304L/Q235B大面积金属板爆炸焊接物质点法模拟分析

大面积金属板材304L/Q235B的爆炸焊接过程涉及炸药爆轰、金属板材的高速碰撞和塑性变形等。采用有限元法计算模拟这个问题时，网格单元会发生扭曲畸变现象，导致计算精度下降，甚至出现单元负体积而使计算终止，并且炸药爆轰形成气体产物飞散过程也很难模拟。为了能模拟大面积金属板材的爆炸焊接整个过程并获得合理的技术工艺参数，采用物质点法进行三维数值模拟分析。物质点法作为一种无网格法，在模拟冲击动力学问题中主要采用显式积分算法。通过将拉格朗日质点单元与固定的欧拉背景网格相结合，可以实现爆炸焊接的复板与基板的高速碰撞、炸药滑移爆轰、金属板面的塑性变形过程的数值模拟，并给出爆炸复合板材的形变、有效塑性应变和复板与基板的碰撞速度的计算结果。采用物质点法模拟的复合板材变形与爆炸焊接实验结果基本一致。计算复板与基板的碰撞速度这个重要的物理参数时，物质点法与Richter理论公式的相对误差不超过13%。数值计算和实验结果表明，物质点法在数值精度和计算效率方面具有优势，物质点法是研究金属焊接爆炸问题的一种有效数值方法。

Simulation and analysis of explosive welding of large-area 304L/Q235B metal plates by material point method

The explosive welding process of large-area metal plates 304L/Q235B involves explosive detonation, high-speed collision and plastic deformation of two metal plates, etc. If the finite element method is used to simulate this problem, twist or distortion of the elements will lead to a decrease in the calculation accuracy, even negative volume elements will appear, resulting in the termination of the calculation. Moreover, it is difficult to use the finite element method to calculate and simulate the dispersion process of the gas products formed by explosive detonation. In order to simulate the whole process of explosive welding of large-area metal plates and obtain reasonable technical parameters, the material point method is used for three-dimensional numerical simulation analysis. As one of the meshless methods, the material point method mainly uses the explicit integral algorithm in the simulation of impact dynamics problems. By combining the Lagrangian particle elements with the fixed Euler background grid, this method can realize numerical simulations of the high-speed collision of clad and base plates, the explosive sliding detonation and the plastic deformation process of the metal plate surface, and obtain the results of deformation, effective plastic strain and collision velocity between the clad plate and the base plate. The deformation of the composite plate simulated by material point method is basically consistent with the experimental results of explosive welding. The collision velocity between the clad plate and the base plate is an important physical parameter. The relative error between the results of the material point method and Richter formula is less than 13%. Based on the numerical calculation by the material point method and the experimental results, it is shown that the material point method has advantages in numerical accuracy and computational efficiency, and it is also verified that the material point method is an effective numerical method to study metal explosive welding.