The light weight heat treated B-grade bulletproof steel was developed through composition design and optimization based on multiplex alloying,multiplex micro-alloying design ideas and complex phase structure strengthe...The light weight heat treated B-grade bulletproof steel was developed through composition design and optimization based on multiplex alloying,multiplex micro-alloying design ideas and complex phase structure strengthening theory.The puzzle how to avoid the quenching deformation problem of super high strength thin sheet was solved through heat treatment in a die with a set of cooling system.Such B-grade bulletproof steel plate has fine tempered lath martensite structure.The shooting and certification test results showed that the shoot resistance of B-grade bulletproof steel plate can meet the protection demand of Protection specification for cash carrying vehicles(GA 164—2005).In comparison with B-grade bulletproof steel plate made by one of the companies in Sweden,the weight of the developed B-grade bulletproof steel plate can be decreased by 8 %under the same shoot resistance condition.It will be meaningful for cash truck and anti-hijacking vehicle to realize light weight,energy conservation and emission reduction.展开更多
Rutting is a chronic disease in asphalt pavements despite several mitigation measures. Although many attempts have been made by both researchers and practitioners to develop rutting prediction models, each model, howe...Rutting is a chronic disease in asphalt pavements despite several mitigation measures. Although many attempts have been made by both researchers and practitioners to develop rutting prediction models, each model, however, has certain inherent limitations due to assumptions and data used during the development of the model. Placement of an asphalt overlay is the most common method used in Zambia to rehabilitate existing asphalt pavements. The objective of this research is to go towards developing a national rutting prediction model for use in tropical hot climates based on default finite element creep and elasto-visco-plastic analysis tools in ABAQUS. Dynamic modulus and repeated load tests are conducted on overlay mixtures designed based on the pavement residual structural adequacy from deflection tests to provide material properties for the constitutive rutting model. Unified, three dimensional linear viscoelastic boundary value problems were formulated for each five national representative pavement sections. In general, the FE （finite element） creep and elasto-visco-plastie rutting evolutions were in agreement with the measured laboratory scaled one third mobile load simulators. Performance ranking of the validated models revealed optimal pavement system combination suitable for calibration. The study recommends future directions for local adoption of the South African mechanistic-empirical design method currently being developed.展开更多
文摘The light weight heat treated B-grade bulletproof steel was developed through composition design and optimization based on multiplex alloying,multiplex micro-alloying design ideas and complex phase structure strengthening theory.The puzzle how to avoid the quenching deformation problem of super high strength thin sheet was solved through heat treatment in a die with a set of cooling system.Such B-grade bulletproof steel plate has fine tempered lath martensite structure.The shooting and certification test results showed that the shoot resistance of B-grade bulletproof steel plate can meet the protection demand of Protection specification for cash carrying vehicles(GA 164—2005).In comparison with B-grade bulletproof steel plate made by one of the companies in Sweden,the weight of the developed B-grade bulletproof steel plate can be decreased by 8 %under the same shoot resistance condition.It will be meaningful for cash truck and anti-hijacking vehicle to realize light weight,energy conservation and emission reduction.
文摘Rutting is a chronic disease in asphalt pavements despite several mitigation measures. Although many attempts have been made by both researchers and practitioners to develop rutting prediction models, each model, however, has certain inherent limitations due to assumptions and data used during the development of the model. Placement of an asphalt overlay is the most common method used in Zambia to rehabilitate existing asphalt pavements. The objective of this research is to go towards developing a national rutting prediction model for use in tropical hot climates based on default finite element creep and elasto-visco-plastic analysis tools in ABAQUS. Dynamic modulus and repeated load tests are conducted on overlay mixtures designed based on the pavement residual structural adequacy from deflection tests to provide material properties for the constitutive rutting model. Unified, three dimensional linear viscoelastic boundary value problems were formulated for each five national representative pavement sections. In general, the FE （finite element） creep and elasto-visco-plastie rutting evolutions were in agreement with the measured laboratory scaled one third mobile load simulators. Performance ranking of the validated models revealed optimal pavement system combination suitable for calibration. The study recommends future directions for local adoption of the South African mechanistic-empirical design method currently being developed.
