Theeffectsofstrainrateonthedynamicresponseandabnormalbehavior ofsteelbeamsunderpulseloading
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摘要: 为了讨论率敏感材料软钢钢梁受矩形脉冲载荷作用下的动力响应问题,通过直接离散有限变形弹 塑性连续体最小加速度原理中的Lee泛函得到基本控制方程,并将包含应变率的Cowper-Symonds方程嵌入 应力-应变关系方程,使该计算模型计及材料的应变率效应,因而能够准确描述钢梁受爆炸和冲击载荷作用下 的动力响应问题。该计算模型的有效性通过与通用有限元程序ABAQUS比较而得到了验证,并进一步与已 有的刚塑性解做了对比。利用该计算模型进行数值计算,分析了均布和集中脉冲载荷作用下钢梁动力响应的 应变率效应,结果发现对于钢梁存在新的异常行为响应模式,应变率导致异常区域偏移和扩大,已有的刚塑性 解在一定载荷强度范围内不能准确预报钢梁的实际位移。Abstract: Inordertobetterunderstandthedynamicbehaviorofratesensitivematerialandstructure, acomputationalmodelforthedynamicresponseanalysisofamildsteelbeamsubjectedtosquare pulseloadingispresented,whichisderivedthroughdiscretizingdirectlytheLeefunctionaltobeappliedintheminimumprincipleofaccelerationofelastic- plasticcontinuaatfinitedeformation.Since thestrainratedependentCowper-Symondsequationisintegratedintostress-strainrelationequations, theeffectsofstrainratecouldbetakenintoaccount,andthedynamicresponseofsteelbeamunder explosionandimpactloadcouldbepredictedaccurately.Thevalidityofthemodelisverifiedbysimulatedresultsfromthegeneral- purposefiniteelementprogram ABAQUSandfurthercomparedwith therigid-plasticsolutions.Basedonnumericalsimulationofthismodel,theeffectofstrainrateon dynamicresponseofsteelbeamunderuniformlydistributingandconcentratepulseloadsisdiscussed indetail.Thenumericalresultsshowthatthereisanovelresponsemodeofabnormalbehaviorofthe steelbeams,theabnormalwindowisshiftedandenlarged,andtheactualpermanentdeflectionof steelbeamcannotbepredictedbypreviousrigid-plasticmodelincertainrangeofloadmagnitude.
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Key words:
- solidmechanics /
- abnormalbehavior /
- minimumprincipleofacceleration /
- steelbeam /
- novelresponsemode /
- strainrate
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