As the variable stiffness of testing specimen affects load stiffness , the theoretical analysis and simulation study of the effect of variable load stiffness on the system are done . the degree and tendency of the effect of variable load stiffness on the control quality and accuracy are given , furthermore , a new extension control algorithm for material testing machine is presented in this thesis . by these algorithm , the problem existed and confused in testing machine engineering in a long term can be solved completely 針對試樣剛度變化對負載剛度的影響問題,進行了負載剛度變化對控制系統(tǒng)影響的理論分析和仿真研究,從理論上分析了材料拉伸試樣進入屈服階段時試驗過程產(chǎn)生震蕩的原因,并研究開發(fā)了相應的可拓智能控制策略的解決辦法,解決了國內(nèi)外材料試驗機工程界長期未解決的問題。