发动机复层气门座接触特性研究

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采用Ansys／Ls-dyna平台，基于动态接触理论建立发动机气门一气门座冲击接触仿真分析模型，探讨发动机复层气门座材料匹配性对其接触特性的影响。研究结果表明：复层气门座摩擦副匹配对其接触应力影响较大，特别是反映材料弹性特征的模量E和密度P。当弹性模量匹配比Ec／Eq小于0．5时，等效应力σN随Ec／Eq。的增大而增大，但当Ec／Eq大于0．5以后，σN的变化速率显得较平缓；密度匹配比ρc／ρq对σN的影响规律与E相似，其中σN随ρc／ρq变化速率的改变大约发生在0．5，当ρc／ρq超过0．5时，σN的变化速率也呈现平缓趋势。复层厚度h对σN的影响也较大，且存在非线性现象。一般地，h的增加可缓冲冲击接触，使σN降低，但当h达到0．6mm时，σN显现反弹上升的现象，且其增幅与复层材料特性有关，并且h较小时，气门的反弹较小，接触应力较平缓。 Based on dynamic contact theory and Ansys/ls-dyna platform, a simulating model to analyze the impact contact characteristics of the multiple layer valve seat of engine was established, and used to discuss the effects of both material characteristics and layer thickness on the impact contact stress and time. The results show that the influence of material match on impact contact stress is great,especially the modulus of elasticity E and density p. When elastic modulus match ratio Ec/Eq is less than 0. 5, effective stress o＇N increase with the Ec/Eq, but when more than 0. 5, the increase rate appears more gentle, the effects of the density match ratio ρc/ρq on the σN is similar to Ec/Eq, when the pc/pq is more than 0. 5, the σN increase rate with ρc/ρqis also very slow. Multiple layer thickness h has the larger influence on theσN, and presents a nonlinear phenomenon. Generally, the increase of h can buffer impact contact and make σN low, but when h reduces to 0. 6 mm,σN appears a increasing rebound phenomenon,the increasing rate depends on the material characteristics of multiple layer, when h is small, the bounce of the valve is smaller and σN becomes also gentle.