The contact pressure acting on the sheet/tools interface has been studied because of growing the concern about the wear of tools. Recent studies make use of numerical simulation software to evaluate and correlate this...The contact pressure acting on the sheet/tools interface has been studied because of growing the concern about the wear of tools. Recent studies make use of numerical simulation software to evaluate and correlate this pressure with the friction and wear generated. Since there are many studies that determine the coefficient of friction in sheet metal forming by bending under tension (BUT) test, the contact pressure between the pin and the sheet was measured using a film that has the ability to record the applied pressure. The vertical force applied to pin was also measured. The results indicate that the vertical force is more accurate to set the contact pressure that using equations predetermined. It was also observed that the contact area between the sheet and the pin is always smaller than the area calculated geometrically. The friction coefficient was determined for the BUT test through several equations proposed by various authors in order to check if there is much variation between the results. It was observed that the friction coefficient showed little variation for each equation, and each one can be used. The material used was the commercially pure aluminum, alloy Al1100.展开更多
为了提高应用Sylvatest-Duo超声波测量装置进行木材质量和缺陷检测的精度,研究了该装置的探针与木材接触方式(探针触式)及其计示压强对木材中超声波传播速度和信号能量衰减幅度的影响,确定了测量过程中宜采用的最佳探针触式和最佳计示...为了提高应用Sylvatest-Duo超声波测量装置进行木材质量和缺陷检测的精度,研究了该装置的探针与木材接触方式(探针触式)及其计示压强对木材中超声波传播速度和信号能量衰减幅度的影响,确定了测量过程中宜采用的最佳探针触式和最佳计示压强。以美国红松Pinus resinosa的小规格试样材(25.4 mm×25.4 mm×407.0 mm)为研究对象,采用单因素重复试验,经SPSS统计分析中多元检验的研究结果表明:不同的探针触式对超声波测量结果影响显著(P值为0.000),探针-木材的"持续性接触"比"非持续性接触"测量偏差小,检测效果稳定;在探针"持续性接触"方式下,超声波的传播速度和信号能量衰减幅度随着计示压强增大而增加,在计示压强为275.8 k Pa(40 psi)时,两者趋于稳定。因此,建议在应用Slyvatest-Duo进行木材超声波测量过程中,宜保持探针与木材持续性接触,同时采用275.8 k Pa的计示压强,可达到最优检测精度。展开更多
文摘The contact pressure acting on the sheet/tools interface has been studied because of growing the concern about the wear of tools. Recent studies make use of numerical simulation software to evaluate and correlate this pressure with the friction and wear generated. Since there are many studies that determine the coefficient of friction in sheet metal forming by bending under tension (BUT) test, the contact pressure between the pin and the sheet was measured using a film that has the ability to record the applied pressure. The vertical force applied to pin was also measured. The results indicate that the vertical force is more accurate to set the contact pressure that using equations predetermined. It was also observed that the contact area between the sheet and the pin is always smaller than the area calculated geometrically. The friction coefficient was determined for the BUT test through several equations proposed by various authors in order to check if there is much variation between the results. It was observed that the friction coefficient showed little variation for each equation, and each one can be used. The material used was the commercially pure aluminum, alloy Al1100.
文摘为了提高应用Sylvatest-Duo超声波测量装置进行木材质量和缺陷检测的精度,研究了该装置的探针与木材接触方式(探针触式)及其计示压强对木材中超声波传播速度和信号能量衰减幅度的影响,确定了测量过程中宜采用的最佳探针触式和最佳计示压强。以美国红松Pinus resinosa的小规格试样材(25.4 mm×25.4 mm×407.0 mm)为研究对象,采用单因素重复试验,经SPSS统计分析中多元检验的研究结果表明:不同的探针触式对超声波测量结果影响显著(P值为0.000),探针-木材的"持续性接触"比"非持续性接触"测量偏差小,检测效果稳定;在探针"持续性接触"方式下,超声波的传播速度和信号能量衰减幅度随着计示压强增大而增加,在计示压强为275.8 k Pa(40 psi)时,两者趋于稳定。因此,建议在应用Slyvatest-Duo进行木材超声波测量过程中,宜保持探针与木材持续性接触,同时采用275.8 k Pa的计示压强,可达到最优检测精度。
