Non destructive evaluation of mechanical properties by vibration

通过振动无损评估机械性能

• 批准号: 06660210
• 负责人: YOKOCHI Hideyuki
• 金额: $ 1.34万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06660210/
• 关键词: Sound intensity; Vibration intensity; Modal analysis; Wood; Ply wood; Non destructive test; Knot; Vibration mode; ヤング率; 異方性; 繊維走行; 欠点検出

The mechanical properties of wood were investigated by mode analysis, vibration intensity analysis and sound intensity analysis. The possibility of material evaluation of lumber examined from the shape of natural vibration mode and vibration/sound energy flow. The following results were obtained.(1) With the existence of a knot in a lumber, the shape of natural vibration mode changed largely.(2) Vibration energy spread toward periphery in the counterclockwise direction from a impacting force position. In the case of lower vibration modes, the flows of vibration energy vector draw the swirl shape and traveled cross the vibration nodal lines. On the other hand, in the case of higher vibration modes, vibration intensity mainly occurred in the abdomen of vibration mode. Accordingly, the flow of vibration energy corresponded to a characteristic vibration mode and a situation of occurrence and spread and consumption of vibration energy might be shown. A vibration intensity analysis could be suggested that there was the possibility of material evaluation.(3) The sound intensity corresponded to the natural vibration mode very well. The material evaluation of wood could be evaluated by the sound intensity method. The sound energy radiated cross the nodal lines and the flows of sound energy from wide radiation area to narrow radiation area in the case of higher vibration mode. It was guessed to be the one that is able to evaluate a sound characteristic such as the radiation the efficiency, the directivity of a musical instrument by the sound intensity method.

通过模态分析、振动强度分析和声强分析研究了木材的力学性能。从木材的固有振型和振动/声能流的形状来检验木材材料评价的可能性。获得了以下结果。(1)当木材中存在节块时，其固有振型发生了较大的变化。(2)振动能量从冲击力位置沿逆时针方向向周边扩散。在低阶振动模态下，振动能量矢量的流动呈漩涡状，并穿过振动节线。另一方面，在较高振动模态的情况下，振动强度主要发生在振动模态的腹部。因此，可以示出与特征振动模式对应的振动能量的流动以及振动能量的发生和传播以及消耗的情况。振动强度分析表明，有可能进行材料评估。(3)声强与固有振型有很好的对应关系。木材的材质评价可以用声强法进行评价。在高振型情况下，辐射出的声能穿过节线，并由宽辐射区向窄辐射区流动。据推测，它是一个能够评估的声音特性，如辐射的效率，乐器的指向性，通过声音强度的方法。