冲击荷载作用下混凝土结构破坏过程的近场动力学模拟

混凝土在冲击、侵彻等动载荷作用下产生损伤和破坏的过程,其实质是力学模型从连续体到非连续体的转变过程。传统的连续介质理论基于连续性假设并运用偏微分方程求解问题,难以直接用于计算和模拟材料及结构发生破坏的整个过程。近场动力学(Peridynamics,PD)是一种新兴的基于非局部模型描述材料特性的数值计算方法。该方法假定位于连续体内的粒子通过有限的距离与其它粒子相互作用,通过积分计算在一定近场范围(horizon)内具有一定影响域的材料点之间的相互作用力,而不论位移场的连续与否,避免了传统的局部微分方程求解在面临不连续问题时的奇异性和现有多尺度算法的复杂性。该文概述了PD方法的理论基础,描述了其建模思路及计算体系,给出了用近场动力学方法模拟结构受冲击荷载的计算格式。算例结果表明:PD方法可以很好地刻画和模拟材料及结构的损伤累积与渐进破坏过程。最后讨论了PD方法在理论、计算和应用等方面有待进一步研究的问题。

PERIDYNAMICS MODELING OF FAILURE PROCESS OF CONCRETE STRUCTURE SUBJECTED TO IMPACT LOADING

The damage and destruction process of concrete under a shock and a penetration is virtually the process of a mechanical model transformed from a continuum to a discontinuity.The classic continuum mechanics starts with an assumption of a spatially continuous and differentiable displacement field and solve the problem with partial differential equations.It is difficult to compute or model the whole process of the material and structure when suffering damage.Peridynamics(PD) is a continuum theory that employs a nonlocal model to describe material properties.The theory assumes that particles in a continuum interact with each other across a finite distance,formulates problems in terms of integral equations rather than partial differential equations.In this paper,we introduce the theoretical and numerical system of PD and its modeling method.We also introduce the numerical method of structures when subjected to impact loading.The result of the example clarifies the unique advantage of modeling damage accumulation and progressive failure of concrete based on Peridynamics Theory.Finally,some open problems and future research trends in PD are discussed.