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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.

利用快速傅里叶变换（FFT）分析仪可以简单地检测出高次共振频率，并对铁烧结体和2024铝合金烧结体的密度和弹性模量进行了估算。研究结果如下：（1）用弯曲振动法观察到三个共振频率谱。三种共振频率之间存在严格的线性关系，烧结体的共振频率最大，有利于烧结体密度的估算。(2)烧结铁压坯的弹性模量存在很大的差异，目前和已经报道的结果之间。(3)在与应变幅值无关的部分，测得的Q^<-1>为1.5^-8.1 × 10 ^-3<-3>，这比烧结铁的值高约10倍。此外，在T6处理这些材料之后，发现它们具有比烧结材料更高的Q1<-1>。(4)Cu含量的增加导致<-1>烧结态和T6处理的材料两者的Q2降低。(5)其阻尼机制为位错运动引起的弛豫和可逆的多相边界滑移。(6)在等幅振动过程中，fr的变化与内摩擦（Q^）的变化相对应<-1>，而由于疲劳裂纹的形成，Q^会显著降低<-1>。这些裂纹在烧结态试样中主要沿沿着晶界扩展，在T6处理试样中主要沿穿晶扩展。