Based on the static compression experiments, the compressive stress-strain curve of multi-layer corrugated boards is simplified into three sections of linear elasticity, sub-buckling going with local collapse and dens...Based on the static compression experiments, the compressive stress-strain curve of multi-layer corrugated boards is simplified into three sections of linear elasticity, sub-buckling going with local collapse and densification. By considering the structure factors of multi-layer corrugated boards, the energy absorption model is obtained and characterized by the structure factors of corrugated cell-wall. The model is standardized by the solid modulus and it is universal for corrugated structures of different basis material. In the liner-elastic section, with the increase of the load, the energy absorption per unit volume of multi-layer corrugated boards gradually increases; in the sub-buckling section going with local collapse, the compression resistance of multi-layer corrugated boards goes on under a nearly constant load, but the energy absorption per unit volume rapidly increases with the increase of the compression strain. It is shown as an ascending curve in the energy absorption diagram. In the densification section, the corrugated sandwich core has no energy absorption capability. A good consistency is achieved between theoretical and experimental energy absorption curves. In designing the cushioning package, the cushioning properties can be evaluated by the theoretical model without more experiments. The suggested method to develop the energy absorption diagram for corrugated boards can be used to characterize the cushioning properties and optimize the structures of corrugated sandwich structures.展开更多
The quality of printed circuit board(PCB)micro-hole processing directly determines the stability of the inner and outer circuit connections.Micro-hole drilling technology is a typical method for PCB micro-hole process...The quality of printed circuit board(PCB)micro-hole processing directly determines the stability of the inner and outer circuit connections.Micro-hole drilling technology is a typical method for PCB micro-hole processing.The problem of optimal control of its drilling force is one of the main factors affecting the quality of micro-hole machining.To address this problem,the thrust forces and torques in PCB drilling were first modeled and analyzed,and the corresponding prediction models were established.The drilling force analysis was carried out through the micro-hole drilling experiment,the specific cutting energy under different feed rates was calculated,the influence of the size effect was clarified,and the accuracy of the prediction model was verified.The result shows that during the drilling of glass fiber cloth,changes in the material removal mechanism are induced as the feed per revolution is varied.When the feed per revolution is less than the tool edge radius,the glass fiber is not cut by the main cutting edge,but is crushed and broken.When the feed per revolution is greater than the radius of the tool edge,the glass fiber is cut by the main cutting edge.At the same time,the established analytical model can accurately reflect the influence of the size effect on the drilling torque in PCB micro-hole drilling,and the error is within 10%.This method has certain practical application value in controlling PCB micro hole processing quality.展开更多
针对目前国内一些保温材料虽具有较好的热工性能,但普遍存在吸湿吸潮吸水性大的问题,作者开发了憎水珍珠岩保温板,用于建筑外墙内保温和屋面保温。该板密度:220 kg/m^3,抗压强度:0.6～0.9 MPa,导热系数:<0.065 W/(m·K),憎水率:...针对目前国内一些保温材料虽具有较好的热工性能,但普遍存在吸湿吸潮吸水性大的问题,作者开发了憎水珍珠岩保温板,用于建筑外墙内保温和屋面保温。该板密度:220 kg/m^3,抗压强度:0.6～0.9 MPa,导热系数:<0.065 W/(m·K),憎水率:≥98%。应用实践表明:240 mm 砖墙内贴50 mm 该板,平均传热系数为0.74 W/(m^2·K),满足节能50%的要求;用于屋面保温:60 mm 和80 mm 厚憎水珍珠岩保温板的热工性能分别优于200 mm 和250 mm 厚的加气混凝土块;且降低造价。文章还介绍了该板的生产工艺和施工工艺,并进行了经济、技术分析。展开更多
为解决某车型后立柱外板成形中出现的成形不足、起皱和破裂等问题,采用中心复合试验设计(CCD)和数值模拟相结合的方法,分析成形过程中拉延筋阻力系数和压边力对下部立柱外板成形质量的影响规律。并以成形性能Z_1、流入量Z_2和零件厚薄...为解决某车型后立柱外板成形中出现的成形不足、起皱和破裂等问题,采用中心复合试验设计(CCD)和数值模拟相结合的方法,分析成形过程中拉延筋阻力系数和压边力对下部立柱外板成形质量的影响规律。并以成形性能Z_1、流入量Z_2和零件厚薄均匀性Z_3为优化目标,以拉延筋阻力系数和压边力为优化因素,借助Design-Expert、MATLAB等软件,构建4因素5水平的二阶响应面模型,再采用多目标优化求得最优工艺参数组合:拉延筋X_1=0.60、X_2=0.61、X_3=0.64和压边力F_0=390 k N。实际生产结果表明,采用最优的生产工艺参数组合,可获得厚度均匀、无破裂无起皱的后立柱外板零件。展开更多
基金Funded by the National Natural Science Foundation of China (No.50905120)
文摘Based on the static compression experiments, the compressive stress-strain curve of multi-layer corrugated boards is simplified into three sections of linear elasticity, sub-buckling going with local collapse and densification. By considering the structure factors of multi-layer corrugated boards, the energy absorption model is obtained and characterized by the structure factors of corrugated cell-wall. The model is standardized by the solid modulus and it is universal for corrugated structures of different basis material. In the liner-elastic section, with the increase of the load, the energy absorption per unit volume of multi-layer corrugated boards gradually increases; in the sub-buckling section going with local collapse, the compression resistance of multi-layer corrugated boards goes on under a nearly constant load, but the energy absorption per unit volume rapidly increases with the increase of the compression strain. It is shown as an ascending curve in the energy absorption diagram. In the densification section, the corrugated sandwich core has no energy absorption capability. A good consistency is achieved between theoretical and experimental energy absorption curves. In designing the cushioning package, the cushioning properties can be evaluated by the theoretical model without more experiments. The suggested method to develop the energy absorption diagram for corrugated boards can be used to characterize the cushioning properties and optimize the structures of corrugated sandwich structures.
基金National Natural Science Foundation of China(No.51805079)Fundamental Research Funds for the Central Universities,China(No.2232021D-15)Shanghai Science and Technology Program(No.20DZ2251400)。
文摘The quality of printed circuit board(PCB)micro-hole processing directly determines the stability of the inner and outer circuit connections.Micro-hole drilling technology is a typical method for PCB micro-hole processing.The problem of optimal control of its drilling force is one of the main factors affecting the quality of micro-hole machining.To address this problem,the thrust forces and torques in PCB drilling were first modeled and analyzed,and the corresponding prediction models were established.The drilling force analysis was carried out through the micro-hole drilling experiment,the specific cutting energy under different feed rates was calculated,the influence of the size effect was clarified,and the accuracy of the prediction model was verified.The result shows that during the drilling of glass fiber cloth,changes in the material removal mechanism are induced as the feed per revolution is varied.When the feed per revolution is less than the tool edge radius,the glass fiber is not cut by the main cutting edge,but is crushed and broken.When the feed per revolution is greater than the radius of the tool edge,the glass fiber is cut by the main cutting edge.At the same time,the established analytical model can accurately reflect the influence of the size effect on the drilling torque in PCB micro-hole drilling,and the error is within 10%.This method has certain practical application value in controlling PCB micro hole processing quality.
文摘针对目前国内一些保温材料虽具有较好的热工性能,但普遍存在吸湿吸潮吸水性大的问题,作者开发了憎水珍珠岩保温板,用于建筑外墙内保温和屋面保温。该板密度:220 kg/m^3,抗压强度:0.6～0.9 MPa,导热系数:<0.065 W/(m·K),憎水率:≥98%。应用实践表明:240 mm 砖墙内贴50 mm 该板,平均传热系数为0.74 W/(m^2·K),满足节能50%的要求;用于屋面保温:60 mm 和80 mm 厚憎水珍珠岩保温板的热工性能分别优于200 mm 和250 mm 厚的加气混凝土块;且降低造价。文章还介绍了该板的生产工艺和施工工艺,并进行了经济、技术分析。
文摘为解决某车型后立柱外板成形中出现的成形不足、起皱和破裂等问题,采用中心复合试验设计(CCD)和数值模拟相结合的方法,分析成形过程中拉延筋阻力系数和压边力对下部立柱外板成形质量的影响规律。并以成形性能Z_1、流入量Z_2和零件厚薄均匀性Z_3为优化目标,以拉延筋阻力系数和压边力为优化因素,借助Design-Expert、MATLAB等软件,构建4因素5水平的二阶响应面模型,再采用多目标优化求得最优工艺参数组合:拉延筋X_1=0.60、X_2=0.61、X_3=0.64和压边力F_0=390 k N。实际生产结果表明,采用最优的生产工艺参数组合,可获得厚度均匀、无破裂无起皱的后立柱外板零件。
