CUHK electronic theses & dissertations collection

It has been found that the composites of carbon nanotubes (CNTs) and epoxy resin could greatly enhance damping ability while the stiffness is kept at a very high level. In this research, carbon nanotube enhanced epoxy resin is fabricated. The dynamic properties of the nanotube composites are evaluated. A testing apparatus for obtaining composite dynamic properties is set up and measurement procedures are given. Multiple groups of specimens are made for investigations. In particular, the loss factors together with dynamic stiffness are measured for the specimens with different CNT weight ratio. Experimental results show that CNT additive can provide the composite with several times higher damping as compared with pure epoxy. The composite is much stiffer than viscoelastic material (VEM) while the damping is comparable when strain is above certain level. In order to further study the damping mechanism of the CNT composite, models are developed. Composite unit cell models containing single CNT segments are built by using finite element method (FEM). Models with varying CNT orientations are considered in order to describe the behaviors of the randomly oriented CNTs inside the epoxy matrix. Composite loss factors are calculated based on the average ratio of the unit cell energy loss to the unit cell energy input. Calculated loss factors under different strain levels are compared to experimental results. With the validated model, parametric study is thereafter performed. Parameters such as CNT dimensions and CNT alignment orientation are studied. Those factors lead to higher composite damping capacity are identified.by Dai, Ruoli."September 2007."Adviser: Wei-Hsin Liao.Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4978.Thesis (Ph.D.)--Chinese University of Hong Kong, 2007.Includes bibliographical references (p. 93-97).Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Abstracts in English and Chinese.School code: 1307