Computing Tire Component Durability via Critical Plane Analysis

2019 ◽  
Vol 47 (1) ◽  
pp. 31-54 ◽  
Author(s):  
William V. Mars ◽  
Yintao Wei ◽  
Wang Hao ◽  
Mark A. Bauman
Keyword(s):  
Strain Energy ◽  
Fatigue Behavior ◽  
Stress Singularity ◽  
Crack Development ◽  
Fatigue Threshold ◽  
Critical Plane ◽  
Plane Analysis ◽  
Scalar Invariant ◽  
Edge Separation ◽  
Design Guidance

ABSTRACT Tire developers are responsible for designing against the possibility of crack development in each of the various components of a tire. The task requires knowledge of the fatigue behavior of each compound in the tire, as well as adequate accounting for the multiaxial stresses carried by tire materials. The analysis is illustrated here using the Endurica CL fatigue solver for the case of a 1200R20 TBR tire operating at 837 kPa under loads ranging from 66 to 170% of rated load. The fatigue behavior of the tire's materials is described from a fracture mechanical viewpoint, with care taken to specify each of the several phenomena (crack growth rate, crack precursor size, strain crystallization, fatigue threshold) that govern. The analysis of crack development is made by considering how many cycles are required to grow cracks of various potential orientations at each element of the model. The most critical plane is then identified as the plane with the shortest fatigue life. We consider each component of the tire and show that where cracks develop from precursors intrinsic to the rubber compound (sidewall, tread grooves, innerliner) the critical plane analysis provides a comprehensive view of the failure mechanics. For cases where a crack develops near a stress singularity (i.e., belt-edge separation), the critical plane analysis remains advantageous for design guidance, particularly relative to analysis approaches based upon scalar invariant theories (i.e., strain energy density) that neglect to account for crack closure effects.

LOW CYCLE FATIGUE BEHAVIOR AND LIFE PREDICTION OF A CAST COBALT-BASED SUPERALLOY

2012 ◽  
Vol 06 ◽  
pp. 251-256
Author(s):  
HO-YOUNG YANG ◽  
JAE-HOON KIM ◽  
KEUN-BONG YOO
Keyword(s):  
Fatigue Life ◽  
Strain Energy ◽  
Life Prediction ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Different Temperatures

Co -base superalloys have been applied in the stationary components of gas turbine owing to their excellent high temperature properties. Low cycle fatigue data on ECY-768 reported in a companion paper were used to evaluate fatigue life prediction models. In this study, low cycle fatigue tests are performed as the variables of total strain range and temperatures. The relations between plastic and total strain energy densities and number of cycles to failure are examined in order to predict the low cycle fatigue life of Cobalt-based super alloy at different temperatures. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

scholarly journals Topology Optimization Using Parabolic Aggregation Function with Independent-Continuous-Mapping Method

2013 ◽  
Vol 2013 ◽  
pp. 1-18
Author(s):  
Tie Jun ◽  
Sui Yun-kang
Keyword(s):  
Topology Optimization ◽  
Strain Energy ◽  
Stress Singularity ◽  
Continuous Mapping ◽  
Stress Constraints ◽  
Aggregation Function ◽  
Sensitivity Analyses ◽  
Stress Concentrations ◽  
Filter Function ◽  
Design Variables

This paper concentrates on finding the optimal distribution for continuum structure such that the structural weight with stress constraints is minimized where the physical design domain is discretized by finite elements. A novel Independent-Continuous-Mapping (ICM) method is proposed to convert equivalently the binary design variables which is used to indicate material or void in the various elements to independent continuous design variables. Moreover, three smooth mappings about weight, stiffness, and stress of the structural elements are introduced to formulate the objective function based on the so-called concepts of polish function and weighting filter function. A new general continuous approach for topology optimization is given which can eliminate the stress singularity phenomena more efficiently than the traditionalε-relaxation method, and an alternative strain energy method for the stress constraints is proposed to overcome the difficulty in stress sensitivity analyses. Mathematically, by means of a generalized aggregation KS-like function defined as the parabolic aggregation function, a topology optimization model is formulated with the weight objective and single parabolic global strain energy constraints. The numerical examples demonstrate that the proposed methods effectively remove the stress concentrations and generate black-and-white designs for practically sized problems.

A Low Cycle Fatigue Life Prediction Model of Single Crystal Nickel-Based Superalloys Using Critical Plane Approach Combined With Crystallographic Slip Theory

2017 ◽  
Author(s):  
Lijuan Mu ◽  
Xuezhi Dong ◽  
Qing Gao ◽  
Yongsheng Tian ◽  
Chunqing Tan
Keyword(s):  
Fatigue Life ◽  
Single Crystal ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Complex Stress State ◽  
Critical Plane ◽  
Crystallographic Slip ◽  
Critical Plane Approach ◽  
Life Model

The anisotropy is the most remarkable characteristic for single crystal nickel-based superalloys, which makes fatigue behavior and life prediction highly correlate with the crystallographic orientation. Based on critical plane approach and preferred crystallographic slip mechanism, an anisotropic LCF life model is proposed to account for orientation-dependent fatigue life in this paper. In addition, the effects of the mean stress and stress-weakening caused by asymmetric loading are also considered. The critical plane is determined by searching for 30 potential slip systems. Moreover, the slip plane with the maximum resolved shear stress amplitude in the crystallographic microstructure of the single crystal nickel-based superalloy is chosen as the critical plane. The LCF test data are utilized to obtain the regression equation by multiple linear fitting method. The presented LCF life model is applicable for more complex stress state and has higher prediction accuracy than the CDY model.

Prediction of the path of unstable extension of internal and edge cracks

1980 ◽  
Vol 15 (4) ◽  
pp. 183-194 ◽  
Author(s):  
S K Maiti
Keyword(s):  
Energy Density ◽  
Tangential Stress ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Experimental Studies ◽  
Stress Singularity ◽  
Maximum Tangential Stress ◽  
Stress Criterion ◽  
Maximum Tangential Stress Criterion ◽  
Edge Cracks

The criteria of strain energy density and maximum tangential stress have been applied to the entire stress field existing just before the onset of instability to predict the path of extension of both internal and edge cracks. The stress analysis has been carried out by a finite-element scheme employing the quarter point square-root stress singularity elements. In the case of internal cracks, the unstable paths based on both the criteria are in good agreement with the results available in the literature. Theoretical and experimental studies on edge crack extensions during bar shearing of brittle materials have facilitated a comparison, and it appears that, although the maximum tangential stress criterion may be applicable, the strain energy density criterion is unsuitable for this case.

scholarly journals Fatigue behavior of Nitinol medical devices under multi-axial non-proportional loads

2019 ◽  
Vol 300 ◽  
pp. 12001
Author(s):  
Francesca Berti ◽  
Pei-Jiang Wang ◽  
Andrea Spagnoli ◽  
Carlo Guala ◽  
Francesco Migliavacca ◽  
...  
Keyword(s):  
Fatigue Behavior ◽  
Axial Loading ◽  
Fatigue Behaviour ◽  
Metal Fatigue ◽  
Axial Loads ◽  
Critical Plane ◽  
Stent Restenosis ◽  
Load Combination ◽  
Numerical Predictions ◽  
Von Mises

Nickel-Titanium alloys (Nitinol) are widely used for biomedical applications. Peripheral stents are almost exclusively composed of Nitinol, as its superelasticity is suited for minimally-invasive insertion and durable effect. After crimping and deployment stents undergo cyclic multi-axial loads imposed by vascular and lower-limb motion (e.g. axial compression, bending, and torsion). This complex mechanical environment could lead to metal fatigue and device fracture, with possible severe consequences (e.g. in-stent restenosis). Standard regulations require experimental verification of stent fatigue behaviour for preclinical assessment, but no exact indications are provided to direct the load combination. Moreover, different fatigue criteria were developed for common metals to predict fatigue endurance, but no criteria were specifically defined for the unique thermo-mechanical properties of Nitinol. This study investigated the role of cyclic multi-axial loading conditions on different stent geometries, looking at how they affect the stress/strain distribution along the device and how different criteria may affect the fatigue prediction (e.g. the standard Von Mises alternate approach and other critical plane approaches). Then, a preliminary experimental fatigue campaign was performed in agreement with the numerical simulations in order to compare the numerical predictions with the experimental results. The result suggest that the critical plane approaches are more reliable than the standard Von Mises criterion.

scholarly journals Interaction Between Normal and Shear Stresses and Its Effect on Multiaxial Fatigue Behavior

2019 ◽  
Vol 300 ◽  
pp. 16007 ◽  
Author(s):  
Shahriar Sharifimehr ◽  
Ali Fatemi
Keyword(s):  
Normal Stress ◽  
Fatigue Damage ◽  
Shear Failure ◽  
Fatigue Behavior ◽  
Damage Model ◽  
Multiaxial Fatigue ◽  
Experimental Program ◽  
Shear Stresses ◽  
Critical Plane ◽  
Normal And Shear Stresses

Interaction between normal and shear stresses plays an important role in multiaxial fatigue damage. The aim of this study was to investigate this interaction effect on fatigue behavior of shear failure mode materials under multiaxial loading conditions. In order to model the influence of normal stress on fatigue damage, the present study introduces a method based on the idea that the normal stress acting on the critical plane orientation causes two types of influence, first by affecting roughness induced closure, and second, by a fluctuating normal stress affecting the growth of small cracks in mode II. The summation of these terms could then be used in shear-based critical plane damage models, for example FS damage model, which use normal stress as a secondary input. In order to investigate the effect of the method, constant amplitude load paths with different levels of interaction between the normal and shear stresses were designed for an experimental program. The proposed method was observed to result in improved fatigue life estimations where significant interactions between normal and shear stresses exist.

Fracture and Fatigue of Refractory Metal Intermetallic Composites

1998 ◽  
Vol 552 ◽  
Author(s):  
William A. Zinsser ◽  
Sergey Solv'yev ◽  
John J. Lewandowski
Keyword(s):  
Fatigue Crack ◽  
Fatigue Behavior ◽  
Growth Characteristics ◽  
Fatigue Threshold ◽  
Metallic Materials ◽  
Threshold Values ◽  
In Situ Composites ◽  
Loading Rates ◽  
Paris Law

The fracture and fatigue crack growth characteristics of niobium silicide/Nb(ss) in-situ composites as well as a variety of Nb alloys were determined over a range of temperatures and loading rates. It is shown that the in-situ composites exhibited nominally rate-independent and temperatureindependent values for the toughness with an average toughness exceeding 24 MPa.m0.5. The fatigue behavior of both the Nb alloys and in-situ composites revealed that both the Paris Law exponents and fatigue threshold values were similar to that exhibited by metallic materials.

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