The effect of contact conditions and the gap between the metal and composite layers on the stress-strain state and strength of a two-layer metal composite cylinder under internal explosive loading in air is numerically studied. It is accepted that in the absence of a gap between the metal and composite layers, there is no interference. The problem was considered on the basis of the general equations of theories of elasticity and plasticity in a one-dimensional formulation (plane strain state), which makes it possible to neglect the peculiarities of loading and deformation along the cylinder length. In the absence of an initial gap, the case of perfect contact between the layers was also studied. The inner layer is made of one or another isotropic elastoplastic steel with significantly different yield strengths (steels 20 and 40KhNMA), the outer one is made of an elastic-to-failure cylindrically transtropic circumferentially reinforced composite The dynamic 1D boundary-value problem was solved using the training version of the LS-DYNA software, which is part of the ANSYS commercial application package. The solution method is the Wilkins finitedifference integro-interpolation algorithm included in above software version. It has been established that the strength of the metal composite cylinder under internal explosion is determined by the strength of the outer composite layer under tension in the radial direction and depends nonlinearly and nonmonotonically on the initial gap between the layers. The maximum strength is realized under perfect or non-perfect contact with zero initial gap, and the minimum strength is realized at the initial gap that is roughly equal to a half of the maximum displacement of the inner steel shell in the case of absence of the outer composite layer. To make the reinforcing inner layer, it is inexpedient to use, in terms of strength, structural alloy steels with high yield strength; the steels with low yield strength are more efficient.

中文翻译：

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内爆条件下层间间隙对两层金属复合材料圆柱体动力学和强度的影响

数值研究了内部爆炸载荷作用下接触条件和金属与复合层之间的间隙对两层金属复合圆柱体应力应变状态和强度的影响。公认的是，在金属层和复合层之间没有间隙的情况下，没有干扰。基于一维公式（平面应变状态）中的弹性和塑性理论的一般方程式来考虑该问题，这使得可以忽略沿圆柱体长度的载荷和变形的特殊性。在没有初始间隙的情况下，还研究了层之间完美接触的情况。内层由一种或另一种各向同性的弹塑性钢制成，其屈服强度（钢20和40KhNMA）明显不同，外部是由弹性至失效的圆柱形横贯圆周增强复合材料制成。使用一版的LS-DYNA软件解决了动态一维边界值问题，该软件是ANSYS商业应用程序包的一部分。解决方法是上述软件版本中包含的Wilkins有限差分整数插值算法。已经确定，金属复合材料圆柱体在内部爆炸下的强度由外部复合材料层在径向上的拉伸强度决定，并且非线性且非单调地取决于层之间的初始间隙。在零间隙的完美或非完美接触下实现最大强度，在没有外部复合层的情况下，最小强度在初始间隙处实现，该初始间隙大约等于内部钢壳最大位移的一半。为了制造增强内层，就强度而言，使用具有高屈服强度的结构合金钢是不合适的。屈服强度低的钢效率更高。