机床结构结合面静态特性研究与内聚力模拟

STATIC CHARACTERISTICS AND COHESIVE ZONE MODEL OF JOINT SURFACES IN MACHINE TOOLS

针对机床结构中的平面结合面,通过实验分析了结合面在均布面压作用下的结合面法向变形与平均压力的关系;将结合面表面简化为半圆弧和正弦曲线两种微观形貌,利用有限元方法模拟结合面的接触变形力学行为,计算结果显示半圆弧形貌接触分析结果与实验结果较为接近.从结合面作用的物理本质出发,将结合面的相互作用等效为内聚力效应,利用内聚力模型分析了结合面的静态力学行为;内聚力模型计算结果与实验结果吻合较好.

To satisfy the functional,process and design requirements,each type of machine tool is assembled by various parts or components at certain order instead of a complete and continuous structure,and hence a variety of joint surfaces exist between different parts or components.As the joint surfaces are discrete surfaces,their stiffness and damping affect considerably the static and dynamic performance of the machine tool.In the present paper,model experiments were firstly carried out to characterize the relationship between contact pressure and deformation of nominally plain joint surfaces.The contact behavior of the joint was then simulated using the method of finite elements by simplifying the measured morphology of the joint surfaces as semi-circular or sinusoidal.It was demonstrated that the numerical simulations agreed better with the experimental measurements if the joint surface morphology was taken as semi-circular.Finally,by assuming that the interaction between a pair of joint surfaces is equivalent to cohesion effects,the classical cohesive zone model（CZM） was adopted to analyze the mechanical behavior of the joint.It was established that the model predictions agree well with the experimental results.