【摘要】 基于横向振动原理的锯材弹性模量测量方法具有快速、无损、足尺测量等特点。该文讨论了两端刚性简支支撑和一端刚性、一端弹性支撑两种支撑形式下,锯材弹性模量检测的理论依据。在以实际生产应用为目标的检测仪器开发中,一端支撑要包含测力传感器,用于传感锯材的重量和振动信号。结果表明:测力传感器端的支撑相当于一种弹性支撑,它会造成试件固有频率测量值比实际值低,进而给试件弹性模量测量值带来误差。这一固有频率测量值减小幅度与试件-支撑刚度比有关:试件-支撑刚度比越小,减小幅度越小。一般情况下,如果将试件-支撑刚度比控制在0~0.005范围内,则会测得足够精确的弹性模量值。更多还原

【Abstract】 Transverse vibration technique is a rapid and non-destructive method for determining the modulus of elasticity(MOE) of full size structural lumber.Two test theories of lumber MOE,including a simply supported beam with two rigid supports and a simply supported beam with one elastic support and one rigid support,were discussed in this paper.A vibration test system for practical lumber grading application usually includes a load cell,which is mounted on one of the supports to sense the vibration signals and to measure the weight of the lumber.The load cell support is a kind of elastic support,resulting in the resonant frequency smaller than the natural frequency of the lumber.Moreover,the data indicated that the smaller the specimen-to-support stiffness ratio was,the lower the decrement of the resonant frequency from the natural frequency was.The specimen-tosupport stiffness ratio is suggested to be in the range of 0——0.005 for accuracy.Therefore,this study provides useful suggestions to the development of vibration testing equipment and to the improvement of testing operation procedures.更多还原