Development of high temperature drying system supported by AE for boxed heart heavy timber without check

AE支持的箱心重材免检高温干燥系统的开发

• 批准号: 13660168
• 负责人: FUJIMOTO Noboru
• 金额: $ 2.24万
• 依托单位: Kyushu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13660168/
• 关键词: Japanese cedar; Boxed heart heavy timber; Surface check; Internal check; Acoustic emission; Monitoring drying check; 心持ち大断面材; AE; 表面応力; 木材乾燥

In wood drying, the sensing technology of the surface checks has not been established. Though the use of the AE method is experimentally tried in the wood drying, the research example in the heavy timbers does not especially include the testing example because the attenuation of the AE wave in wood is remarkable.In this research, proof of monitoring checks by AE was tried under assumption that the first check position was able to be specified by damaging by nailing. The center of the flat grain of the boxed-heart square timber was nailed, and AE of the nail was measured during drying. AE was generated regardless of the checks during steaming. But it was thought that the surface checks were able to be monitored because the surface checks were caused in the one that an increase in the AE generation for a short time was seen during drying afterwards.In monitoring internal checks of the boxed-heart square timber, the nail deeply drove at the position of 3cm from the edge of face and AE of the nail was measured because there was a feature had often generated like the diagonal from pith. AE was recognized as well as the measurement of the surface check during steaming though no internal check was generated. In the condition that internal checks occurred, increases in the AE generation were comparatively seen for a long term since a day after steaming. That is, it was guessed that internal checks would not occur in a short time at a time but progress little by little comparatively for a long time since middle term of drying.

在木材干燥中，表面裂纹的传感技术尚未建立。虽然在木材干燥中进行了AE法的试验，但由于AE波在木材中的衰减非常显著，因此在重型木材中的研究实例中没有特别包括试验实例。本研究中，在假设第一次检查位置能够通过钉击损伤来指定的情况下，尝试了通过AE进行监测检查的证明。对箱心方材的平纹中心进行钉扎，并在干燥过程中测量钉扎声发射。无论蒸汽处理过程中的检查如何，都会产生AE。但人们认为，表面裂纹能够被监测，因为表面裂纹是在干燥过程中短时间内AE产生增加的情况下引起的。在监测箱心方材的内部裂纹时，在距面边缘3cm的位置处深深打入髓内钉，并测量髓内钉的AE，因为通常会产生类似与木髓成对角线。在蒸汽处理过程中识别出AE以及表面检查的测量结果，但未产生内部检查。在发生内部检查的情况下，从蒸汽处理后一天开始，AE产生的增加相对较长。也就是说，推测内部裂纹不会在短时间内一次发生，而是从干燥中期开始相对长时间地逐渐进展。