Dynamic Finite Element Analyses of Two Compact Specimens

1978 ◽  
Vol 100 (4) ◽  
pp. 402-410 ◽  
Author(s):  
A. S. Kobayashi ◽  
Y. Urabe ◽  
S. Mall ◽  
A. F. Emery ◽  
W. J. Love
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Arrest ◽  
Compact Specimen ◽  
Intensity Factors ◽  
Dynamic Stress Intensity Factors ◽  
Additional Energy ◽  
Dynamic Finite Element ◽  
Loading System

A dynamic finite element code was used to compute the dynamic stress intensity factors and crack arrest stress intensity factors which are related to the crack run-arrest responses in longitudinal and transverse wedge-loaded compact specimens machined from A533B and 1018 steels, respectively. Measured crack velocities were used to prescribe crack motions in the longitudinal and transverse wedge-loaded compact specimens under fixed wedge displacements. The numerical analyses show that approximately 45 percent additional energy is input during the crack propagation phase in the former compact specimen while the rigid loading system in the latter results in essentially quasi-static crack extension.

Elastodynamic Fracture Analysis of Multiple Cracks by Laplace Finite Element Alternating Method

1999 ◽  
Vol 67 (3) ◽  
pp. 606-615 ◽  
Author(s):  
W.-H. Chen ◽  
C.-L. Chang ◽  
C.-H. Tsai
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Laplace Transform ◽  
Stress Intensity Factors ◽  
Dynamic Stress ◽  
Multiple Cracks ◽  
Intensity Factors ◽  
Dynamic Stress Intensity Factors ◽  
Alternating Method ◽  
The Laplace Transform

The Laplace finite element alternating method, which combines the Laplace transform technique and the finite element alternating method, is developed to deal with the elastodynamic analysis of a finite plate with multiple cracks. By the Laplace transform technique, the complicated elastodynamic fracture problem is first transformed into an equivalent static fracture problem in the Laplace transform domain and then solved by the finite element alternating method developed. To do this, an analytical solution by Tsai and Ma for an infinite plate with a semi-infinite crack subjected to exponentially distributed loadings on crack surfaces in the Laplace transform domain is adopted. Finally, the real-time response can be computed by a numerical Laplace inversion algorithm. The technique established is applicable to the calculation of dynamic stress intensity factors of a finite plate with arbitrarily distributed edge cracks or symmetrically distributed central cracks. Only a simple finite element mesh with very limited number of regular elements is necessary. Since the solutions are independent of the size of time increment taken, the dynamic stress intensity factors at any specific instant can even be computed by a single time-step instead of step-by-step computations. The interaction among the cracks and finite geometrical boundaries on the dynamic stress intensity factors is also discussed in detail. [S0021-8936(00)02103-6]

Use of Jˆ-Integral in Dynamic Analysis of Cracked Linear Viscoelastic Solids by Finite-Element Method

1982 ◽  
Vol 49 (1) ◽  
pp. 75-80 ◽  
Author(s):  
K. Kishimoto ◽  
S. Aoki ◽  
M. Sakata
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Dynamic Stress ◽  
Dynamic Stress Intensity Factor ◽  
Computational Method ◽  
Intensity Factors ◽  
Dynamic Stress Intensity Factors ◽  
Element Method

A computational method using the path (area)-independent Jˆ-integral is developed to analyze viscoelastic problems. Since the displacement field near the crack tip of a viscoelastic solid is dependent upon the complete past history of the dynamic stress-intensity factors, the Jˆ-integral is represented by a hereditary integral of the dynamic stress-intensity factors. We assume that the stress and strain rates vary in proportion to time during each increment of time and derive a formula to obtain the current value of the dynamic stress-intensity factor from the time increment of the Jˆ-value. Both pure and mixed mode problems of a suddenly loaded crack are analyzed by making use of the formula together with the conventional finite-element method. In order to demonstrate the capability and reliability of the present method, problems of a center crack and an oblique crack in viscoelastic rectangular plates are solved.

A compact mixed-mode (cmm) fracture specimen

1988 ◽  
Vol 23 (2) ◽  
pp. 61-66 ◽  
Author(s):  
T H Hyde ◽  
A C Chambers
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Mixed Mode ◽  
Static Fatigue ◽  
Intensity Factors ◽  
Integral Methods ◽  
Fracture Specimen ◽  
Loading System ◽  
Creep Fatigue

A practical, compact mixed-mode (CMM) fracture specimen, which can be used for any combination of mode-I and mode-II stress intensities, is described. The loading system, which is suitable for high temperature testing, is also described. The specimen can be used for mixed-mode testing under static, fatigue, creep, or creep/fatigue conditions. The stress-intensity factors ( KI and KII) for the complete range of loading conditions have been obtained by finite element and photoelastic methods. Nodal displacement, stress, and contour integral methods, using the finite element results all gave practically the same stress intensity factors. These were in reasonably close agreement with the results obtained using shear stress distributions obtained from the photoelastic tests.

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