FATIGUE ANALYSIS OF NON-LINEAR STRUCTURES WITH VON MISES STRESS

2001 ◽  
Vol 245 (5) ◽  
pp. 947-952 ◽  
Author(s):  
J.Q. SUN ◽  
X. WANG ◽  
L.A. BERGMAN
Keyword(s):  
Fatigue Analysis ◽  
Von Mises Stress ◽  
Linear Structures ◽  
Non Linear ◽  
Von Mises

Percentiles of von Mises Stress from Combined Random Vibration and Static Loading by Approximate Noncentral Chi Square Distribution

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Patrick. A Tibbits
Keyword(s):  
Lower Bounds ◽  
Cumulative Distribution ◽  
Von Mises Stress ◽  
Upper And Lower Bounds ◽  
Linear Structures ◽  
Chi Square ◽  
Mean Values ◽  
Random Loads ◽  
Nonzero Mean ◽  
Von Mises

Firstly, a calculation for percentiles of von Mises stress in linear structures subjected to Gaussian random loads is extended to the case of Gaussian random loads having nonzero mean values, i.e.,the inclusion of static loads. The development is restricted to the case of plane stress. The method includes calculation of a given percentile of von Mises stress to any desired accuracy, a rapid estimate of the percentile, and upper and lower bounds on the von Mises stress. The calculation expands the cumulative distribution function of the von Mises stress as a series of noncentral chi-square distributions. Summation of a sufficient number of terms of the series calculates the percentile to the desired accuracy. The rapid estimate of the percentile interpolates the distribution of the von Mises stress in a small number of inverse noncentral chi-square2 distribution functions. The upper and lower bounds on the percentiles take advantage of the noncentral chi-square distribution of summations of normally distributed stress components. Second and third calculation methods arise from approximations of the distribution of quadratic forms of noncentral normal variables, or equivalently, linear combinations of noncentral chi-square variables. These methods provide rapid estimates of percentiles of von Mises stress in linear structures under random loads having nonzero mean values. The accuracy and computational efficiency of the methods are reviewed and compared. The methods are expected to have wide application in design of and prognostics for components subjected to constant structural loads coupled with random loading arising from vibrations caused by wind, waves, seismic events, engines, turbulence, acoustic noise, etc.

On the Evaluation of the Stress State in Rail Head for Assessing Fatigue Resistance

2014 ◽  
Vol 891-892 ◽  
pp. 1157-1162 ◽  
Author(s):  
Chung Lun Pun ◽  
Qian Hua Kan ◽  
Peter J. Mutton ◽  
Guo Zheng Kang ◽  
Wen Yi Yan
Keyword(s):  
Stress State ◽  
Fatigue Resistance ◽  
Fatigue Analysis ◽  
Multiaxial Fatigue ◽  
Rolling Contact ◽  
Single Parameter ◽  
Von Mises Stress ◽  
Stress Range ◽  
Rail Head ◽  
Von Mises

To search for a single parameter to evaluate the stress state in rail head during wheel/rail rolling contact situations, the stress-based and the strain based phenomenological approaches for multiaxial fatigue analysis can be considered as the candidates. Following the stress-based approach, the maximum von Mises stress range can be applied as a single parameter to evaluate the stress state in the rail head. However, the von Mises stress range only relies on the stress field in the rail head for the fatigue analysis, which is not sufficient for assessing the fatigue resistance of the rail steel. The Smith-Watson-Topper (SWT) method, the strain-based phenomenological approach for multiaxial fatigue analysis which considers stress, elastic strain and plastic strain components, is then adopted to study rolling contact fatigue in the rail head. Combining with the three-dimensional finite element modelling of a steady-state wheel/rail rolling contact, the numerical procedure to calculate the SWT parameter in the rail head is presented. The capability of the SWT method to predict the initiation of fatigue cracks in the rail head is confirmed in a case study. Consequently, the maximum SWT parameter is proposed as a single parameter to effectively evaluate the stress state in the rail head.

scholarly journals Fatigue Analysis pada Pegas Daun Jenis SST 74 dalam Aplikasi Industri Alat Berat dengan Pemodelan Metode Elemen Hingga

ROTASI ◽  
2018 ◽  
Vol 20 (2) ◽  
pp. 118
Author(s):  
Lydia Anggraini ◽  
Yaummil Chairil Agoest Akhir
Keyword(s):  
Life Cycle ◽  
Life Time ◽  
Fatigue Analysis ◽  
Von Mises Stress ◽  
Von Mises

Pada industri manufaktur dan rekayasa alat berat dibutuhkan pemeliharaan yang baik guna menghasilkan produk berkualitas tinggi. Namun, kerusakan secara tidak sengaja dan menyebabkan kerugian besar baik dalam hal moral maupun material bagi perusahaan bisa saja ditemukan. Oleh karena itu, analisis diperlukan untuk meminimalkan kemungkinan kecelakaan. Penelitian ini bertujuan menganalisa kelelahan pada pegas daun untuk aplikasi industri alat berat dengan Metode Elemen Hingga. Pemodelan tersebut dilakukan dengan menghitung beban yang diberikan ke pegas daun, bahan pegas daun dan umur pegas daun yang sebenarnya. Setelah data dikumpulkan, analisis siklus pegas daun dilakukan untuk memberikan beberapa perbaikan. Dengan menggunakan FEA, analisis pertama adalah Von-Mises Stress dan dilanjutkan dengan analisis Life Cycle menggunakan ANSYS, kedua analisis tersebut dapat dihasilkan. Hasil Von-Mises Stress yang dihasilkan di dekat fatigue area adalah 3,923 x 108 Pa dan life cycle antara 91.000 - 93.000 siklus. Di sisi lain, life cycle yang sebenarnya dari pegas daun adalah 108.000 siklus dengan life time adalah 6 bulan. Dengan demikian, hasil FEA adalah perkiraan kondisi nyata pegas daun. Penelitian ini juga memberikan beberapa perbaikan terhadap geometri pegas daun. Perbaikan geometri memberikan hasil dalam mengurangi Von-Mises Stress dan meningkatkan life cycle pegas daun. Von-Mises Stress menurun hingga 3,49 x 108 Pa dan siklus hidup meningkat hingga lebih dari 5 x 105 siklus. Masa pakai juga meningkat hingga 30 bulan.

Low Cycle Fatigue Analysis of after Treatment Device Induced due to Thermal Load by Using Finite Element Analysis

2014 ◽  
Vol 592-594 ◽  
pp. 1104-1108 ◽  
Author(s):  
Swapnil Vitthal Kumbhar ◽  
Vilas Kulkarni ◽  
R.M. Tayade
Keyword(s):  
Crack Initiation ◽  
Thermal Fatigue ◽  
Thermal Loading ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Analysis ◽  
Von Mises Stress ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Von Mises

Cyclic thermal loading causes cyclic thermal stress and thermal fatigue in the component. The goal of this paper is to characterize the thermal fatigue behavior of after-treatment (AT) device, i.e. Exhaust Gas Processor (EGP) and prediction of crack initiation cycles. The paper contains transient thermal analysis to map temperature on EGP model. By taking temperature distribution as input, Elasto-plastic structural analysis is done. Based on stress-strain data and fatigue material property, crack initiation cycles are estimated. For low cycle fatigue analysis, strain based approach, i.e. Brown-Miller Criteria with Morrow mean stress correction factor [1] is used. The von-Mises stress and crack initiation cycles are investigated and S-N curve and Ɛ-N curve are compared with standard graphs.

Development of Web-Based Fatigue Analysis System for Machine Components and Structures

2006 ◽  
Vol 324-325 ◽  
pp. 1265-1268
Author(s):  
Byeong Wook Noh ◽  
Sung In Bae ◽  
Kyung Chun Ham
Keyword(s):  
Fatigue Life ◽  
Equivalent Stress ◽  
Fatigue Analysis ◽  
Von Mises Stress ◽  
Critical Plane ◽  
Web Based ◽  
Critical Plane Approach ◽  
Commercial Program ◽  
Analysis System ◽  
Von Mises

A fatigue analysis program to calculate fatigue lives of mechanical components and structures from FE(Finite Element) results is developed. The useful characteristic of this program is operated under Web environment. So, any designer who design fatigue strength of components and structures can use without other program installation. For the assessment of multi-axial fatigue damage, signed equivalent stress method and critical plane approach have been employed. Each method is compared and the results of Signed von Mises stress method has similar to the results of Smith-Waston-Topper's parameter using critical plane approach. The results were compared with those from commercial program FE-Fatigue6.0 and it was observed that fatigue life and cumulative damage distribution calculated applying same fatigue resistance curve. The results of calculated fatigue life using Web based program agree well with those from FE-Fatigue6.0.

Percentiles of von Mises Stress From Combined Random Vibration and Static Loading by Approximate Noncentral Chi Square Distribution

2011 ◽  
Author(s):  
Patrick A. Tibbits
Keyword(s):  
Lower Bounds ◽  
Cumulative Distribution ◽  
Von Mises Stress ◽  
Upper And Lower Bounds ◽  
Linear Structures ◽  
Chi Square ◽  
Mean Values ◽  
Random Loads ◽  
Nonzero Mean ◽  
Von Mises

Firstly, a calculation for percentiles of von Mises stress in linear structures subjected to Gaussian random loads is extended to the case of Gaussian random loads having nonzero mean values, i.e., the inclusion of static loads. The development is restricted to the case of plane stress. The method includes calculation of a given percentile of von Mises stress to any desired accuracy, a rapid estimate of the percentile, and upper and lower bounds on the von Mises stress. The calculation expands the cumulative distribution function of the von Mises stress as a series of noncentral chi square distributions. Summation of a sufficient number of terms of the series calculates the percentile to the desired accuracy. The rapid estimate of the percentile interpolates the distribution of the von Mises stress in a small number of inverse noncentral chi-square distribution functions. The upper and lower bounds on the percentiles take advantage of the noncentral chi-square distribution of summations of normally distributed stress components. Second and third calculation methods arise from approximations of the distribution of quadratic forms of noncentral normal variables, or equivalently, linear combinations of noncentral chi square variables. These methods provide rapid estimates of percentiles of von Mises stress in linear structures under random loads having nonzero mean values. The accuracy and computational efficiency of the methods are reviewed and compared. The methods are expected to have wide application in design of and prognostics for components subjected to constant structural loads coupled with random loading arising from vibrations caused by wind, waves, seismic events, engines, turbulence, acoustic noise, etc.

Effects of occlusal scheme on All-on-Four abutments, screws and prostheses: A three-dimensional finite element study

2020 ◽  
Author(s):  
Nurullah Türker ◽  
Hümeyra Tercanlı Alkış ◽  
Steven J Sadowsky ◽  
Ulviye Şebnem Büyükkaplan
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Good Prognosis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Group Function ◽  
Occlusal Contact ◽  
Maximum Deformation ◽  
Contact Points ◽  
Von Mises

An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, due to the potential impact of occlusal loads on implant prosthetic components. The aim of the present three-dimensional (3D) finite element analysis (FEA) study was to investigate the stresses on abutments, screws and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. Three-dimensional models of the maxilla, mandible, implants, implant substructures and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO) and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments and prostheses in the All-on-Four concept.

The Influence of Loading Position in A Priori High Stress Detection using Mode Superposition

2020 ◽  
Vol 1 (1) ◽  
pp. 93-102
Author(s):  
Carsten Strzalka ◽  
◽  
Manfred Zehn ◽  
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
A Priori ◽  
High Stress ◽  
Von Mises Stress ◽  
Detailed Knowledge ◽  
Variable Loading ◽  
Numerical Effort ◽  
Von Mises

For the analysis of structural components, the finite element method (FEM) has become the most widely applied tool for numerical stress- and subsequent durability analyses. In industrial application advanced FE-models result in high numbers of degrees of freedom, making dynamic analyses time-consuming and expensive. As detailed finite element models are necessary for accurate stress results, the resulting data and connected numerical effort from dynamic stress analysis can be high. For the reduction of that effort, sophisticated methods have been developed to limit numerical calculations and processing of data to only small fractions of the global model. Therefore, detailed knowledge of the position of a component’s highly stressed areas is of great advantage for any present or subsequent analysis steps. In this paper an efficient method for the a priori detection of highly stressed areas of force-excited components is presented, based on modal stress superposition. As the component’s dynamic response and corresponding stress is always a function of its excitation, special attention is paid to the influence of the loading position. Based on the frequency domain solution of the modally decoupled equations of motion, a coefficient for a priori weighted superposition of modal von Mises stress fields is developed and validated on a simply supported cantilever beam structure with variable loading positions. The proposed approach is then applied to a simplified industrial model of a twist beam rear axle.

scholarly journals Numerical Investigation of the Deformable Porous Media Treated by the Intermittent Microwave

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 757
Author(s):  
Tianyi Su ◽  
Wenqing Zhang ◽  
Zhijun Zhang ◽  
Xiaowei Wang ◽  
Shiwei Zhang
Keyword(s):  
Porous Media ◽  
Heat Transport ◽  
Liquid Water ◽  
Von Mises Stress ◽  
Temperature Deformation ◽  
Local Maxima ◽  
Whole Process ◽  
Surface Areas ◽  
Pulse Ratio ◽  
Von Mises

A 2D axi-symmetric theoretical model of dielectric porous media in intermittent microwave (IMW) thermal process was developed, and the electromagnetic energy, multiphase transport, phase change, large deformation, and glass transition were taken into consideration. From the simulation results, the mass was mainly carried by the liquid water, and the heat was mainly carried by liquid water and solid. The diffusion was the dominant mechanism of the mass transport during the whole process, whereas for the heat transport, the convection dominated the heat transport near the surface areas during the heating stage. The von Mises stress reached local maxima at different locations at different stages, and all were lower than the fracture stress. A material treated by a longer intermittent cycle length with the same pulse ratio (PR) tended to trigger the phenomena of overheat and fracture due to the more intense fluctuation of moisture content, temperature, deformation, and von Mises stress. The model can be extended to simulate the intermittent radio frequency (IRF) process on the basis of which one can select a suitable energy source for a specific process.

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