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Characteristics estimation f or sintered materials by analyssis of frequency response function of mechanical bivration.

通过分析机械双振动的频率响应函数来估计烧结材料的特性。

基本信息

批准号：
06650822
负责人：
YOKOTA Masaru
金额：
$ 1.15万
依托单位：
Takaoka National College
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

项目摘要

Taking note of the fact tht precise higher order resonant frequency can be detected simply by using Fast Fourier Transform (FFT) analyzer, some attempts were made to estimate both densities and elastic moduli for the sintered iron compacts and 2024 Al alloy sintered compacts. The results obtained were as follows ;(1) Three spectrums of resonant frequencies were observed by bending vibration method. Rigid linear relationship was obtained between these resonant frequencies and sintered resonant frequency was the largest among three specturns, which seems to be advantageous for estimating the sintered density.(2) Considerable difference in elastic modulus for the sintered iron compacts was found between present and already reported results.(3) In the strain-amoplitude-independent part, the Q^<-1> measured is 1.5^-8.1x10^<-3>, which is about 10 times higher than the value of sintered iron. Moreover, after T6 treating these materials, they were found to have an even higher Q^<-1> than the as sintered materials.(4) An increase in Cu content resulted in a decrease in the Q^<-1> of both the as-sintered and T6 treated materials.(5) Damping mechanisms appeared to be relaxation due to dislocation motion and reversible multiphase boundary sliding.(6) Changes in fr during vibration at a constant amplitude correspond to those in the internal friction (Q^<-1>), and amarked decrease in Q^<-1> occurs as a result of the formation of fatigue cracks. These cracks propagate mainly along grain boundaries in as-sintered specimens, and transgranularly in T6 treated ones.

考虑到快速傅里叶变换（FFT）分析仪可以精确检测高阶谐振频率，对烧结铁质和2024铝合金烧结材料的密度和弹性模量进行了估计。所得结果如下：(1)用弯曲振动法观察了三个共振频率谱。这些谐振频率之间具有严格的线性关系，烧结谐振频率在三个频谱中最大，这似乎有利于烧结密度的估计。(2)烧结铁块的弹性模量在现有的和已经报道的结果之间有相当大的差异。(3)在与应变幅值无关的部分，测得的Q^<-1>为1.5^-8.1x10^<-3>，约为烧结铁的10倍。此外，经过T6处理后，发现这些材料比未烧结的材料具有更高的Q^<-1>。(4) Cu含量的增加导致烧结态和T6处理态材料的Q^<-1>减小。(5)由于位错运动和可逆多相边界滑动，阻尼机制表现为弛豫。(6)等幅振动时的fr变化与内摩擦（Q^<-1>）的变化相对应，并且由于疲劳裂纹的形成，Q^<-1>出现了明显的减小。这些裂纹在烧结状态下主要沿晶界扩展，而在T6处理下主要是穿晶扩展。