Determination of Material Characteristic Values in Elastic-Plastic Fracture Mechanics by Means of J-Integral Crack Resistance Curves

1988 ◽  
Vol 16 (1) ◽  
pp. 1 ◽  
Author(s):  
A Wolfenden ◽  
E Roos ◽  
U Eisele
Keyword(s):  
Fracture Mechanics ◽  
Crack Resistance ◽  
J Integral ◽  
Material Characteristic ◽  
Elastic Plastic ◽  
Resistance Curves ◽  
Characteristic Values ◽  
Crack Resistance Curves

Machine learning-based prediction of the translaminar R-curve of composites from simple tensile test of pre-cracked samples

2021 ◽  
pp. 2050017
Author(s):  
Cheng Qiu ◽  
Yuzi Han ◽  
Logesh Shanmugam ◽  
Zhidong Guan ◽  
Zhong Zhang ◽  
...  
Keyword(s):  
Machine Learning ◽  
Fracture Mechanics ◽  
Crack Resistance ◽  
Experimental Studies ◽  
Basalt Fiber ◽  
Learning Model ◽  
Machine Learning Model ◽  
Finite Fracture Mechanics ◽  
Resistance Curves ◽  
Crack Resistance Curves

A novel approach to determine the translaminar crack resistance curve of composite laminates by means of a machine learning model is presented in this paper. The main objective of the proposed method is to extract hidden information of crack resistance from strength values of center-cracked laminates. Compared to traditional measurements, the notable advantage is that only tensile strength values are required which can be obtained by a rather simpler experimental procedure. This is achieved by the incorporation of the finite fracture mechanics, which links crack resistance with strength values. In order to get training dataset, a semi-analytical method using both finite element method and finite fracture mechanics is employed to generate strength values of center-cracked specimens with different random R-curves, which serve as inputs for our artificial neural network. Regarding the outputs, principal component analysis is performed to reduce dimensionality and find suitable descriptors for crack resistance curves. After successfully training machine learning model, experimental studies on basalt fiber reinforced laminates are conducted as validation. Results have proven the effectiveness of the proposed strategy for predicting crack resistance curves, as well as the feasibility of using machine learning-based framework to find out more information about composites from simple experimental data.

A Simple Specimen for the Determination of Elastic-Plastic Fracture Mechanics Parameters on Hollow Cylinders

1989 ◽  
Vol 111 (3) ◽  
pp. 252-258
Author(s):  
E. Roos
Keyword(s):  
Fracture Mechanics ◽  
Linear Elastic ◽  
Arc Shape ◽  
Growth Laws ◽  
Resistance Curves ◽  
Hollow Cylinders ◽  
Elastic Fracture ◽  
Mechanics Characteristics ◽  
Crack Resistance Curves

Functions have been derived for a linear-elastic fracture mechanics specimen of an arc-shape, which because of this shape, can be removed relatively easily from pipes or cylindrical components. These specimens can be used for determining crack resistance curves using the J-integral so that, even for thinner components, it is relatively simple to obtain crack growth laws with crack propagation direction over the wall thickness. The ductile fracture mechanics characteristics determined on arc-shaped specimens corresponds well with the values determined on side-grooved CT-25 specimens.

Limit Strains of X70 Pipes With a Semi-Elliptical Crack Based on Initiation and Ductile Tearing Criteria

2018 ◽  
Author(s):  
Ju-Yeon Kang ◽  
Youn-Young Jang ◽  
Nam-Su Huh ◽  
Ki-Seok Kim ◽  
Woo-Yeon Cho
Keyword(s):  
Crack Initiation ◽  
Crack Resistance ◽  
Crack Growth ◽  
Driving Force ◽  
J Integral ◽  
Resistance Curve ◽  
Crack Driving Force ◽  
Ductile Tearing ◽  
Resistance Curves ◽  
Crack Resistance Curves

Crack-tip opening displacement (CTOD) and J-integral have been used for elastic-plastic fracture parameters as a crack driving force (CDF) and crack resistance curve to evaluate tensile strain capacity (TSC) of cracked pipelines based on strain-based design (SBD). The TSC can be determined by using two kinds of failure criteria. One is based on the limit state corresponding to an onset of stable crack growth and the other is tangency approach which determines an onset of unstable crack growth by comparing crack driving force and resistance curve. For this reason, the accurate calculation of crack driving force and crack resistance curve is highly required to determine TSC. In the present study, the TSCs for X70 pipelines with a circumferential semi-elliptical surface crack were estimated based on both crack initiation and ductile tearing criteria using crack driving force diagram (CDFD) method. The CDF curves of cracked pipelines were calculated through the detailed elastic-plastic finite element (FE) analyses. Crack resistance curves were obtained from experimental data of single edged notch tension (SENT) specimens. Both the CDF and crack resistance curves were represented using CTOD and J-integral, respectively. As for loading conditions, axial strain and internal pressure were considered. The TSCs based on CTOD were compared with those based on J-integral to investigate the effect of choice of the fracture parameters on TSC. From the FE results, the TSCs based on ductile tearing allowed higher TSCs than those based on crack initiation. Although there were some differences between the TSCs using CTOD and J-integral, the effect of choice of fracture parameter on TSC with internal pressure was not significant.

Prediction of Brittle Fracture Under Generalised Elastic Plastic Loading

2008 ◽  
Author(s):  
S. J. Lewis ◽  
C. E. Truman ◽  
D. J. Smith
Keyword(s):  
Fracture Mechanics ◽  
Brittle Fracture ◽  
Ferritic Steel ◽  
Failure Prediction ◽  
J Integral ◽  
Local Approach ◽  
Elastic Plastic ◽  
Failure Data ◽  
Stress States ◽  
Plastic Loading

This article describes an investigation into the ability of a number of different fracture mechanics approaches to predict failure by brittle fracture under general elastic/plastic loading. Data obtained from C(T) specimens of A508 ferritic steel subjected to warm pre-stressing and side punching were chosen as such prior loadings produce considerably non-proportionality in the resulting stress states. In addition, failure data from a number of round notched bar specimens of A508 steel were considered for failure with and without prior loading. Failure prediction, based on calibration to specimens in the as received state, was undertaken using two methods based on the J integral and two based on local approach methodologies.

Experimental evaluation of fracture properties of bovine hip cortical bone using elastic–plastic fracture mechanics

2021 ◽  
pp. 1-10
Author(s):  
Waseem Ur Rahman ◽  
Rafiullah khan ◽  
Noor Rahman ◽  
Ziyad Awadh Alrowaili ◽  
Baseerat Bibi ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Plastic Deformation ◽  
Fracture Mechanics ◽  
Cortical Bone ◽  
Elastic Deformation ◽  
Compact Tension ◽  
J Integral ◽  
Elastic Plastic ◽  
American Society ◽  
Fracture Specimens

BACKGROUND: Understanding the fracture mechanics of bone is very important in both the medical and bioengineering field. Bone is a hierarchical natural composite material of nanoscale collagen fibers and inorganic material. OBJECTIVE: This study investigates and presents the fracture toughness of bovine cortical bone by using elastic plastic fracture mechanics. METHODS: The J-integral was used as a parameter to calculate the energies utilized in both elastic deformation (Jel) and plastic deformation (Jpl) of the hipbone fracture. Twenty four different types of specimens, i.e. longitudinal compact tension (CT) specimens, transverse CT specimens, and also rectangular unnotched specimens for tension in longitudinal and transverse orientation, were cut from the bovine hip bone of the middle diaphysis. All CT specimens were prepared according to the American Society for Testing and Materials (ASTM) E1820 standard and were tested at room temperature. RESULTS: The results showed that the average total J-integral in transverse CT fracture specimens is 26% greater than that of longitudinal CT fracture specimens. For longitudinal-fractured and transverse-fractured cortical specimens, the energy used in the elastic deformation was found to be 2.8–3 times less than the energy used in the plastic deformation. CONCLUSION: The findings indicate that the overall fracture toughness measured using the J-integral is significantly higher than the toughness calculated by the stress intensity factor. Therefore, J-integral should be employ to compute the fracture toughness of cortical bone.

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