Abstract

Conventional sensor structure design and related fracture mechanics analysis are based on the single J-integral parameter approach of elastic-plastic fracture mechanics (EPFM). Under low crack constraint cases, the EPFM one-parameter approach generally gives a stress overestimate, which results in a great cost waste of labor and sensor components. The J-A two-parameter approach overcomes this limitation. To enable the extensive application of the J-A approach on theoretical research and sensor engineering problem, under small scale yielding (SSY) conditions, the authors developed an estimate method to conveniently and quickly obtain the constraint (second) parameter A values directly from T-stress. Practical engineering application of sensor structure analysis and design focuses on three-dimensional (3D) structures with biaxial external loading, while the estimate method was developed based on two-dimensional (2D) plain strain condition with uniaxial loading. In the current work, the estimate method was successfully extended to a 3D structure with biaxial loading cases, which is appropriate for practical sensor design. The estimate method extension and validation process was implemented through a thin 3D single edge cracked plate (SECP) specimen. The process implementation was completed in two specified planes of 3D SECP along model thickness. A wide range of material and geometrical properties were applied for the extension and validation process, with material hardening exponent value 3, 5 and 10, and crack length ratio 0.1, 0.3 and 0.7.

Highlights

  • Fracture mechanics analysis (e.g., [1,2,3]) is significant for engineering structure analysis and design process

  • The estimate method was successfully extended to a 3D structure with biaxial loading cases, which is appropriate for practical sensor design

  • Because of the geometrical symmetry, for both modified boundary layer (MBL) and single edge cracked plate (SECP), only one-quarter of the 3D model is meshed for finite element analysis (FEA), with coordinates the origin set at the crack tip in the middle plane of the 3D model

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Summary

Introduction

Fracture mechanics analysis (e.g., [1,2,3]) is significant for engineering structure analysis and design process. A was developed by the authors [21] under two-dimensional (2D) plain strain condition, and was extended to a three-dimensional (3D) structure with uniaxial external loading [22] It predicts parameter A solutions directly from T-stress values conveniently and quickly, to enable the practical engineering application of T-stress-based estimate method for parameter A. The suggested SSY estimate methodology [21,23] for constraint parameter A will be extended to 3D biaxial external loading condition for sensor structure analysis and design as well as other engineering applications through 3D single edge cracked plate (SECP) specimen analysis. The results in current work will greatly benefit the sensor design process and other engineering applications

J-T and J-A Two-Parameter Approach
T-Stress-Based Estimate of Constraint Parameter A
Material Model and Properties
Finite Element Analysis and Numerical Solutions
1–4. IntoFigures
T-stress-Base Estimate for 3D Structures
Determining Constraint Parameter A for 3D SECP under Biaxial Loading
Validation and Discuss
Findings
Conclusions
Full Text
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