Effect of Mixed Mode at the Crack Tip on the Interfacial Fatigue Crack Behavior of Sandwich Beams with Aluminum Foam Cores

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Project title

Code/計畫編號

MOST103-2221-E019-005

Translated Name/計畫中文名

裂縫尖端混合負載模式對具有發泡鋁芯材之三明治樑界面疲勞裂縫行為之影響

Project Coordinator/計畫主持人

Yi-Ming Jen

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Mechanical and Mechatronic Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=8314331

Year

2014

Start date/計畫起

01-08-2014

Expected Completion/計畫迄

31-07-2015

Bugetid/研究經費

713千元

ResearchField/研究領域

機械工程
材料科技

本計畫將探討裂縫前端混合負載模式對以封閉型發泡鋁為芯材、玻璃纖維強化聚丙烯複材積層板為面板的三明治樑在承受靜態及疲勞負荷下界面脫膠裂縫行為的影響。計畫分為兩大部分。首先進行一系列有限元素法分析，模擬含有預置界面裂縫之三明治結構，在利用混合負載模式彎矩法施加靜態負荷下試片的柔度，並進而求得應變能釋放率。有限元素法結果的正確性可以與理論解相互比較來驗證。裂縫前端混合負載模式可以利用有限元素法的結果來計算，並以相位角來表示。在實驗部分，則利用混合負載模式彎矩法求取在不同混合負載模式下，預裂三明治試片的極限負荷及裂縫尖端的臨界應變能釋放率。實驗中裂縫尖端的混合負載模式可以利用調整夾具桿臂距離而得。研究中同時將探討不同試片製作參數對預裂三明治試片在不同混合負載模式下之臨界應變能釋放率的影響。這些參數包括：芯材相對密度、芯材高度、複材面板堆疊層數及堆疊方向。第二部分的研究將以第一部分的研究結果為基礎，針對預裂之三明治結構，利用混合負載模式彎矩法施加週次疲勞負荷，探討不同混合負載模式對於裂縫成長速率與應變能釋放率範圍間關係的影響。研究中並將瞭解不同試片製作參數，對預裂三明治試片在不同混合負載模式下裂縫成長速率與應變能釋放率範圍間關係的影響。"The effect of the mixed modes at the crack tips on the face/core debonding behaviors of the sandwich beams with glass-fiber reinforced polypropylene laminate faces and aluminum foam cores subjected to the static and cyclic loading will be studied in this project. The project consists two parts. First, a serial of finite element analyses will be performed to simulate the compliance of the pre-cracked sandwich beams under the monotonic loading by using the mixed-mode bending (MMB) method. The strain energy release rate can be also obtained based on the results of the finite element analysis. The accuracy of the finite element analysis can be evaluated by comparing the simulated results with the analytical solutions. Furthermore, the mixed mode at the crack tip can be obtained based on the results of the finite element analysis and expressed as the phase angle. Besides, the effect of the mixed modes at the crack tips on the ultimate loads and the critical strain energy release rates of the pre-cracked sandwich beams will be investigated experimentally using the MMB method. In the experiments, the mode mixity at the crack tip can be set by adjusting the distance of level arm of the MMB apparatus. The effects of the manufacturing variables on the critical strain energy release rates of the pre-cracked sandwich beam specimens under various crack-tip mixed modes will be studied herein. These variables include the relative density of the foamed core, the core height, the number of the plies of the composite face, and the direction of the plies of the composite face. Based on the results of the first part of the project, the effect of the mixed modes at the crack tips on the relationship between the fatigue crack propagation rate and the strain energy rate range of the pre-cracked sandwich beam subjected to the cyclic loading will be studied experimentally using the MMB method. Similarly, the effects of manufacturing variables on the fatigue crack propagation behaviors of the pre-cracked sandwich beam specimens under different crack-tip mixed modes will be also investigated. "

Keyword(s)

疲勞
混合負載模式彎矩法
熱塑性
發泡鋁
三明治樑
脫膠
界面裂縫
柔度
相位角
混合負載模式
應變能釋放率
裂縫成長速率
有限元素法
fatigue
mixed-mode bending (MMB)
thermoplastic
aluminum foam
sandwich beam
debonding
interfacial crack
compliance
phase angle
mode-mixity
strain energy release rate
crack propagation rate
finite element method.

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Effect of Mixed Mode at the Crack Tip on the Interfacial Fatigue Crack Behavior of Sandwich Beams with Aluminum Foam Cores

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