基于超声波无损检测技术的侧压竹集成材力学性能试验研究

Mechanical Properties of Sidepressed Bamboo laminated lumber Based on Ultrasonic Non-destructive Testing Technology

探究超声波传播速度与侧压竹集成材力学性能(抗弯弹性模量和抗弯强度)之间的关系模型,结合密度计算出的动态弹性模量和抗弯弹性模量之间的关系模型,为超声波无损检测侧压竹集成材的力学性能提供理论依据。以侧压竹集成材为研究对象,利用超声波微秒计测量仪,通过超声波传播测量试验,得到了超声波在侧压竹集成材和竹板小试样中传播速度,并绘制出侧压竹集成材超声波传播速度的等值线分布图。利用密度计测量竹板小试样的密度和超声波波速计算竹板小试样的动态弹性模量。通过三点弯曲试验得到侧压竹集成材小试样的抗弯弹性模量和抗弯强度,回归分析超声波传播速度与抗弯弹性模量和抗弯强度,以及动态弹性模量与抗弯弹性模量之间的关系。结果表明,虽然采用相同的热压工艺参数,但各个侧压竹集成材所得到的超声波波速等值线分布图存在明显差异,说明各个侧压竹集成材的胶合效果存在差别,导致其之间的力学性能也存在一定的差别,超声波传播速度越大,表明侧压竹集成材的胶合效果或者力学性能越好;超声波波速与侧压竹集成材小试样的抗弯弹性模量和抗弯强度之间存在较好的相关性(决定系数R2分别为0.65和0.59),这说明可以通过超声波波速来合理地预测和评价侧压竹集成材小试样的抗弯弹性模量和抗弯强度;侧压竹集成材小试样的动态弹性模量与其抗弯弹性模量之间也存在良好的相关性,两者的决定系数R2为0.68,这说明也可以通过测量侧压竹集成材小试样的动态弹性模量,来对其抗弯弹性模量进行合理的预测和评价。研究表明,超声波无损检测技术是合理预测和评价侧压竹集成材力学性能的一种潜在的有效手段。

The objectives of this study were to investigate the relationship model between the ultrasonic propagation velocity and the mechanical properties(flexural elastic modulus and flexural strength)of sidepressed bamboo laminated lumber(SPBLL),as well as the relationship model between the dynamic elastic modulus and flexural elastic modulus calculated by combining the density to provide a theoretical basis for ultrasonic non-destructive testing of the mechanical properties of SPBLL.Taking SPBLL as the research object,using the ultrasonic microsecond measuring instrument,the ultrasonic propagation velocity in SPBLL and the small bamboo board sample was obtained through the ultrasonic propagation measurement test,and the contour distribution map of ultrasonic propagation speed of SPBLL was drawn.The density of the small sample of bamboo board was measured by a densitometer,and the dynamic elastic modulus of the small sample of bamboo board was calculated by using its ultrasonic wave velocity.After that,the flexural elastic modulus and flexural strength of the small SPBLL samples were obtained through the three-point bending test,and the regression analysis was performed on the relationships between the ultrasonic propagation velocity&the flexural modulus,the ultrasonic propagation velocity&flexural strength,between the dynamic elastic modulus&the flexural strength.Although the same hot-pressing process parameters were used,there were significant differences in the contour distributions of ultrasonic wave velocity obtained by each SPBLL sample.This shows that there may be differences in the gluing effect of each SPBLL sample,resulting in a certain difference in the mechanical properties between them.The higher the velocity of ultrasonic wave propagation,the better the gluing effect or mechanical properties of SPBLL.There was a good correlation between the ultrasonic wave velocity and the flexural elastic modulus and flexural strength of the small SPBLL specimen(the determination coefficients R2 were 0.65 and 0.59,respectively).This shows that the flexural elastic modulus and flexural strength of small SPBLL sample can be reasonably predicted and evaluated by ultrasonic wave velocity.There was also a good correlation between the dynamic elastic modulus and the flexural elastic modulus of the small SPBLL sample,and the coefficient of determination R2 of the two was 0.68.This shows that it is also possible to reasonably predict and evaluate the flexural elastic modulus by measuring the dynamic elastic modulus of a small SPBLL specimen.It is concluded that ultrasonic nondestructive testing technology is a potentially effective means to reasonably predict and evaluate the mechanical properties of SPBLL.