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本文主要研究柴油机过渡工况下气缸盖非稳定热负荷的测试技术,以便为有限元计算非稳定温度场和准稳态热应力场提供真实、可信的边界条件;为判断和评价气缸盖可靠性,为气缸盖及其他受热零部件的疲劳寿命提供实机温度、应力测试依据。试验是在一台S195型柴油机上进行的。本文着重考察最恶劣而又典型的起动和停机工况。在对发动机零部件无损条件下,用高温电阻应变片和露头型铠装热电偶测取该机气缸盖的温度历程,并在材料应力发生最大变化的区域中测取最危险点上的应变曲线。由应变实测历程发现柴油机受热零部件在突加工况下将出现应力峰值。文中所提出的方法,可满足柴油机设计、生产及使用部门的需要。由实测的温度扬可反求气缸内传热第三类边界条件,它比较真实地反映气缸盖所处复杂环境中的边界条件,与实测值能较好的吻合,从而为非稳定热负荷的理论计算提供了可靠的保证。
In this paper, we mainly study the testing technology of unsteady thermal load of cylinder head under transient condition of diesel engine, in order to provide true and credible boundary conditions for the finite element calculation of unsteady temperature field and quasi-steady state thermal stress field. In order to judge and evaluate the reliability of cylinder head For the cylinder head and other parts of the fatigue life fatigue to provide real machine temperature, stress test basis. The test was carried out on a S195 diesel engine. This article focuses on the worst and typical start and stop conditions. Under the condition of non-destructive parts of the engine, the temperature history of the cylinder head of the machine is measured with a high-temperature resistance strain gauge and outcropped armored thermocouple and the strain curve at the most dangerous point is measured in the area where the stress of the material changes most greatly . From the measured strain history found diesel engine heating parts in sudden conditions will appear stress peaks. The proposed method to meet the diesel engine design, production and use of the department’s needs. From the measured temperature, Yang can reverse the third type of boundary conditions in the cylinder heat transfer, which more truly reflect the cylinder head in the complex environment of the boundary conditions, and the measured values can be better consistent, so as to non-stable thermal load Theoretical calculations provide a reliable guarantee.