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71.
Results of metal testing in impact tension–compression and indentation are analyzed. As the analysis of these data demonstrates, the strength of metals increases greatly with strain rates and at moderate indentation rates. At high indentation rates, a decrease in the specific energy (per unit volume of a displaced material) necessary for the formation of a conical cavity was observed. The account of the effects of viscosity, temperature increase upon plastic deformation and its localization can be used to explain the above phenomena. 相似文献
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K.W. Allen S.M. Smith W.C. Wake A.O. van Raalte 《International Journal of Adhesion and Adhesives》1985,5(1):23-32
The effect of cyclic stressing on the strength of single lap adhesive joints has been studied and a considerable reduction in strength observed when the maximum stress exceeds about 40% of the ultimate tensile strength, but whether or not a true endurance limit exists is not proven. Fallacies are shown in some of the techniques which have been proposed for studying the fatigue behaviour of adhesive joints. 相似文献
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G. Biallas Dr.‐Ing. C. Sick J. Schneider K.‐H. Trautmann 《Materialwissenschaft und Werkstofftechnik》2007,38(9):705-711
Biaxial fatigue of friction stir welded stiffened panels Within the framework of the European WelAir project, cruciform specimens made from stiffening FSW overlap joints were fatigued in the DLR biaxial test rig. To resemble the loading situation of pressurized fuselage structures, proportional loading without any phase shift, but with different load ratios λ between the loading components in both directions was applied.Natural crack initiation and subsequent crack growth were governed by the stiffness gradient caused by introducing the stringer. Cracks initiated and propagated at run‐in and run‐out locations in a direction perpendicular to the weld seam. The shortest fatigue life was observed for uniaxial loading in welding direction (λ = 0). An additional stress component perpendicular to the joint line (λ > 0) resulted in a higher number of cycles to failure. Similar to single stringer panels, increasing the load ratio also increased the number of cycles to failure for FSW clip‐stringer structural members, but additionally gives a different location of the fatal crack. 相似文献
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对于套管挤毁问题较为严重的油气水井,采用非API标准的特厚壁套管来提高其抗挤强度,是今后预防套管挤毁的重要发展方向。目前,特厚壁套管的抗挤强度计算和尺寸系列尚未形成工业标准,文章提出特厚壁套管的抗挤强度计算方法和尺寸系列,供设计者和厂家参考。API/ISO套管挤毁工作组曾对本文公式进行了测评,结果曼示具有较高的计算精度。大量计算表明,特厚壁套管的抗挤强度大大提高,约为加厚前原套管抗挤强度的1.5~4倍,甚至6倍。最后还介绍了特厚壁套管在中原油田的现场应用情况。 相似文献
79.
The concept that plasticity index of soils can be defined as a range of water contents producing a 100-fold variation in undrained shear strength has been experimentally verified with the help of a large number of tests on soils of diverse nature. This has led to the redefinition of the plastic limit as the water content at which undrained shear strength is around 170 kN/m2. Undrained shear strength of a soil at the liquid limit can be considered to be around 1.7 kN/m2. Accordingly, both the liquid limit and the plastic limit have been determined in the present work by a single consistent method, i.e., the Swedish fall cone method. The undrained shear strength-water content relationship has been found to be log-linear for a wide range of water contents beginning from lower than the plastic limit to higher than the liquid limit. This resulted in the formulation of an expression for predicting undrained shear strength of a remolded soil at any water content based solely on its liquid limit and plastic limit. 相似文献
80.