摘要
大型复杂结构承载后普遍存在局部高应力区,特别是某些巨型结构,由于受几何尺寸和制造能力的限制,其局部高应力往往会接近甚至超过材料的屈服极限,因而成为弹性范围内的设计难题。应用安定性分析设计准则,则可通过利用材料的塑性承载能力很好地解决这类问题。为此,在大型复杂结构的强度分析中引入安定性理论,应用Melan安定下限定理,通过将峰值载荷下的弹塑性应力场与弹性参考应力场相减,构造定理要求的自平衡应力场,并推导了相应的安定性判定条件。在此基础上,结合弹塑性增量有限元技术,通过不同载荷水平下的加载卸载计算,计算相应载荷水平下的残余应力场。根据加载卸载得到的残余应力场与构造的自平衡场的关系,按照安定性判定条件确定安定极限载荷,从而建立了一种适合于大型复杂结构安定性数值分析的新方法,并应用该方法对某125MN锻造液压机的主液压缸缸体结构进行了安定性分析。
The local high stresses appeared commonly in a loaded huge complex structure. Some of them were usually close to or even exceed the material yield strength due to the restrictions of the geo- metric size and the practical manufacture. It was troublesome with the applications of the conventional elastic strength design rule. The elastic-plastic shakedown design rule might utilize the plastic bearing capacity of material, then to solve this kind of strength problem well. Thus the shakedown theorem was introduced, and based on Melan shakedown theorem, a self-equilibrium stress field was constructed by subtractting the elastic-plastic stress field and the elastic reference stress field of the peak load, and the corresponding shakedown condition was derived. Then with the applications of the elasticplastic incremental finite element technique, the loading-unloading calculations for different load levels were conducted to obtain the residual stress fields. Taking consideration of the relation between the residual stress field and the constructed self-equilibrium stress field, the shakedown limit load was determined by the shakedown conditions. Then a shakedown numerical analysis method for huge complex structure was established. The shakedown analysis for the main hydraulic cylinder of a 125 MN forging hydraulic press was performed by this new method.
出处
《中国机械工程》
EI
CAS
CSCD
北大核心
2016年第3期355-360,共6页
China Mechanical Engineering
基金
国家科技重大专项(2013ZX04003031)
国家自然科学基金资助项目(51475408)
河北省高校创新团队领军人才培育计划资助项目(LJRC012)
河北省自然科学基金资助项目(E2015203223)
关键词
弹塑性
安定性
液压缸
安定极限载荷
局部高应力
elastic-plastic
shakedown
hydraulic cylinder body
shakedown limit load
local high stress
