Adopting the classical theory of hydrocodes,the constitutive relations of concretes are separated into an equation of state(EoS)which describes the volumetric behavior of concrete material and a strength model which d...Adopting the classical theory of hydrocodes,the constitutive relations of concretes are separated into an equation of state(EoS)which describes the volumetric behavior of concrete material and a strength model which depicts the shear properties of concrete.The experiments on the EoS of concrete is always challenging due to the technical difficulties and equipment limitations,especially for the specimen size effect on the EoS.Although some researchers investigate the shock properties of concretes by fly-plate impact tests,the specimens used in their tests are usually in one size.In this paper,the fly-plate impact tests on concrete specimens with different sizes are performed to investigate the size effect on the shock properties of concrete materials.The mechanical background of the size effect on the shock properties are revealed,which is related to the lateral rarefaction effect and the deviatoric stress produced in the specimen.According to the tests results,the modified EoS considering the size effect on the shock properties of concrete are proposed,which the bulk modulus of concrete is unpredicted by up to 20% if size effects are not accounted for.展开更多
基金supported by the National Natural Science Foundation of China[Grant Nos.51938011 and 51908405]Australian Research Council。
文摘Adopting the classical theory of hydrocodes,the constitutive relations of concretes are separated into an equation of state(EoS)which describes the volumetric behavior of concrete material and a strength model which depicts the shear properties of concrete.The experiments on the EoS of concrete is always challenging due to the technical difficulties and equipment limitations,especially for the specimen size effect on the EoS.Although some researchers investigate the shock properties of concretes by fly-plate impact tests,the specimens used in their tests are usually in one size.In this paper,the fly-plate impact tests on concrete specimens with different sizes are performed to investigate the size effect on the shock properties of concrete materials.The mechanical background of the size effect on the shock properties are revealed,which is related to the lateral rarefaction effect and the deviatoric stress produced in the specimen.According to the tests results,the modified EoS considering the size effect on the shock properties of concrete are proposed,which the bulk modulus of concrete is unpredicted by up to 20% if size effects are not accounted for.
文摘以偶氮二甲酰胺（AC发泡剂）、Zn O和Na HCO3复合体系作为发泡剂,采用模压发泡的方法制备高填充粉煤灰聚氯乙烯（PVC）复合发泡板材,确定复合发泡剂的最优配比及其在复合发泡板材中的最佳用量,并对其性能进行了研究。采用发气量测定、热重/差示扫描量热（TG/DSC）分析对AC发泡剂进行了改性研究,选出分解温度满足加工条件的复合发泡剂。添加不同份数的复合发泡剂制备PVC复合发泡板材,用扫描电子显微镜（SEM）分析其断面,测试板材的冲击强度及弯曲强度。实验结果表明,当AC发泡剂、Zn O和Na HCO3的配比为2∶1∶1.5时,最大发气量为213 m L/g,分解温度区间为165~177℃,满足PVC发泡板材加工。当复合发泡剂添加量为6份时,力学性能达到最佳,弯曲强度为17.63 MPa,冲击强度为21.88 k J/m2,达到国家硬质聚氯乙烯低发泡板材的标准;粉煤灰填充量高达61.16%。
