Numerical Simulation of Stress Shielding Induced by Crack Interaction in Human Phalanx Bone

2014 ◽  
Vol 695 ◽  
pp. 584-587
Author(s):  
Siti Aisyah Abdul Halim ◽  
Noor A. Md Zain ◽  
Nurul Najwa Mansor ◽  
Ruslizam Daud ◽  
Y. Bajuri
Keyword(s):  
Numerical Simulation ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Bone Fracture ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Crack Interaction ◽  
Interaction Factor ◽  
Crack Tips

Bone fracture is an injury not uncommon to everyday life. Most of the time, it leaves permanent damage and a long period of recovery. This situation can be prevented if we understand the mechanics and the process of the bone fracture. This study aim is to evaluate stress shielding induced by crack interaction using a simple model based on Linear Elastic Fracture Mechanics (LEFM). This simulation based on the determination of the Stress Intensity Factor (SIF) and the changes of stress shielding in different crack interval towards the human phalanx bone. Numerical simulation had been carried out in this project to understand the stress shielding induced by crack interaction. The results revealed that the interaction of two cracks is directly proportional to the SIF magnitude and interaction factor at the crack tips. The parallel cracks have experienced increasing shielding effect as the crack interval increase. The crack interaction limit (CIL) and crack unification limit (CUL) also had been accomplished for every range of crack interval in this project. Several improvements will be conducted for future development of this study, including various stresses loading subjected to the model, porous element added in the model, different planes of the model and use various methods in calculating the stress intensity factor (SIF).

Influences of Crack Face Bridging Stress and Microstructure on Fracture Toughness of Toughened Alumina Ceramics

2011 ◽  
Vol 462-463 ◽  
pp. 972-978
Author(s):  
Yoshihisa Sakaida ◽  
Hajime Yoshida ◽  
Shotaro Mori
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Opening ◽  
Stress Shielding ◽  
Crack Tip ◽  
Shielding Effect ◽  
Hot Press ◽  
Crack Face

Three types of polycrystalline alumina, one pressureless and two hot press sintered Al2O3, were used to examine the effects of the characteristics of microstructure and crack face bridging on fracture toughness. The crack opening displacements and microstructures along the pop-in crack of single edge precracked beam (SEPB) specimens were observed in situ at a constant applied stress intensity factor by scanning electron microscopy (SEM). The bridging stress distribution could be determined from the measured crack opening displacement by three-dimensional finite element analysis, and then the stress intensity factor and stress shielding effect at the crack tip could also be determined. Intergranular microcracks of toughened Al2O3 were deflected by a complicated microstructure, and crack closure due to bridging grains was observed near the crack tip. Bridging stress of Al2O3 was compressive perpendicular to the crack face and was distributed behind the crack tip. The maximum bridging stress of two hot press sintered Al2O3 was about twice as large as that of pressureless sintered Al2O3. The fracture toughness of hot press sintered Al2O3 was, therefore, higher than that of pressureless sintered Al2O3, because the total amount of bridging stress and stress shielding effect increased with increasing magnitude of microcrack deflection and the number of interlocking grains.

Numerical Simulation of Coalescence Behavior of Multiple Surface Cracks

2011 ◽  
Author(s):  
Masanori Kikuchi ◽  
Yoshitaka Wada ◽  
Kazuhiro Suga ◽  
Chikako Ohdama
Keyword(s):  
Numerical Simulation ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Experimental Studies ◽  
Multiple Cracks ◽  
Surface Cracks ◽  
Crack Tips

Study on the interaction of multiple cracks during fatigue crack growth processes is important for the integrity evaluation of nuclear structure. By using S-version FEM, this problem has been simulated by authors. In this study, coalescence behavior of 2 surface cracks is simulated using the method. It is assumed that 2 surface cracks exist on the same plane, and grow towards each other by fatigue. As the inner crack tips overlap, coalescence of 2 cracks occurs, and shape of cracks change significantly over very short cycles. This process is simulated in detail, and changes of stress intensity factor distributions along crack front are studied precisely. Three cases of changing crack sizes are simulated and coalescence behaviors are studied. Experimental studies are also conducted and results are compared with those of numerical simulations. Results are compared with conventional evaluation code and discussed.

Variation of Stress Intensity Factor and Crack Distance Length for Double Edge Crack in Human Femur Bone

2014 ◽  
Vol 695 ◽  
pp. 580-583
Author(s):  
Noor A. Md Zain ◽  
Ruslizam Daud ◽  
W.Z.A.W. Muhamad ◽  
Khairul Salleh Basaruddin ◽  
Yazid Bajuri ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Parallel Edge ◽  
Linear Elastic ◽  
Femur Bone ◽  
Double Edge ◽  
Crack Tips ◽  
Elastic Fracture ◽  
Edge Cracks

The theory of linear elastic fracture mechanic (LEFM) has proven that we can evaluate the amount of stress located at the crack tip by determining the stress intensity factor (). The stress at the tip of a sharp crack has the highest stress which can lead to failure on the material. Thus, the cracks within human bones are quite complicated because of the bone microstructure. There are a few factors that can minimize the effect of the cracks so that patients can heal much faster. Hence, this paper focuses on how several crack distances, between two parallel edge cracks can affect the value of stress intensity factor (). Using the LEFM theory, the interaction between two neighboring crack tips was investigated.

Fracture Analysis for Stiffened Aircraft Fuselage Subjected to Blast

2009 ◽  
Vol 417-418 ◽  
pp. 661-664
Author(s):  
Jin San Ju ◽  
Xin Yu Yao ◽  
Ding Min ◽  
Xiu Gen Jiang
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Dynamic Stress ◽  
Dynamic Stress Intensity Factor ◽  
Longitudinal Crack ◽  
Blast Load ◽  
Aircraft Fuselage ◽  
Calculation Results ◽  
Crack Tips

This paper primarily presents the automation computational analysis techniques to determine the dynamic stress intensity factor for the stiffened damaged aircraft fuselage subjected to triangle blast load. 3-dimention panel models can be created using parameterization and the dynamic stress intensity factor can be obtained in the procedure of the blast automatically. A typical stiffened curved panel model which consists of 7 frames and 8 stringers is calculated. The calculation results show that the peak SIF value of the crack in the panel with strips under blast load is always smaller than that without strips for all longitudinal crack lengths; the strips can slow down the crack growth markedly and the effect of the strips on SIF is most obvious when the crack tips are close to the edge of strips; the blast load time has effect on the SIF peak value, and the effect is most significant when the load time is about 25 milliseconds for the panel with strips.

Fatigue crack propagation experiment and numerical simulation of 42CrMo steel

2020 ◽  
Vol 234 (14) ◽  
pp. 2852-2862
Author(s):  
Jianwei Dong ◽  
Weichi Pei ◽  
Hongchao Ji ◽  
Haiyang Long ◽  
Xiaobin Fu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Crack Tip ◽  
42Crmo Steel ◽  
Crack Tip Stress

42CrMo steel is widely used in ultrahigh-strength structures such as low-speed heavy-duty gears. Mastering the fatigue crack propagation law has important significance for predicting structural fatigue life. Firstly, the fatigue crack propagation experiment is used to obtain the upper and lower thresholds value of type I fatigue crack propagation of 42CrMo steel compact tensile specimen under the alternating load of stress ratio R = 0.1. The Paris formula describing the relationship between the fatigue crack propagation rate and the crack tip stress intensity factor between the upper and lower thresholds value is obtained. Scanning electron microscopy was used to observe the microscopic features of different stages of fatigue fracture. The results show that the twin boundary can provide a place for crack initiation; the defects in the material can promote the initiation and extension of fatigue cracks. The fatigue crack propagation of 42CrMo steel compact tensile specimens was numerically simulated by the finite element method. The relationship between the crack tip stress intensity factor and the crack length was obtained. The analysis results show that the crack tip stress intensity factor calculated by the plane finite element method differs slightly from the experimental results during the stable extension stage. After correction, the correlation coefficient between the numerical simulation correction value and the crack tip stress intensity factor value obtained by the experiment is 0.9926. Finally, the fatigue crack propagation rate corresponding to the crack tip stress intensity factor in the finite element results is calculated by the Paris formula and briefly analyzed. Compared with the experimental results, it shows that the numerical simulation is consistent with it, indicating the accuracy of the numerical simulation method, which can effectively predict the initiation and propagation of fatigue cracks in 42CrMo steel compact tensile specimens.

Sign in / Sign up

Export Citation Format

Share Document