Impact damage tolerance is provided in intensity design on composites. The compression intensity of impacted composites requires more than 60% of its original intensity. The influence of impact on compressive intensit...Impact damage tolerance is provided in intensity design on composites. The compression intensity of impacted composites requires more than 60% of its original intensity. The influence of impact on compressive intensity and electrical resistance of carbon fabric/epoxy-matrix composites was studied in this paper. The experimental results shows that impact can cause damage in composites, degenerate compressive intensity, and increase resistance. The electrical resistance change rate was used as an evaluation indicator of impact damage tolerance of composites. Impact damage, which results from the applying process of composites, can be identified in time by electrical resistance measurement. So, the safety performance of composites can also be improved.展开更多
With the continuous advancement of China’s infrastructure construction to the west,according to the geographic situation in the southwest region,such as mountainous areas and complex terrain,the road construction pro...With the continuous advancement of China’s infrastructure construction to the west,according to the geographic situation in the southwest region,such as mountainous areas and complex terrain,the road construction process is inevitably accompanied by earth and rock blasting.To improve the quality and safety of the project,this paper addresses the problems of land and rock blasting faced in the construction of mountain road projects,taking the research of rock dynamic mechanics test as the starting point,and using a combination of theoretical analysis and experimental research methods.The specific research content includes the following parts:dynamic impact compression test(SHPB),dynamic splitting tensile test,and stress-strain curve analysis of the test results,which provides the theoretical basis and numerical parameters for the numerical simulation of future engineering blasting.展开更多
High-performance bismaleimdes (BMI) matrix composites reinforced by graphite fibers were prepared and toughened with a thermoplastic component (PAEK) by using the Ex-situ concept. Experimental matrix was designed for ...High-performance bismaleimdes (BMI) matrix composites reinforced by graphite fibers were prepared and toughened with a thermoplastic component (PAEK) by using the Ex-situ concept. Experimental matrix was designed for overall toughening of the base resin, periodically interleaving thermoplastic films into each plies (Ex-situ concept) and for varying the film compositions. The highest impact damage resistance characterized by compression after impact (CAI) was obtained for the laminates toughened on the Ex-situ concept, especially, when two-component cast films of a special ration of PAEK/BMI 60∶40 were interleaved though the thermoplastic concentration for the overall toughening, interleaving the pure thermoplastic films and the two-component films was comparable. There were two peaks found in the DSC trace of the laminates toughened implying a phase separation process occurred. The glass transition temperature of the laminates toughened was slightly reduced due to the low-temperature PAEK. Morphological study revealed a typical granular structure just in the interplay region as a result of spinodal decomposition and coarsening process. This was in agreement of the result of DSC investigation.展开更多
This paper seeks to deal with progressive damage behaviors of woven composite laminates subjected to low-velocity impact(LVI),tension-after-impact(TAI)and compression-afterimpact(CAI).The LVI,TAI and CAI tests were co...This paper seeks to deal with progressive damage behaviors of woven composite laminates subjected to low-velocity impact(LVI),tension-after-impact(TAI)and compression-afterimpact(CAI).The LVI,TAI and CAI tests were conducted on woven carbon fibre lamina3238 A/CF3052 and woven glass fibre lamina 3238 A/EW250 F,and the time-dependent LVI contact force and deflection curves,static TAI and CAI load versus displacement curves were determined and discussed.A modified progressive damage model was presented for explicit dynamic LVI and implicit static TAI and CAI analysis by using basic material properties and geometrical dimensions,and progressive damage LVI,TAI and CAI behaviors of woven composite laminates were simulated,demonstrating a good correlation between simulations and experiments.展开更多
The dynamic compressive behavior and constitutive relations of Lanthanum（La） metal was determined by using the first compression in split Hopkinson pressure bar（SHPB） tests at different strain rates and temperatur...The dynamic compressive behavior and constitutive relations of Lanthanum（La） metal was determined by using the first compression in split Hopkinson pressure bar（SHPB） tests at different strain rates and temperatures.The constitutive relation of La metal determined in a certain range of strains was employed and adjusted in numerically simulating large deformations of La metal specimens generated by multi-compression in SHPB tests and recorded by a high-speed camera.The dynamic compressive behavior and constitutive relations of La metal under multiple SHPB tests loading was also revealed.The results of scanning electron microscope（SEM） investigation of the recovered La metal specimens for typical tests showed that there was a variety of deformation microstructures depending on strain rate,temperature and stress state.展开更多
基金Funded by Key Laboratory of Nondestructive Testing (Nanchang Hangkong University)Ministry of Education, China(No. ZD200829001)Department of Education of Jiangxi Province, China(No. GJJ10531)
文摘Impact damage tolerance is provided in intensity design on composites. The compression intensity of impacted composites requires more than 60% of its original intensity. The influence of impact on compressive intensity and electrical resistance of carbon fabric/epoxy-matrix composites was studied in this paper. The experimental results shows that impact can cause damage in composites, degenerate compressive intensity, and increase resistance. The electrical resistance change rate was used as an evaluation indicator of impact damage tolerance of composites. Impact damage, which results from the applying process of composites, can be identified in time by electrical resistance measurement. So, the safety performance of composites can also be improved.
文摘With the continuous advancement of China’s infrastructure construction to the west,according to the geographic situation in the southwest region,such as mountainous areas and complex terrain,the road construction process is inevitably accompanied by earth and rock blasting.To improve the quality and safety of the project,this paper addresses the problems of land and rock blasting faced in the construction of mountain road projects,taking the research of rock dynamic mechanics test as the starting point,and using a combination of theoretical analysis and experimental research methods.The specific research content includes the following parts:dynamic impact compression test(SHPB),dynamic splitting tensile test,and stress-strain curve analysis of the test results,which provides the theoretical basis and numerical parameters for the numerical simulation of future engineering blasting.
文摘High-performance bismaleimdes (BMI) matrix composites reinforced by graphite fibers were prepared and toughened with a thermoplastic component (PAEK) by using the Ex-situ concept. Experimental matrix was designed for overall toughening of the base resin, periodically interleaving thermoplastic films into each plies (Ex-situ concept) and for varying the film compositions. The highest impact damage resistance characterized by compression after impact (CAI) was obtained for the laminates toughened on the Ex-situ concept, especially, when two-component cast films of a special ration of PAEK/BMI 60∶40 were interleaved though the thermoplastic concentration for the overall toughening, interleaving the pure thermoplastic films and the two-component films was comparable. There were two peaks found in the DSC trace of the laminates toughened implying a phase separation process occurred. The glass transition temperature of the laminates toughened was slightly reduced due to the low-temperature PAEK. Morphological study revealed a typical granular structure just in the interplay region as a result of spinodal decomposition and coarsening process. This was in agreement of the result of DSC investigation.
基金the National Natural Science Foundation of China(No.51875021)。
文摘This paper seeks to deal with progressive damage behaviors of woven composite laminates subjected to low-velocity impact(LVI),tension-after-impact(TAI)and compression-afterimpact(CAI).The LVI,TAI and CAI tests were conducted on woven carbon fibre lamina3238 A/CF3052 and woven glass fibre lamina 3238 A/EW250 F,and the time-dependent LVI contact force and deflection curves,static TAI and CAI load versus displacement curves were determined and discussed.A modified progressive damage model was presented for explicit dynamic LVI and implicit static TAI and CAI analysis by using basic material properties and geometrical dimensions,and progressive damage LVI,TAI and CAI behaviors of woven composite laminates were simulated,demonstrating a good correlation between simulations and experiments.
基金supported by National Natural Science Foundation of China (10872100,11072118)Natural Science Foundation of Zhejiang(Y12A020008)
文摘The dynamic compressive behavior and constitutive relations of Lanthanum（La） metal was determined by using the first compression in split Hopkinson pressure bar（SHPB） tests at different strain rates and temperatures.The constitutive relation of La metal determined in a certain range of strains was employed and adjusted in numerically simulating large deformations of La metal specimens generated by multi-compression in SHPB tests and recorded by a high-speed camera.The dynamic compressive behavior and constitutive relations of La metal under multiple SHPB tests loading was also revealed.The results of scanning electron microscope（SEM） investigation of the recovered La metal specimens for typical tests showed that there was a variety of deformation microstructures depending on strain rate,temperature and stress state.
