SolidWorks Simulation:黑膠唱片機(jī)蓋支撐墊的模態(tài)分析

宇宙立方

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" Z% {2 G. w8 C& i5 aMost audiophiles say that there is something warmer, richer, and better to the sound a vinyl record reproduces, especially compared to modern digital media. Not having listened to an album since I was young, I figured it was time to see what all the talk was about. I asked my father (long time high-end audio enthusiast) to get out his vintage 1973 JVC VL-5 turntable so we could give it a listen.
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Note: This picture is post installation of the new feet.

After all these years in storage the turntable was in great shape. Everything worked perfectly except for the vibration isolating rubber feet. Out of the four feet, three had the material break down, leaving them brittle and cracking with large sections missing or crumbling. Obviously this was not good news as the turntable needs to sit level when in use

I searched the internet for replacements but could not find any that were suitable. The next step was to make our own. Using Solidworks, my father reverse engineered a new set of feet for the turntable. After a few design iterations, the new feet were a little more stout than the originals. Thanks to SOLIDWORKS SImulation, the new feet exhibited the mechanical properties we desired.

We did not know the type of rubber used in the original foot. This was not a problem as we used Simulation Premium and the Nonlinear material models to determine a relative stiffness. By physically testing the original foot under a 2.5 lb. vertical load we measured a 0.1 in. displacement. Using Simulation and varying the material properties we found that a Shore Value of 70, gave a 0.095 in.corresponding vertical displacement. Feeling confident in the design the next step was to test for vibrational characteristics.

The turntable operates at 33 1/3, and 45 RPM. This equates to 0.556, and 0.75 Hz respectively. SOLIDWORKS Simulation Professional made it possible to test the resonant frequency of the design. The analysis results predicted the lowest resonant frequency at 16.32 Hz. This is well above the induced vibration due to the turning motor and drive mechanism, and lower than the 20,000-20 Hz most receivers output.

Next we turned to the Stratasys Polyjet line of printers that delivered an amazing print. The Polyjet printed a 70 Shore value model that behaved just like we expected. Not only did the print physically work, it looked great too.

xiaobing86203

請教大神，你這個(gè)模態(tài)分析，標(biāo)準(zhǔn)是什么樣的？是否看第一階模態(tài)頻率值？

陳小困

xiaobing86203 發(fā)表于 2017-5-16 13:13
請教大神，你這個(gè)模態(tài)分析，標(biāo)準(zhǔn)是什么樣的？是否看第一階模態(tài)頻率值？

按照樓主的意思，lowest resonant frequency at 16.32 Hz lower than the 20,000-20 Hz most receivers output.
第一階不共振，就不考率其他階了？ 還是說要分析整個(gè)裝配體？還望大神指點(diǎn)下
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宇宙立方

其實(shí)不是說一般取前5階.根據(jù)不同的對象和邊界條件,取得階數(shù)都不同.對于沒有約束的對象,前6階為剛體移動(dòng)模態(tài),頻率為0；而對于有約束的對象,則沒有剛體模態(tài).各階振型的話就是各階的振動(dòng)形態(tài),有橫向振動(dòng),扭轉(zhuǎn)振動(dòng),拉伸振動(dòng),這些需要你觀察振型來判斷.你想理解模態(tài)必須去看一些振動(dòng)學(xué)的書籍.簡單的講物體的實(shí)際振動(dòng)是各階模態(tài)的疊加效果.物體理論上有無窮階模態(tài),振動(dòng)是這無窮階模態(tài)的疊加.但是實(shí)際上各階模態(tài)對系統(tǒng)振動(dòng)的貢獻(xiàn)度不同,一般前幾階比較大,越往后越小,所以一般截取前面的模態(tài).