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951.
In this paper, the characteristic properties ofv (y-direction displacement) field surrounding the tip of a mixed mode crack are studied. These properties can be used to evaluate the rigid body rotation of the crack tip, theK
I SIF and the ratio ofK
II SIF toK
I.The authors employ a film to record the displacement information based on the technique of moire interferometry with sticking films. By using the data taken from the moire pattern and treating them with the damping least square method, all of the parameters of the crack can be obtained accurately. 相似文献
952.
953.
Consideration is given to the contact interaction of the faces of a stationary plane elliptical crack under the action of a harmonic shear wave normally incident on the crack surface. The dependence of the mode II and III stress intensity factors on the wave number is studied for different values of the friction coefficient 相似文献
954.
The buckling and post-buckling of clamped circular plate subjected to distributed radial compressed load is presented by using the high-order perturbation analysis and shooting method. The sixth-order solution shows good agreement with the FEM results in [11]. The results in this paper are applied to investigate the buckling and growth of pressed thin film delamination in the film/substrate system. Under a certain residual pressure in the thin film, two characteristic blister radiiR
c andR
g, the critical radius and growing radius respectively, are obtained. The numerical result shows that the growth criterion of delamination in [9,10] is not perfect. In variant residual stress or interface toughness, the conditions of no growth, stable growth and unstable growth of the delamination are obtained by comparing the driving force at the interface crack tip with the interface toughness.This project is supported by National Natural Science Foundation of China. 相似文献
955.
Gerald Pinter Reinhold W. Lang Markus Haager 《Monatshefte für Chemie / Chemical Monthly》2007,138(4):347-355
Summary. The present paper describes the main elements of a novel concept for lifetime and safety assessment of polyethylene pressure
pipes for arbitrary installation conditions based on modern methods of fracture mechanics. At the core of the proposed concept
is the accelerated generation of so-called synthetic crack growth curves and corresponding material laws for crack growth
initiation and slow crack growth for service-near temperature conditions without the use of stress cracking liquids. 相似文献
956.
Experimental studies on dynamic fracture behavior of thin plates with parallel single edge cracks 总被引:1,自引:0,他引:1
Dynamic fracture behavior of polymer PMMA thin plates with three- and four-parallel edge cracks was studied by means of the method of caustics in combination with a high-speed Schardin camera. A series of dynamic caustic patterns surrounding the crack tip and fracture path of the specimen were recorded simultaneously by two types of focused images. Some dynamic fracture parameters such as the dynamic stress intensity factor, crack velocity and acceleration were determined. The evolution of dynamic stress intensity factors on the parallel edge cracks, due to the dynamic unloading effect, was analyzed from the viewpoint of the release of elastic strain energy. 相似文献
957.
Antiplane analysis for an elliptical inclusion in 1D hexagonal piezoelectric quasicrystal composites
An elliptical inclusion embedded in an infinite 1D hexagonal piezoelectric quasicrystal matrix is analysed in the framework of linear piezoelasticity of quasicrystals. Using the technique of conformal mapping, the closed-form solutions of the complex potentials, all the field quantities in the matrix and the inclusion are obtained under far-field antiplane mechanical loads of the phonon and phason fields and an inplane electrical load. Several special cases, such as a homogeneous material, a soft and permeable inclusion, an impermeable inclusion, a line inclusion, a rigid inclusion and a crack are reduced by the present results. Some numerical examples are provided to shows the variations of the stresses of the phonon and phason fields and the electric field with the shape of hole/inclusion, the dielectric permittivity and the distance from the hole/inclusion. 相似文献
958.
Yonglin Xu Ted Belytschko Dept. of Civil Engineering Northwestern University Evanston IL U. S. A 《Acta Mechanica Solida Sinica》1996,9(2):104-123
The Self-Similar Crack Expansion (SSCE) method is proposed to evaluate stress intensi-ty factors at crack tips, whereby stress intensity factors of a crack can be determined by the crackopening displacement over the crack, not just by the local displacement around the crack tip. The crackexpansion rate is estimated by taking advantage of the crack self-similarity. Therefore, the accuracy ofthe calculation is improved. The singular integrals on crack tip elements are also analyzed and are pre-cisely evaluated in terms of a special integral analysis. Combination of these two techniques greatly in-creases the accuracy in estimating the stress distribution around the crack tip. A variety of two-dimen-sional cracks, such as subsurface cracks, edge cracks, and their interactions are calculated in terms ofthe self-similar expansion rate. Solutions are satisfied with errors less than 0.5% as compared with theanalytical solutions. Based on the calculations of the crack interactions, a theory for crack interactionsis proposed such that for a group of aligned cracks the summation of the square of SIFs at the right tipsof cracks is always equal to that at the left tips of cracks. This theory was proved by the mehtod ofSelf-Similar Crack Expansion in this paper. 相似文献
959.
The numerical analyses of stationary mathematically sharp Mode I crack in FCC and BCC crystals with elastic-ideally plastic
(EIP) and fast hardening saturation (FHS) law are carried out in the present paper. From the calculated results, it is shown
that: for the cases of small strain, EIP crystal cracks, the features of concentrated deformation patterns and the stress
state in near-crack tip deformation fields are identical to the earlier analytical solutions, but along the angular sector
boundaries, there exist narrow complex stress zones. The overall characteristics of deformation patterns for the cases of
EIP and FHS are similar. The behaviours of crack tip opening can be characterized by crack-tip-opening-displacement (CTOD).
For the case of FHS, finite deformation BCC crystal crack, our calculations are qualitatively in agreement with recent experimental
observations.
The project supported by National Natural Science Foundation of China 相似文献
960.
This paper is concerned with the propagation of a crack along the interface of a piezoelectric bimaterial, which can travel at subsonic or intersonic speed. The inertial effects are taken into account while the static approximation is applied to the electric fields. The effect of piezoelectricity on the asymptotic crack-tip field is discussed for an interface crack propagating subsonically and intersonically. An alternative method is used to avoid solving for the eigenvectors. This paper provides a unified method to analyze the crack-tip field of a crack propagating along a piezoelectric bimaterial interface. 相似文献