Thermoelastic-numerical hybrid analysis of holes and cracks in composites

An effective thermoelastic-numerical hybrid method is demonstrated for obtaining stress information on, and adjacent to, geometric discontinuities in orthotropic composites. This includes determining stress intensity factors. The technique involves evaluating the stress functions from measured thermoelastic data around the external boundary of a subregion containing the geometric discontinuity of interest. Knowing the stress functions, stresses throughout the subregion surrounding the geometric discontinuity, and stress intensity factors, are available.     

Stress-intensity distributions for corner cracks emanating from open holes in plates of finite width

A series of frozen stress photoelastic tests is carried out in the present investigation. Linear Elastic Fracture Mechanics is used to analyze the problem of a part-through corner crack at an open hole in a plate of finite width loaded in tension. The photoelastic modeling capability of three-dimensional subcritical crack growth problems is assessed. This is achieved by comparing monotonically grown flaw shapes in epoxy models with crack profiles relative to fatigue crack propagation tests in a different material. Photoelastic stress-intensity factor distributions are checked against numerical results obtained for quarter elliptical geometries. The dependence of stress intensity factors on flaw shape is also discussed.     

Electromagnetoelastic problem for a plate with holes and cracks

The methods of complex potentials, conformal mappings, and least squares are used to solve a plane problem of electromagnetoelasticity for a plate with holes and cracks. Numerical solutions are found for a ring and a disk with a crack under internal concentrated forces or electric charges as well as electric potentials applied to the boundaries     

正交异性平面内的椭圆孔或裂纹系问题

应用Ｆａｂｅｒ级数展开和各向异性体平面问题复应力函数的方法，对于含有任意个椭圆孔或裂纹的正交异性平面，给出了孔周应力场解或孔附近裂纹应力强度因子解，其特例与前人结果一致．     

Determination of stress intensity factors at the tips of cracks growing from loaded holes in finite anisotropic plates

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 171–177, March–April, 1990.     

Thermal stress state near edge cracks in a plane with elliptical holes

S. P. Timoshenko Institute of Mechanics of National Academy of Sciences of Ukraine, Kiev. Poltava Agricultural Institute, Poltava. Translated from Prikladnaya Mekhanika, Vol. 31, No. 11, pp. 90–96, November, 1995.     

Problems of electromagnetoelasticity for a half-plane and a strip with holes and cracks

The methods of complex potentials, conformal mappings, Cauchy integrals, and least-squares are used to develop a method for determining the electromagentoelastic state (EMES) of a multiply connected half-plane, with the boundary conditions on the straight-line boundary satisfied exactly. The method underlies an approximate method for determining the EMES of a strip with arbitrarily arranged holes and cracks. The dependence of the EMES on the geometrical parameters of a strip with a circular hole or a crack is analyzed     

Stress wave fields in plates weakened by curvilinear holes with edge cracks

The dynamic fracture of plates weakened by holes with edge cracks and subjected to impulsive loading is studied using the dynamic photoelastic method. The time dependences of the stress intensity factors and the crack growth rate are examined for three models of plates with circular holes and edge cracks __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 2, pp. 79–84, February 2006.     

Integral equations for any configuration of curved cracks and holes in an elastic strip

Summary A method is presented to deal with the problems of an elastic strip weakened by cracks and holes of any configuration and geometry. The solution in terms of complex potentials is given by integrals over the cracks and holes with integrands expressed in terms of determined functions (Green) and an unknown density function (t). A singular integral equation for the complex density function (t) is derived for the problem. The appropriate Green's functions are derived from the solution for the problem of an uncracked strip subjected to a concentrated force or a dislocation. The integral equation is solved numerically for a strip in tension with an internal circular arc crack.

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Integralgleichungen für beliebige Konfigurationen von gekrümmten Rissen und Löchern in einer elastischen Scheibe

Übersicht Eine Methode wird dargestellt, welche zur Lösung von Problemen einer unendlichen elastischen Scheibe endlicher Breite mit Rissen und Löchern beliebiger Konfiguration und Geometrie geeignet ist. Die Lösung in Form von komplexen Spannungsfunktionen wurde mit Hilfe von Integralen über den Rissen und Löchern gegeben. Die Integranden wurden mit Hilfe von bekannten Funktionen (Green) und einer unbekannten Dichtefunktion (t) ausgedrückt, für welche eine singuläre Integralgleichung abgeleitet wurde. Die geeigneten Greenschen Funktionen wurden von der Lösung des Problems der entsprechenden Scheibe ohne Risse, welche mit einer Einzelkraft belastet wird oder eine Versetzung enthält, hergeleitet. Die singuläre Integralgleichung wurde numerisch für eine Scheibe endlicher Breite mit einem Kreisbogenriß im einachsigen Zugspannungsfeld gelöst.

     

任意多孔多裂纹板的裂纹闭合接触分析

基于摩擦接触问题的数学规划解法，采用各向异性体平面弹性理论中的复势方法，建立了含多椭圆孔及裂纹群有限大各向异性板，在任意载荷作用下裂纹闭合或局部闭合问题的有效分析方法。通过在可能闭合的裂纹边界引入互补变量函数并将其展成Fourier级数形式，以Faber级数为工具，应用保角映射技术和最小二乘边界配点法，导出无卸载情况下裂纹面摩擦接触的线性互补模型，并通过算例验证了方法的有效性。数值结果表明，由于采用级数解描述板应力场和位移场，该方法具有较高的计算精度和效率，便于研究裂纹闭合对应力强度因子等断裂参数的影响。     

The method of caustics for static plane elasticity problems

By use of the complex stress function analysis of Muskhelishvili-Kolosov and conformal mapping procedures the general governing equations of the method of caustics or shadow spot technique have been developed for optically isotropic and anisotropic materials in static plane elasticity theory. Special cases of caustics formed about cutouts, cracks, and various singular regions in static elastic stress fields are obtained upon specialization.     

The effects of surface topography on the method of caustics

An investigation was performed to establish the effects of surface topography on the determination of stress intensity factors of opaque components using the method of caustics. Theoretical predictions of caustics produced by curved surfaces were generated and validated by experiment. The errors introduced for stress intensity factors determined at various radii of curvature were assessed. It was found that relatively small surface curvatures caused significant errors in the stress intensity factor. These errors were affected by the initial radius, load and material properties.