摘要
通过对不同初始密度铍试样进行单轴压缩试验,研究了多孔铍的宏观屈服特性,并首次给出了多孔铍Shima模型形式的屈服准则。结果表明:应力修正因子(表观应力与基体应力的比值)f’与相对密度R呈幂函数关联,幂指数为2. 8866,系数为1. 0;静水压影响因子f与孔洞率1-R也呈幂函数关联,幂指数为-0. 3862,系数为1/2. 8997;利用本屈服准则对铍热等静压成型的有限元仿真可实现的最高压制相对密度达0. 98;对比计算显示,f’,f的准确性对仿真结果的可靠性影响甚大。结果还表明:由本屈服准则可以获得泊松比v关于R的显性函数,v随R单调增加,计算结果与实测值相符;由v可以确定屈服准则的适用范围,是f≥21/2/3,表达成相对密度,对铍而言R≥0. 5548。进一步分析表明,等静压工艺可以显著降低屈服应力,更容易实现铍的成型和致密化。
Through uniaxial compression tests of beryllium specimens with different initial densities,the macro yield characteristics of porous beryllium was investigated,and the yield criterion of porous beryllium with Shima model form was given first time. The results showed that:the stress modified factor f’(ratio of apparent stress and matrix stress)was associated with the relative density R in the form of power function,with power exponent as 2.8866 and coefficient as 1.0;the power function relationship was also existed between hydrostatic pressure influence factor f and the void ratio 1-R,with power exponent as-0.3862 and coefficient as 1/2.8997;with the yield criterion,the highest relative density achieved from the finite element simulation on hot isostatic pressing of beryllium could be up to 0.98;the comparison of calculations indicated that the accuracy of f’ and f had a great influence on the reliability of simulation. Further results showed that:an explicit function for Poisson ratio v with R could be obtained according to the yield criterion,v increased monotonously with R,the results of the function were in agreement with the measured values;then a boundary of validity of the yield criterion according to v could be determined,it was f ≥ 21/2/3,expressing as relative density,it was R ≥0.5548 for beryllium.Further analyses indicated that,the isostatic pressing process was indeed easier to realize the forming and densification of beryllium,by significantly reducing the yield stress.
作者
马宏昌
何力军
李志年
吕一格
陈磊
张健康
Ma Hongchang;He Lijun;Li Zhinian;Lv Yige;Chen Lei;Zhang Jiankang(Ningxia Key Laboratory of Photovoltaic Materials,Ningxia University,Yinchuan 750021,China;State Key Laboratory of Special Rare Metal Materials,Northwest Rare Metal Materials Research Institute,Shizuishan 753000,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2020年第9期949-956,共8页
Chinese Journal of Rare Metals
基金
稀有金属特种材料国家重点实验室开放课题基金项目(SKL2017K001)
宁夏自然科学基金项目(NX17037)资助。
