تحليل تنش پادصفحه‌يي صفحه‌ي بي‌نهايت حاوي چندين ترك براساس نظريه‌ي كشساني غيرموضعي

Anti-Plane Stress Analysis of Multiple Cracks in an Infinite Plane in Nonlocal Theory

در تحقيق حاضر با استفاده از حل نابه‌جايي پادصفحه‌يي در صفحه‌ي بي‌نهايت، و نيز با استفاده از نظريه‌ي توزيع نابه‌جايي، ميدان تنش پاد‌صفحه‌يي اطراف ترك ارايه شده است. ميدان تنش در نوك نابه‌جايي هيچ‌گونه تكينگي ندارد كه با نتايج نظريه‌ي همخواني دارد. به‌همين ترتيب حل ترك در صفحه‌ي بي‌نهايت نيز داراي هيچ‌گونه تكينگي در نوك ترك نيست و مقدار تنش در نوك ترك مشخص است. چند مثال عددي براي نشان دادن صحت و قابليت روش حل مسيله ارايه شده است كه اثر طول ترك، پارامتر شبكه به‌همراه يك ثابت عددي در پارامتر غيرموضعي به‌عنوان متغيري كه در برگيرنده‌ي همه‌ي آن‌هاست لحاظ شده است. نمودار تنش در نوك ترك و خارج آن رسم شده و نتايج به دست آمده با نتايج كلاسيك در اين زمينه مقايسه شده است.

All materials are made up of sub-bodies, which constitute their substructure or microstructure. The size of a sub-body may vary from atomic dimensions to a macroscopic scale, such as grain size. Depending upon the nature and accuracy of the physical phenomena to be modeled, the average distance of the sub-bodies plays a central role. This distance may vary from the order of the lattice parameter (10-8 cm in perfect crystals), to a few millimeters, as in granular solids. The boundary and initial conditions bring into play another characteristic, length. Such models, entitled nonlocal theories, have been proposed for the past four decades. The solutions of various critical problems have verified our hopes and expectations in that, by means of nonlocal models, it will be possible to make accurate predictions of physical phenomena at submicroscopic scale. In the present study, the anti-plane stress field of multiple cracks is obtained using the solution of screw dislocation in an infinite elastic plane, based on nonlocal elasticity. The distribution dislocation technique is used to model the crack problem with screw dislocation distribution. Unlike the classical elasticity solution, a lattice parameter enters into the problem, which makes the stresses finite in the screw dislocation solution in the infinite elastic plane in nonlocal theory, which has no singularity at the dislocation tip, and which is consistent with theoretical results. Similarly, the crack problem using the distribution dislocation theory is solved with no singularity at the crack tip. The kernel in the related equation is of the Cauchy type, and to determine the distribution of dislocations, which generates traction along the crack line, the Gauss-Chebyshev quadrature has been used. Several numerical examples to illustrate the accuracy and capability of the solution have been calculated, where the effect of crack length, lattice parameter and constant is calculated as a variable parameter, which includes all of them. Stress at the crack tip and its graphs are depicted and the results obtained are compared with classical results in this field.