High frequency shock load is often generated during pyrotechnic device working, which is detrimental to spacecraft structures and electric devices. Therefore, it is valuable to reduce the shock load in pyrotechnic dev...High frequency shock load is often generated during pyrotechnic device working, which is detrimental to spacecraft structures and electric devices. Therefore, it is valuable to reduce the shock load in pyrotechnic device design. Actually, there are several ways to decrease pyroshock loads, such as reduction of powder,installation of buffering structure, insulation of damageable devices, and so on. Considered assuring the function of pyrotechnic device and minimum of structure modification, shock absorbing structure is more propitious to be introduced in pyrotechnic device. In this paper, based on the method of thinwalled metal tube diameter-expanding, a thin-walled tube shock buffering structure was designed on a separate bolt. Built on the simplified structure of a separate bolt, the model of cone piston impacting thin-walled tube absorber was established, and the thin-walled tube shock absorbing characteristics and the relation between cone angles and absorber performance were analyzed. The results showed that the change of buffering force of thin-walled tube could be divided into four phases, and each phase was correspondent to the cone piston structure. In addition, as the cone angle increases, the max shock acceleration changes in the style of decrease-increase-decrease-increase, which is the result of coupled effects of cone piston max enter depth, buffering force and energy loss. In short, these results could establish the relationships between thin-walled tube absorbing performance and its structure, which is of significance to develop low-shock pyrotechnic device.展开更多
A dynamical moving pressure structural numerical calculation model using the internal ballistics calculation pressure-time results was constituted and the vicinity of the internal ballistics and quasiinternal ballisti...A dynamical moving pressure structural numerical calculation model using the internal ballistics calculation pressure-time results was constituted and the vicinity of the internal ballistics and quasiinternal ballistics structural model was checked. The Von Mises stresses obtained by the dynamical structural numerical model calculations and the Von Mises stresses calculated from the shot test strain measurements were compared. The difference for the worse case was 20% and for the best case was 0.1%.Furthermore, the model gave better agreement for the higher charge masses. The numerical structural quasi-internal ballistics computation model created was verified for the top charge mass which represents the highest stress condition and used in a gun barrel design.展开更多
Being aimed at the inside wall wrinkling and sinking phenomenon of palladium-yttrium alloy thin wall spiral tube used for preparation of high purity hydrogen, extraction of hydrogen isotope, and purification and separ...Being aimed at the inside wall wrinkling and sinking phenomenon of palladium-yttrium alloy thin wall spiral tube used for preparation of high purity hydrogen, extraction of hydrogen isotope, and purification and separation of hydrogen in the winding process, this article analyzed the reasons for above phenomena, established a numerical simulation model of winding process of above tube, using elastic-plastic Finite Element method analyzed the max. tensile stress and max. compression stress and their locations, thereby provides a theory base for the control of working forming course of thin wall spiral tube.展开更多
Today, improving the weight/load carrying capacity ratio of a part is the matter of studies in most of the scientific and industrial areas.Autofrettage dimensions, the amount of material removed from outer and inner r...Today, improving the weight/load carrying capacity ratio of a part is the matter of studies in most of the scientific and industrial areas.Autofrettage dimensions, the amount of material removed from outer and inner radius while manufacturing and the service pressure applied affect the residual stress distribution throughout the wall thickness and hence the load-bearing capacity of a thick-walled cylinder. Calculation of residual stresses after autofrettage process and optimization of autofrettage outline dimensions by using the amount of service pressures applied are common issues in literature.In this study, mandrel-cylinder tube interference dimensions were renovated by using traditional methods for swage autofrettage process of a gun barrel. Also, the residual stresses in the cylinder after autofrettage process, inside and outside material removal process and the variable service pressure throughout the cylinder applied were taken into consideration and incorporated into the design. By using the constrained optimization method, wall thickness(thus the weight) was optimized(minimized)to achieve the specified safety factor along the length of the cylinder. For the same cylinder, the results of the suggested analytical/with residual stress calculation approach were compared to analytical/without residual stress calculation results and numerical topology optimization method calculation results. Since the experimental measurement results are not yet available, it was not possible to compare them with the calculation results.The suggested approach enabled 22.9% extra weight reduction in proportion to numerical topology optimization and enabled 4.2% extra weight reduction in proportion to analytical/without residual stress optimization.Using this approach, the gain from residual stresses after autofrettage operation, the loss of residual stresses after material removal, and the effects of service pressures can be taken into account for each stage of design.展开更多
深度调峰背景下,对火电机组的灵活性要求越来越高。锅炉低负荷运行下存在燃烧火焰偏斜、管内工质分配不均以及受热面超温爆管等问题。为保证火电机组安全、稳定、灵活的运行,有必要对锅炉水冷壁参数分布进行详细研究。该文建立锅炉耦合...深度调峰背景下,对火电机组的灵活性要求越来越高。锅炉低负荷运行下存在燃烧火焰偏斜、管内工质分配不均以及受热面超温爆管等问题。为保证火电机组安全、稳定、灵活的运行,有必要对锅炉水冷壁参数分布进行详细研究。该文建立锅炉耦合模型,包括燃烧侧模型、工质侧模型和受热面壁温计算模型,可实现锅炉燃烧侧和工质侧以及受热面壁温的耦合计算。基于Fluent平台开展锅炉燃烧侧流动、燃烧和传热等过程以及受热面壁面温度的计算,采用用户自定义函数(user defined function,UDF)开展工质侧流动和传热过程计算,两者以受热面为边界进行数据交互与更新迭代。基于该模型对某1000 MW双切圆锅炉进行研究,结果表明:1)炉膛出口氧量和飞灰含碳量模拟值分别为2.53%和2.61%,水冷壁出口工质温度为744.59 K,模拟结果与现场实际测量值一致性较好;2)采用耦合模型探究水冷壁的热流密度、工质温度、传热系数以及管壁温度详细分布。研究结果有利于为锅炉故障诊断和运行优化提供更加准确的参考信息。展开更多
文摘High frequency shock load is often generated during pyrotechnic device working, which is detrimental to spacecraft structures and electric devices. Therefore, it is valuable to reduce the shock load in pyrotechnic device design. Actually, there are several ways to decrease pyroshock loads, such as reduction of powder,installation of buffering structure, insulation of damageable devices, and so on. Considered assuring the function of pyrotechnic device and minimum of structure modification, shock absorbing structure is more propitious to be introduced in pyrotechnic device. In this paper, based on the method of thinwalled metal tube diameter-expanding, a thin-walled tube shock buffering structure was designed on a separate bolt. Built on the simplified structure of a separate bolt, the model of cone piston impacting thin-walled tube absorber was established, and the thin-walled tube shock absorbing characteristics and the relation between cone angles and absorber performance were analyzed. The results showed that the change of buffering force of thin-walled tube could be divided into four phases, and each phase was correspondent to the cone piston structure. In addition, as the cone angle increases, the max shock acceleration changes in the style of decrease-increase-decrease-increase, which is the result of coupled effects of cone piston max enter depth, buffering force and energy loss. In short, these results could establish the relationships between thin-walled tube absorbing performance and its structure, which is of significance to develop low-shock pyrotechnic device.
基金Ministry of Science, Industry, and Technology which supported this project under the Industrial Thesis Support Program
文摘A dynamical moving pressure structural numerical calculation model using the internal ballistics calculation pressure-time results was constituted and the vicinity of the internal ballistics and quasiinternal ballistics structural model was checked. The Von Mises stresses obtained by the dynamical structural numerical model calculations and the Von Mises stresses calculated from the shot test strain measurements were compared. The difference for the worse case was 20% and for the best case was 0.1%.Furthermore, the model gave better agreement for the higher charge masses. The numerical structural quasi-internal ballistics computation model created was verified for the top charge mass which represents the highest stress condition and used in a gun barrel design.
文摘Being aimed at the inside wall wrinkling and sinking phenomenon of palladium-yttrium alloy thin wall spiral tube used for preparation of high purity hydrogen, extraction of hydrogen isotope, and purification and separation of hydrogen in the winding process, this article analyzed the reasons for above phenomena, established a numerical simulation model of winding process of above tube, using elastic-plastic Finite Element method analyzed the max. tensile stress and max. compression stress and their locations, thereby provides a theory base for the control of working forming course of thin wall spiral tube.
基金Ministry of Science, Industry, and Technology which supported the project under the Industrial Thesis Support Program
文摘Today, improving the weight/load carrying capacity ratio of a part is the matter of studies in most of the scientific and industrial areas.Autofrettage dimensions, the amount of material removed from outer and inner radius while manufacturing and the service pressure applied affect the residual stress distribution throughout the wall thickness and hence the load-bearing capacity of a thick-walled cylinder. Calculation of residual stresses after autofrettage process and optimization of autofrettage outline dimensions by using the amount of service pressures applied are common issues in literature.In this study, mandrel-cylinder tube interference dimensions were renovated by using traditional methods for swage autofrettage process of a gun barrel. Also, the residual stresses in the cylinder after autofrettage process, inside and outside material removal process and the variable service pressure throughout the cylinder applied were taken into consideration and incorporated into the design. By using the constrained optimization method, wall thickness(thus the weight) was optimized(minimized)to achieve the specified safety factor along the length of the cylinder. For the same cylinder, the results of the suggested analytical/with residual stress calculation approach were compared to analytical/without residual stress calculation results and numerical topology optimization method calculation results. Since the experimental measurement results are not yet available, it was not possible to compare them with the calculation results.The suggested approach enabled 22.9% extra weight reduction in proportion to numerical topology optimization and enabled 4.2% extra weight reduction in proportion to analytical/without residual stress optimization.Using this approach, the gain from residual stresses after autofrettage operation, the loss of residual stresses after material removal, and the effects of service pressures can be taken into account for each stage of design.
文摘深度调峰背景下,对火电机组的灵活性要求越来越高。锅炉低负荷运行下存在燃烧火焰偏斜、管内工质分配不均以及受热面超温爆管等问题。为保证火电机组安全、稳定、灵活的运行,有必要对锅炉水冷壁参数分布进行详细研究。该文建立锅炉耦合模型,包括燃烧侧模型、工质侧模型和受热面壁温计算模型,可实现锅炉燃烧侧和工质侧以及受热面壁温的耦合计算。基于Fluent平台开展锅炉燃烧侧流动、燃烧和传热等过程以及受热面壁面温度的计算,采用用户自定义函数(user defined function,UDF)开展工质侧流动和传热过程计算,两者以受热面为边界进行数据交互与更新迭代。基于该模型对某1000 MW双切圆锅炉进行研究,结果表明:1)炉膛出口氧量和飞灰含碳量模拟值分别为2.53%和2.61%,水冷壁出口工质温度为744.59 K,模拟结果与现场实际测量值一致性较好;2)采用耦合模型探究水冷壁的热流密度、工质温度、传热系数以及管壁温度详细分布。研究结果有利于为锅炉故障诊断和运行优化提供更加准确的参考信息。
