GLARE层板层间剪切失效行为与机理研究

发布时间：2018-05-12 05:22

本文选题：GLARE层板 + 层间剪切性能　；参考：《南京航空航天大学》2017年硕士论文

【摘要】：GLARE层板因其优异的力学性能和减重效果,在飞机蒙皮等部位成功实现商业应用。GLARE层板由铝合金薄板和复合材料交替铺层热压固化而成,且铺层具有可设计性,导致其界面体系复杂。层间抗剪切能力是该型层板重要的性能之一,但尚未有合适的测试方法能有效评价GLARE层板的层间剪切性能。本文研究GLARE层板短梁法(short-beam shear test method,SBS)层间剪切失效行为,分析不同失效模式的机理,探讨合适的跨厚比(length-to-thickness,L/h)以使改进后的短梁法适用于GLARE层板层间剪切性能评价。同时,研究GLARE层板双梁法(double short-beam shear test method,DBS)层间剪切失效行为,论证双梁法用于GLARE层板层间剪切性能评价的可行性。本文对GLARE层板短梁法层间剪切失效行为与机理进行研究。制备了四种典型铺层的3/2结构GLARE层板:GLARE 2A,GLARE 3,GLARE 4A和GLARE 6。研究了不同铺层GLARE试样在短梁法层间剪切试验时不同跨厚比条件下的失效模式和力学行为,并对每种失效模式进行机理分析,探讨适合该型层板层间剪切性能评价的跨厚比。本研究中所选的跨厚比范围为5-12。研究结果表明,当跨厚比为8时,四种铺层GLARE试样都发生纯剪切失效模式,即发生在中性层附近的层间脱粘分层,且表观层间剪切强度值稳定可靠,能有效表征GLARE层板的层间剪切性能。而跨厚比为5的短梁法层间剪切试验获得的是挤压-剪切失效模式,且层间剪切强度值较大。跨厚比达到10或更大后,试样发生了弯曲破坏,表观层间剪切强度值降低。通过对不同模式的失效机理进行研究分析,证明跨厚比为8可用来评价GLARE-3/2层板层间剪切性能。同时,本文研究了GLARE层板双梁法层间剪切的失效行为与机理,论证双梁法用于该型层板层间剪切性能评价的可行性。自行设计了双梁法的试验夹具,夹具的精度和性能满足试验要求。具体研究了不同跨厚比条件下试样的失效行为和失效机制。研究结果表明,由于双梁法存在纯剪切点,试样在本文跨厚比(L/h=5-8)范围内进行双梁法层间剪切试验都能发生有效的层间剪切失效。GLARE 2A和GLARE 6表现为中间铝合金层与复合材料层之间的脱粘分层;GLARE 3的失效为90°复合材料层与中间铝合金层之间的脱粘分层,以及90°复合材料层在压头处的局部开裂;GLARE 4A分层失效发生在0°复合材料层与中间铝合金层之间,但90°复合材料层未有明显破坏。在较小跨厚比时,试样在中间支座和压头处有应力集中。此外,双梁法剪切试验获得的表观层间剪切强度值大于短梁法,但两种方法之间不存在排它性。此外,为了研究GLARE层板层间剪切失效行为结构演变规律以及跨厚比的结构适用性,制备每种铺层层板的4/3,5/4,6/5结构。研究结果表明,5/4和6/5的GLARE 3以及GLARE 4A在跨厚比为7时进行短梁法剪切试验能发生有效的层间剪切失效。结构不影响GLARE 2A短梁法表观层间剪切强度试验值,而GLARE 3和GLARE 6的短梁法表观层间剪切强度试验值随着层板厚度增加而降低。对于双梁法,GLARE 2A层板随着结构增厚层间剪切强度试验值稍有下降,GLARE 3和GALRE 6同样呈现下降趋势。双梁法和短梁法结构演变规律的一致性证明了短梁法跨厚比选取的合理性,以及双梁法用于GLARE层板层间剪切性能评价的可行性。
[Abstract]:Because of its excellent mechanical properties and weight reduction effect, the commercial application of the GLARE laminates has been successfully achieved by the hot pressing of the alternating layer of aluminum alloy sheet and composite material in the surface of the aircraft, and the interface system is complex. The interlayer shear resistance is one of the most important properties of the type laminate, but it is still one of the most important properties of the laminates. No suitable testing method can effectively evaluate interlaminar shear properties of GLARE laminates. This paper studies the interlaminar shear failure behavior of the GLARE laminate short beam method (short-beam shear test method, SBS), analyzes the mechanism of different failure modes, and discusses the appropriate cross thickness ratio (length-to-thickness, L/h) to make the improved short beam method applicable to the GLARE laminar layer. The interlaminar shear failure behavior of GLARE laminates (double short-beam shear test method, DBS) is studied. The feasibility of using the double beam method to evaluate the interlaminar shear properties of GLARE laminates is demonstrated. In this paper, the interlayer shear failure behavior and mechanism of the GLARE laminate short beam method are studied. Four kinds of typical layer 3/2 are prepared. Structural GLARE laminate: GLARE 2A, GLARE 3, GLARE 4A and GLARE 6., the failure mode and mechanical behavior of different layer GLARE specimens under the condition of different cross thickness ratio in short beam interlaminar shear test are studied, and the mechanism analysis of each failure mode is carried out to discuss the cross thickness ratio suitable for the evaluation of interlaminar shear performance. The cross thickness ratio range of 5-12. shows that, when the cross thickness ratio is 8, the pure shear failure mode of the four layers of layers has a pure shear failure mode, that is, the interlayer debonding layer near the neutral layer, and the apparent shear strength of the apparent interlayer is stable and reliable, and the interlayer shear properties of the GLARE laminates can be effectively characterized. The interlayer shear test with the span thickness ratio of 5 is the short beam method. The compression shear failure mode was obtained, and the interlayer shear strength was larger. After the cross thickness ratio reached 10 or more, the specimen occurred bending failure and the apparent shear strength decreased. Through the study and analysis of the failure mechanism of different modes, it was proved that the cross thickness ratio of 8 could be used to evaluate the interlaminar shear properties of GLARE-3/2 laminates. In this paper, the failure behavior and mechanism of interlaminar shear between GLARE laminates and double beams are studied. The feasibility of the double beam method for interlaminar shear performance evaluation is demonstrated. A double beam test fixture is designed by ourselves. The accuracy and performance of the fixture meet the requirements of the test. The failure behavior and failure mechanism of the specimens under the conditions of different cross thickness ratio are studied. The results show that, due to the existence of the pure shear point in the double beam method, the effective interlaminar shear failure of the sample in the cross thickness ratio (L/h=5-8) of this paper can have effective interlaminar shear failure.GLARE 2A and GLARE 6 as the debonding layer between the intermediate aluminum alloy layer and the composite layer, and the failure of the GLARE 3 is 90 degree composite layer and medium. The debonding stratification between the aluminum alloy layers and the partial cracking of the 90 degree composite layer at the pressure head; the GLARE 4A stratification failure occurs between the 0 degree composite layer and the intermediate aluminum alloy layer, but the 90 degree composite layer has no obvious damage. The apparent interlayer shear strength obtained by the test is greater than the short beam method, but there is no exclusion between the two methods. In addition, in order to study the structure evolution law of the interlayer shear failure behavior of GLARE laminates and the structural applicability of the cross thickness ratio, the 4/3,5/4,6/5 structure of each layer plate is prepared. The results show that the GLARE 3 and GLARE of 5/4 and 6/5 are GLARE and GLARE. 4A can have effective interlayer shear failure in the short beam shear test when the cross thickness ratio is 7. The structure does not affect the apparent shear strength test value of the GLARE 2A short beam method, while the apparent shear strength test value of the short beam method of GLARE 3 and GLARE 6 decreases with the increase of the thickness of the laminar plate. To the double beam method, the GLARE 2A laminate is thickened with the structure. The test value of interlayer shear strength decreases slightly, the GLARE 3 and GALRE 6 also show a downward trend. The consistency of the structure evolution law of the double beam method and the short beam method proves the rationality of the selection of the short beam method and the feasibility of the double beam method for the evaluation of the interlaminar shear performance of the GLARE laminates.

【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33

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