试验发现了钢绞线结构中L（0,1）模态导波存在陷频这一固有声学特性,由此提出一种钢绞线拉力检测新方法。为测试钢绞线中导波陷频特性与拉力的关系,研制了一款柔性低频磁致伸缩传感器,可在30~160 k Hz范围内激励/接收L（0,1）模态导波...试验发现了钢绞线结构中L（0,1）模态导波存在陷频这一固有声学特性,由此提出一种钢绞线拉力检测新方法。为测试钢绞线中导波陷频特性与拉力的关系,研制了一款柔性低频磁致伸缩传感器,可在30~160 k Hz范围内激励/接收L（0,1）模态导波。在直径17.8 mm和15.2 mm的两种7芯钢绞线上进行导波陷频检测试验,结果表明陷频特征频率与拉力的自然对数值呈良好线性关系,陷频旁侧峰值比随拉力增大而线性增加。试验中1 k N的拉力增量（应力增量约3 MPa）引起的声学参数（陷频特征频率和陷频旁侧峰值比）变化可被检测到并较好的符合标定关系方程。在额定工作载荷内,拉力估算相对误差小于1.5%,这表明新方法具有较高的拉力检测精度。同时,依据试验所得结论,给出了钢绞线结构中L（0,1）模态导波陷频中心频率与拉力关系的修正公式。新方法实施过程简洁,具有很好的工程应用前景。展开更多
In recent years, the zero-span tension technique of paper and pulp-making industry was applied to wood industry for indirectly testing the longitudinal tensile strength of tracheids. In this paper, this technique was ...In recent years, the zero-span tension technique of paper and pulp-making industry was applied to wood industry for indirectly testing the longitudinal tensile strength of tracheids. In this paper, this technique was used to test the longitudinal tension strength of tracheids for Chinese fir specimens with different widths. The results showed that average tension strength was 357.39 MPa. The order of average tension strength of tracheids was: 3 mm > 12 mm > 6 mm > 9 mm > 7.5 mm. But, earlywood samples frequently contained a little latewood and sample-making was difficult when the width of specimen was bigger, both the testing and the putting of samples were difficult when the width of specimen was smaller. Therefore, the width of 6 mm was chosen as the best width of specimen of Chinese fir.展开更多
Prolonged tension tcsts were caTried out by comblning elevated temperatures with declined stresses over thc range of 760-1050° C and 780-115MPa. The effects of temperature and applied stress on rupture life, and ...Prolonged tension tcsts were caTried out by comblning elevated temperatures with declined stresses over thc range of 760-1050° C and 780-115MPa. The effects of temperature and applied stress on rupture life, and the relations of temperuture, applied stress and mpture life to characteristic dimensions of coherent phases (γ matrix channel width and mpcd γ precipitate thickness), and to the elongation as well as to the cross sectional area reduction of thc tested specimens were investigated. Under all testing conditions, longittLdinal coalescence of seveml adjacent armys of γ precipitates could occur to dtherent extents along the direction of the applied stress axis in addition to their normal directional coarsening. The extent of γ Longitudinal coalescence became increased and its morphology tended to be irmpular with the increase of temperuture although the applied stresses were relatively lower.展开更多
文摘试验发现了钢绞线结构中L（0,1）模态导波存在陷频这一固有声学特性,由此提出一种钢绞线拉力检测新方法。为测试钢绞线中导波陷频特性与拉力的关系,研制了一款柔性低频磁致伸缩传感器,可在30~160 k Hz范围内激励/接收L（0,1）模态导波。在直径17.8 mm和15.2 mm的两种7芯钢绞线上进行导波陷频检测试验,结果表明陷频特征频率与拉力的自然对数值呈良好线性关系,陷频旁侧峰值比随拉力增大而线性增加。试验中1 k N的拉力增量（应力增量约3 MPa）引起的声学参数（陷频特征频率和陷频旁侧峰值比）变化可被检测到并较好的符合标定关系方程。在额定工作载荷内,拉力估算相对误差小于1.5%,这表明新方法具有较高的拉力检测精度。同时,依据试验所得结论,给出了钢绞线结构中L（0,1）模态导波陷频中心频率与拉力关系的修正公式。新方法实施过程简洁,具有很好的工程应用前景。
基金the National Natural Science Key Foundation of China "The Constructing and Application of Token System for MechanicsProperties of Wood Cell Wall (C02060102)"
文摘In recent years, the zero-span tension technique of paper and pulp-making industry was applied to wood industry for indirectly testing the longitudinal tensile strength of tracheids. In this paper, this technique was used to test the longitudinal tension strength of tracheids for Chinese fir specimens with different widths. The results showed that average tension strength was 357.39 MPa. The order of average tension strength of tracheids was: 3 mm > 12 mm > 6 mm > 9 mm > 7.5 mm. But, earlywood samples frequently contained a little latewood and sample-making was difficult when the width of specimen was bigger, both the testing and the putting of samples were difficult when the width of specimen was smaller. Therefore, the width of 6 mm was chosen as the best width of specimen of Chinese fir.
文摘Prolonged tension tcsts were caTried out by comblning elevated temperatures with declined stresses over thc range of 760-1050° C and 780-115MPa. The effects of temperature and applied stress on rupture life, and the relations of temperuture, applied stress and mpture life to characteristic dimensions of coherent phases (γ matrix channel width and mpcd γ precipitate thickness), and to the elongation as well as to the cross sectional area reduction of thc tested specimens were investigated. Under all testing conditions, longittLdinal coalescence of seveml adjacent armys of γ precipitates could occur to dtherent extents along the direction of the applied stress axis in addition to their normal directional coarsening. The extent of γ Longitudinal coalescence became increased and its morphology tended to be irmpular with the increase of temperuture although the applied stresses were relatively lower.
