid passing through the pipes will also plays a vital role to decide the outlet pressure and velocity. In this present study pipes are connected by the elbow joint are considered and observed the effect of pipe thickness, turbulence intensity and length of elbow on outlet pressure, velocity, von mises stress and turbulence kinetic energy. It results that with increase in pipe thickness and length of elbow, the velocity, von mises stress and turbulence kinetic energy are decreases but with increase in turbulence intensity, the velocity and turbulence kinetic energy are increases.