静不定结构的热应力分析

分析了受约束机构内材料热应力存在的危害,给出静不定结构内热应力的定量描述方式:弹性变形状态时,热应力仅与线膨胀系数、弹性模量及温度变量成正比关系;当热应力达到材料在某温度下的屈服强度时,其热膨胀发生弹塑性转变,热应力为当时温度下的屈服强度。采用热模拟试验机测试了材料的温度与热应力关系,分析结果与数值模型基本吻合,测出刚性约束下45钢在升温至620℃时热应力等于其屈服强度约200 MPa。

Analysis of thermal stress on statically indeterminate mechanism

The harmfulness of thermal stress on mechanism was analyzed,and a quantitative evaluation model of the effect of the thermal stress was derived.Under elastic situation,the thermal stress was directly proportional to the linear expansion coefficient,elastic modulus,and temperature variable.When the thermal stress reached the yield strength of the material at a certain temperature,its thermal expansion experienced an elastic-plastic transformation,and the thermal stress was the yield strength at the temperature.Then,the relation between temperature and thermal stress was analyzed by a thermal simulation test machine Gleeble 1500.Results of the experiment were in accordance with the theoretical prediction,and the thermal stress of steel 45 under full restraint at 620℃reached its yield strength of about 200 MPa.