在本篇論文裡，我們主要採用兩種方式來研究高阻尼高勁度 (HDHS) 的複合材料。一種是利用傳統方法採用複合理論將附高勁度性質的金屬與含高阻尼的高分子材料做結合。另一種則是利用固態-固態相變化材料，如二氧化釩 (VO2) 與鈦酸鋇 (BaTiO3)，經過相變溫度時會產生負勁度的想法。在傳統方式方面，我們將高分子材料，如熱熔膠 (HMA) 與 polyamide 塞入中空不銹鋼中形成複合材料。此種材料雖然非為最理想高阻尼高勁度的複合材料，但這種方法因為金屬為基體而能確保此複合材料產生一定的勁度，且其整體消散能力也會有明顯改善。研究發現，少量的高分子加入金屬的複合材料雖然會稍稍減少整體勁度，但將大大增加材料的消散能力。透過共振超音波頻譜實驗(RUS)，我們發現扭轉模態的共振頻率不會因為中空洞的大小而有所改變，如體積V=25mm x 25mm x 25mm 的不鏽鋼立方體扭轉模態的共振頻率皆在 57 kHz 左右。複合材料的所增加的高分子材料越多時，材料的消能能力也越好，而且塞polyamide比塞入HMA的消散能力更佳。對於孔洞尺寸 24mm 的不鏽鋼而言，含polyamide的tan delta為3.952x10^{-2}比含HMA的還大，約2.1517x10^{-2}。而在負勁度複合材料方面，我們將相變材料放入高分子材料中。透過動態剪切流變儀 (DSR)，我們發現只在某些情況時複合材料在不減少勁度下會增加阻尼，我們推測可能是高分子基體的勁度不夠，以至於無法將相變材料之變化傳送出來。介由動態剪切流變儀，我們發現以 polyamide 為基體，二氧化釩為內含物，依體積百分比 5% 比例混合的複合材料在經過相變溫度附近時 tan delta約增加 0.0264，但其他試體皆沒發現，我們推測內含相變材料的多寡與基體的勁度將決定於是否能觀察到相變現象。

In this research, two approaches are adopted to study high damping and high stiffness (HDHS) composites. One utilizes the conventional method in the viscoelastic composite theory to combine metallic materials with polymer, and the other adopts the negative-stiffness concept through phase-transforming particulate inclusions such as VO2 and BaTiO3. For the conventional method, the polymers, such as hot melt adhesive (HMA) and polyamide, are embedded into stainless steel, as a core, to form composite materials. Although this may not yield ideal HDHS composites, this approach ensures the outer surface of the composite as stiff and high strength as the metal matrix. Its overall damping is significantly improved, as oppose to its metal counterpart. It is found that, with small amount of polymer inclusion, the steel-polymer composites exhibit large increases in loss tangent, in expense of reducing overall modulus through the identification of resonant peaks in the low frequency regime. Through resonant ultrasound spectroscopy (RUS) experiments, we found that the torsional resonant frequency in relation to the hole size in the steel cubes. For the stainless steel cube with a volume of V=25mm x 25mm x 25mm cube, the constant torsion resonant frequency was around 57 kHz. Loss tangent increases as the volume of polymer increase, and the tan delta of stainless steel with polyamide is larger than that of steel with the HMA inclusion. For the steel-polymer composite with a hole size of 24 mm, its tan delta with polyamide inclusion is 3.952x10^{-2} larger than the hollow stainless steel cube, and is 2.1517x10^{-2} larger than that of steel with HMA inclusion. As for the negative-stiffness composites, the phase-transforming particles are placed in the polymers. Experimental investigations with the resonant ultrasound spectroscopy and dynamic shear rheometer are conducted. Phase-transforming particles in the polymer matrix, in some cases, show increase of damping, but no effects on modulus. It is hypothesized that the stiffness of polymer matrix may not be large enough to dance with the particulate inclusions in the vicinity of phase transformation. However, it is found that polyamide matrix, albeit weak in stiffness, still showed anomalous signals in loss tangent and dynamic modulus around the transformation temperature of the inclusions. By DSR, the polyamide+VO2 (5%) shows anomalous increase in tan delta by about 0.0264, as to all other samples. The amount of inclusions and matrix stiffness must be balanced to observe the anomalies. In addition to mechanical enhancements in the ferroelastic polymer composites, it has been reported in the literature that flexible electronic devices that contain ferroelastic inclusions in polymer matrix may exhibit unusual electrical properties.

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