scholarly journals A study on damage to mechanical seat cushion made from different materials of extension frame

2018 ◽  
Vol 7 (3.3) ◽  
pp. 315
Author(s):  
Jae Won Kim ◽  
Jae Ung Cho ◽  
Chan Ki Cho ◽  
Jin Oh Kim
Keyword(s):  
Shear Stress ◽  
Statistical Analysis ◽  
Material Property ◽  
Equivalent Stress ◽  
Damage Prediction ◽  
Seat Cushion ◽  
Seat Cushions

Background/Objectives: : Automotive seat is a very important component to prevent accidents by reducing passenger’s tiredness, thus, this study worked on analyzing damage with different materials of extension frames of mechanical seat cushions.Methods/Statistical analysis: In this study, we performed an experiment on cushion extension frames by splitting it into two parts. We studied about the damage prediction of slave body for each material property of ABS, PP, PLA, and PA6.6. For analyzing the condition, we assigned the side part of the master body for fixed support, and we progressed on analysis by applying with 690N on the entire part of the slave body.Findings: This research worked on the study of damage to different materials of extension frames of seat cushions. After confirming the stress equivalence of the entire model for each material, PP showed the highest equivalent stress of 180.88MPa, and ABS showed the lowest equivalent stress of 151.73MPa. Overall, we could see that in the order of ABS, PA6.6, PLA, PP have a higher tendency to be broken. In addition, when confirming equivalent stress of master body depending on materials of slave body, PA6.6 showed the highest equivalent stress of 166.3MPa, and ABS showed the lowest equivalent stress of 124.06MPa. Overall, we could see that in the order of ABS, PP, PLA and PP6.6 have a higher tendency to be broken. In comparing shear stress on the gear part, which has the highest tendency to be broken in among the entire model, depending on the material of the slave body, PLA showed the greatest shear stress of 88.945MPa, and ABS showed the lowest shear stress of 69.766MPa.Improvements/Applications: This study worked for the improvements and applications of cushion extension frames as the securement of material by investigating these factors.  

Influence of turbulent shear stresses on the numerical blood damage prediction in a ventricular assist device

2019 ◽  
Vol 42 (12) ◽  
pp. 735-747 ◽  
Author(s):  
Benjamin Torner ◽  
Lucas Konnigk ◽  
Frank-Hendrik Wurm
Keyword(s):  
Shear Stress ◽  
Equivalent Stress ◽  
Volumetric Analysis ◽  
Turbulent Shear ◽  
Shear Stresses ◽  
Ventricular Assist ◽  
Damage Prediction ◽  
Blood Damage ◽  
Damage Models ◽  
Order Of Magnitude

The blood damage prediction in rotary blood pumps is an important procedure to evaluate the hemocompatibility of such systems. Blood damage is caused by shear stresses to the blood cells and their exposure times. The total impact of an equivalent shear stress can only be taken into account when turbulent stresses are included in the blood damage prediction. The aim of this article was to analyze the influence of the turbulent stresses on the damage prediction in a rotary blood pump’s flow. Therefore, the flow in a research blood pump was computed using large eddy simulations. A highly turbulence-resolving setup was used in order to directly resolve most of the computed stresses. The simulations were performed at the design point and an operation point with lower flow rate. Blood damage was predicted using three damage models (volumetric analysis of exceeded stress thresholds, hemolysis transport equation, and hemolysis approximation via volume integral) and two shear stress definitions (with and without turbulent stresses). For both simulations, turbulent stresses are the dominant stresses away from the walls. Here, they act in a range between 9 and 50 Pa. Nonetheless, the mean stresses in the proximity of the walls reach levels, which are one order of magnitude higher. Due to this, the turbulent stresses have a small impact on the results of the hemolysis prediction. Yet, turbulent stresses should be included in the damage prediction, since they belong to the total equivalent stress definition and could impact the damage on proteins or platelets.

scholarly journals Simulation of human bone implant duralium material with variation loading using Ansys software

2018 ◽  
Vol 204 ◽  
pp. 07020
Author(s):  
Didin Mujahidin ◽  
Poppy Puspitasari ◽  
Djoko Kustono
Keyword(s):  
Stainless Steel ◽  
Shear Stress ◽  
Equivalent Stress ◽  
Titanium Implants ◽  
Material Strength ◽  
Body Parts ◽  
Ansys Software ◽  
Implant Materials ◽  
Broken Bones ◽  
Material Hardness

Bone implants are a tool used as a support of body parts, and bone support in cases of fractures. Scaffold, plate, bone screw, and some other tools can be used in combination to support and fill the connection between broken bones before the tissue grows. The most commonly used implant materials are Titanium, Stainless steel and ceramics, which are very common in the use of medical devices. Biocompatible materials are taken into consideration when planning a medical device. This research intended to know the durability of duralumin material as the latest implant material, as the development and breakthrough in health world. The research methodology used in this study was the optimization in Ansys software 18.1. The implants were designed, the material strength was determined and then given imposition with 6 variations (450 N, 550 N, 650 N, 750 N, 850 N and 950 N). The optimization was a method that identified mat erial strength including Equivalent Stress, Shear Stress and Total Deformation of duralumin material as implant materials with loading variations. Based on the results of the research, the duralumin material had a equivalent stress of 475,700 Pa which was higher than 950000 Pa for ZnO-Al2O3 implants, while the duralumin shear stress of 1084500 Pa was higher than 313720 Pa for ZnO-Al2O3 implants. When compared with titanium implants, the highest equivalent stress of 150000 Pa duralumin material had a higher compression stress than titanium. The highest shear stress of titanium 4358.1 Pa means an implant with a higher shear duralumin material of titanium. Whereas if it was compared to stainless steel with voltage press 564000000 Pa, then the duralumin’s pressure was getting lower. Material hardness affects resistance to wear and tear. Duralumin material hardness was lower than Titanium and ZnO-Al2O3, so total Duralumin deformation (elasticity) was higher than Titanium and ZnO-Al2O3.

scholarly journals The generalized criterion of multiaxial random fatigue based on conception proposed by prof. Macha

2019 ◽  
Vol 300 ◽  
pp. 15001
Author(s):  
Tadeusz Łagoda ◽  
Marta Kurek ◽  
Karolina Łagoda
Keyword(s):  
Shear Stress ◽  
Complex Number ◽  
Mathematical Problem ◽  
Equivalent Stress ◽  
Complex Stress ◽  
Complex Numbers ◽  
Pure Bending ◽  
Pure Torsion ◽  
Special Cases ◽  
Random Fatigue

This criterion has been repeatedly verified, analyzed and special cases of this criterion reducing complex stress to equivalent uniaxial were taken into account. Since both normal and shear stress are vectors, we encounter the mathematical problem of adding these vectors, and the question arises how to understand the obtained equivalent stress, because two perpendicular vectors are added with weighting factors. Therefore, in this work it was proposed to adopt a system of complex numbers. Normal stress was defined as the real part and shear stress as imaginary part. As a result, on the basis of the defined complex number and basing on pure bending and pure torsion after transformations, the expression for equivalent stress was identical to the previously proposed criteria defined on the basis of the concept of prof. Macha.

Ship Performance Research Based on BP Neural Network

2014 ◽  
Vol 709 ◽  
pp. 176-179
Author(s):  
Han Liu ◽  
Fang Zhen Song ◽  
Ming Ming Li ◽  
Bo Song
Keyword(s):  
Neural Network ◽  
Shear Stress ◽  
Bp Neural Network ◽  
Optimization Design ◽  
Maximum Shear Stress ◽  
Equivalent Stress ◽  
Orthogonal Experimental Design ◽  
The Neural Network ◽  
Maximum Equivalent Stress ◽  
Ship Performance

The problem is solved that it is hard to provide analysis formulas about the maximum equivalent stress, the maximum shear stress and the structural geometric parameters for a ship. The finite element calculation is done with orthogonal experimental design under the most dangerous case. The data obtained are used as the training and test samples to establish BP neural network models of ship’s maximum equivalent stress and maximum shear stress. With the aid of Neural network toolbox in MATLAB, the topological structure of BP neural network mapping relationship between the whole ship performance indexes and design variables is established. The training and testing are completed with the data tested by the shipyard and the correctness of this network is verified. The neural network required for further optimization design is obtained. The neural network is helpful in reducing the ship mass without exceeding the allowable stress.

Grid-Induced Numerical Errors for Shear Stresses and Essential Flow Variables in a Ventricular Assist Device: Crucial for Blood Damage Prediction?

2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Lucas Konnigk ◽  
Benjamin Torner ◽  
Sebastian Hallier ◽  
Matthias Witte ◽  
Frank-Hendrik Wurm
Keyword(s):  
Shear Stress ◽  
Prediction Models ◽  
Stokes Equations ◽  
Grid Size ◽  
Blood Pump ◽  
Navier Stokes ◽  
Shear Stresses ◽  
Damage Prediction ◽  
Blood Damage ◽  
Stress Calculation

Adverse events due to flow-induced blood damage remain a serious problem for blood pumps as cardiac support systems. The numerical prediction of blood damage via computational fluid dynamics (CFD) is a helpful tool for the design and optimization of reliable pumps. Blood damage prediction models primarily are based on the acting shear stresses, which are calculated by solving the Navier–Stokes equations on computational grids. The purpose of this paper is to analyze the influence of the spatial discretization and the associated discretization error on the shear stress calculation in a blood pump in comparison to other important flow quantities like the pressure head of the pump. Therefore, CFD analysis using seven unsteady Reynolds-averaged Navier–Stokes (URANS) simulations was performed. Two simple stress calculation indicators were applied to estimate the influence of the discretization on the results using an approach to calculate numerical uncertainties, which indicates discretization errors. For the finest grid with 19 × 106 elements, numerical uncertainties up to 20% for shear stresses were determined, while the pressure heads show smaller uncertainties with a maximum of 4.8%. No grid-independent solution for velocity gradient-dependent variables could be obtained on a grid size that is comparable to mesh sizes in state-of-the-art blood pump studies. It can be concluded that the grid size has a major influence on the shear stress calculation, and therefore, the potential blood damage prediction, and that the quantification of this error should always be taken into account.

scholarly journals Power Spinning of the Curved Head with Tailor Welded Aluminum Alloy Blank: Deformation, Microstructure, and Property

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1359
Author(s):  
Fei Ma ◽  
Pengfei Gao ◽  
Pengyu Ma ◽  
Mei Zhan
Keyword(s):  
Aluminum Alloy ◽  
Material Property ◽  
Equivalent Stress ◽  
Weld Zone ◽  
Weld Line ◽  
Base Material ◽  
Equivalent Strain ◽  
Inhomogeneous Material ◽  
Loading Path ◽  
Power Spinning

The power spinning of tailor-welded blank (TWB) provides a feasible way to form the large-scale curved heads of aluminum alloy. However, the inhomogeneous material property of TWB produces different and more complex spinning behaviors compared with the traditional spinning of an integral homogenous blank. In this research, the deformation characteristics, microstructure, and the properties of the power spun curved head with aluminum alloy TWB were studied. A finite element model considering the inhomogeneous material property of welded blank is developed for the analysis of the power spinning process. To conduct accurate and efficient simulation, an effective meshing method is proposed according to the feature of TWB. The simulation and experimental results show that the weld zone (WZ) presents the larger equivalent stress but smaller equivalent strain than base material zone (BMZ) in power spinning due to its larger deformation resistance. Under the combined effects of the spiral local loading path and inhomogeneous deformability of TWB, the equivalent strain near the weld zone has an asymmetric V-shaped distribution. Strain inhomogeneity gradually increases with deformation and leads to an increase of the flange swing degree. In addition, the circumferential thickness distribution is relatively uniform, which is little affected by the existence of the weld line. However, the circumferential unfitability distribution becomes non-uniform and the roundness is worsened due to the existence of the weld line. Compared to the initial blank, the microstructure in WZ and BMZ are both elongated after spinning. The tensile strength is improved but plasticity reduced after power spinning based on the circumferential and radial tests of WZ and BMZ. The results are of theoretical and technical guidance for the power spinning of the curved head component with TWB.

The Loading Ability Analysis of Spiral Spline

2013 ◽  
Vol 475-476 ◽  
pp. 1507-1512
Author(s):  
Jun Yang ◽  
Hua Li ◽  
Qing Tao Li ◽  
Jin Yao
Keyword(s):  
Shear Stress ◽  
Equivalent Stress ◽  
Force Analysis ◽  
Calculation Methods ◽  
Flexural Stress ◽  
Relationship Of ◽  
The Relationship

With the detailed force analysis of spiral spline transmission, the relationship of each force was derived. On the basis of this, referred to the designing and checking criterion of the straight-tooth spline transmission and spiral transmission, the calculation methods of the surface extrusion stress (or pressure) of the spiral spline teeth side, the shear stress and the max-flexural stress of the spiral spline teeth root, and the equivalent stress of the screw bolt were derived, and the checking criterions for them were put forward. An example, the surface extrusion stress through the calculation methods compared with that through ANSYSWorkbench simulation, verifies the calculation methods of the surface extrusion stress (or pressure) of the spiral spline teeth side.

scholarly journals Numerical Study on Vibration Response and Fatigue Damage of Axial Compressor Blade Considering Aerodynamic Excitation

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1835
Author(s):  
Xi Fu ◽  
Chao Ma ◽  
Jiewei Lin ◽  
Junhong Zhang
Keyword(s):  
Shear Stress ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Equivalent Stress ◽  
Axial Compressor ◽  
Compressor Blade ◽  
Torsional Shear ◽  
Fatigue Damage Accumulation ◽  
Fatigue Model

Axial compressor blades with a deformed initial torsion angle caused by aerodynamic excitation resonated at the working speed and changed the rule of fatigue damage accumulation. The fatigue life of a blade has a prediction error, even causing serious flight accidents if the effect of torque causing damage deterioration of the blade fatigue life is neglected. Therefore, in this paper, a uniaxial non-linear fatigue damage model was modified using the equivalent stress with torsional shear stress, and the proposed fatigue model including the torsional moment was used to study the compressor blade fatigue life. Then, the blade numerical simulation model was established to calculate the vibration characteristics under complex loads of airflow excitation and a rotating centrifugal force. Finally, the blade fatigue life under actual working conditions was predicted using the modified fatigue model. The results show that the interaction between centrifugal and aerodynamic loads affects the natural frequency, as the frequencies in modes dominated by bending deformation decreased whereas those dominated by torsional deformation increased. Furthermore, the blade root of the suction surface showed stress concentration, but there is an obvious difference of stress distribution and amplitude between the normal stress and the equivalent stress including torsional shear stress. The additional consideration of the torsional shear stress decreased the predicted fatigue life by 4.5%. The damage accumulation rate changes with the loading cycle, and it accelerates fast for the last 25% of the cycle, when the blade fracture may occur at any time. Thus, the aerodynamic excitation increased the safety factor of blade fatigue life prediction.

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