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无损检测技术能对木材空洞缺陷进行快速且准确的检测,现存的各种检测技术都有一定的优缺点,因此有必要对它们进行试验和对比。以福建杉木圆盘为对象,研究不同面积、不同轮廓形状的空洞缺陷对电阻和应力波断层成像技术的影响,比较两种检测技术的缺陷图像与实际缺陷图像的差异。结果表明:1电阻和应力波检测技术均能直观显示木材内部缺陷,其检测精度会受到空洞缺陷面积、轮廓形状以及截面积比率影响;2当空洞实际面积与被测木材截面积比率从4.90%上升到44.05%时,电阻成像系统显示的缺陷图像面积与实际缺陷面积相对误差从34.03%下降到11.69%,应力波成像系统显示缺陷图像面积与实际缺陷面积相对误差从46.41%下降到14.88%;3缺陷轮廓形状对两种成像均有一定影响。对于电阻成像,近圆形的空洞成像精度低于狭长形的空洞缺陷,在电阻成像中,除了扇形和圆形缺陷外,其余的空洞缺陷形状均不能被明显地检测出,但是应力波成像中,狭长形的扇形缺陷能够比较清晰地被系统显示。研究表明:电阻断层成像法对于空洞缺陷的检测比应力波断层成像法灵敏,且图像检测精度也比应力波断层成像法高;而对于缺陷轮廓的识别能力,应力波断层成像法要优于电阻断层成像法。
Non-destructive testing technology can detect the wood hole defects quickly and accurately, and the various existing detection techniques have some advantages and disadvantages. Therefore, it is necessary to test and compare them. Fujian Fir Disc was used to study the influence of hole defects of different area and contour shape on the imaging technology of resistance and stress wave tomography. The difference between the defect image and the actual defect image of the two detection techniques was compared. The results show that: 1 resistance and stress wave detection technology can visually display the internal defects of wood, the detection accuracy will be affected by the hollow defect area, the shape of the profile and the cross-sectional area ratio; 2 when the ratio of the actual area of the void to the cross-sectional area of the tested wood is from 4.90% The relative error between the defect image area and the actual defect area displayed by the resistance imaging system decreased from 34.03% to 11.69% when it rose to 44.05%. The stress wave imaging system showed that the relative error between the defect image area and the actual defect area decreased from 46.41% to 14.88%. 3 defect contour shape of both imaging have a certain impact. For resistive imaging, the imaging accuracy of near-circular cavity is lower than that of narrow-shaped cavity. In resistance imaging, except for the fan-shaped and circular defects, the shape of the other hollow defects can not be obviously detected. However, in stress wave imaging , Narrow fan-shaped defects can be more clearly displayed by the system. The research shows that the resistivity tomography is more sensitive than the stress wave tomography to the detection of the cavity defects and the accuracy of image detection is higher than that of the stress wave tomography. However, the stress wave tomography is better than the resistivity tomography Imaging method.