Abstract:In order to study the effect of stitching density, tow size of the suture and diameter of the stitching hole on the shear property of the stitched three-dimensional woven composite/titanium hybrid board stitching connection structure, seven groups of samples with different stitching densities, tow size of the suture and diameter of the stitching hole were tested. A reference group whose samples were unstitched was also tested to show the effect of stitching on the joint. Different failure modes of the lap zone with different stitching parameters were observed in in-situ meso-experiment, and the damage morphologies of the characteristic points on the load-displacement curve were given. The result shows that increasing tow size of the suture and increasing stitching density can both increase the failure load of the hybrid joint. Increasing the stitching density is proved more effective in improving the failure load. Doubling the stitching density can increase the failure load of the stitched joint about 82.0%. Doubling the tow size of the suture can only increase the failure load of the joint about 24.3%; Whether the diameter of the stitching hole is 2 mm or 4 mm do not influence the bearing capacity of the structure obviously, and when the stitching hole diameter reaches 6 mm, the bearing capacity is reduced due to the low strength of the epoxy resin in the gap between stitching hole and suture. It is dangerous to increase diameter of stitching hole above 4 mm; the shear failure of the stitched three-dimension woven composite/titanium alloy hybrid structure is observed by mesoscopic mechanical test. Composite/titanium alloy interface failure, crack initiation and extension in composite or in lap zone and failure of the lap zone are the three main stages of the structure failure observed in the test; The suture failure in the connect zone includes suture pull out and suture cut off. There are three failure modes of the lap zone observed in test. In suture cut off mode, all sutures in lap zone are cut off. The position at which the suture is cut is related to the diameter of the stitching hole. In suture cut off/pull out mixed mode, some of the interface between suture and three-dimension woven composites fail and the suture is partly or completely pull out. In the group with high stitching density, sutures near the end of the three-dimension woven composite crush the composite and extrude out of the composite. Stitching density is the major factor in the failure mode of the joint.
[1] 乔海涛,梁滨,张军营,等.先进复合材料结构胶接体系的研发与应用[J].材料工程,2018,46(12):38-47. QIAO H T, LIANG B, ZHANG J Y, et al. Development and application of adhesive materials for advanced composite bonding[J]. Journal of Materials Engineering, 2018,46(12):38-47.
[2] 曲春艳,李琳,王德志.钛合金胶接表面处理研究[J].材料工程,2010(12):82-85. QU C Y, LI L, WANG D Z. Study on surface treatment of titanium alloy for adhesive bonding[J]. Journal of Materials Engineering, 2010(12):82-85.
[3] WANG S N, LI Y, GUO Y, et al. Development of a two-component structural adhesive for bonding of metals and polymeric composites[J]. International Journal of Adhesion and Adhesives, 2019, 90:38-46.
[4] CAO Y J, CAO Z Q, ZUO Y J, et al. Numerical and experimental investigation of fitting tolerance effects on damage and failure of CFRP/Ti double-lap single-bolt joints[J]. Aerospace Science and Technology, 2018, 78:461-470.
[5] 余海燕,李佳旭,周辰晓. 碳纤维复合材料与高强度钢板螺栓连接拉伸性能[J]. 同济大学学报(自然科学版), 2018, 46(5):680-686. YU H Y, LI J X, ZHOU C X. Tensile properties of bolted joints between CFRP and high strength steel plate[J]. Journal of Tongji University(Natural Science), 2018, 46(5):680-686.
[6] VANDERKLOK A, DUTTA A, TEKALUR S A. Metal to composite bolted joint behavior evaluated at impact rates of loading[J]. Composite Structures, 2013, 106:446-452.
[7] GERENDT C, DEAN A, MAHRHOLZ T, et al. On the progressive failure simulation and experimental validation of fiber metal laminate bolted joints[J]. Composite Structures, 2019, 229:111368.
[8] NGUYEN A T T, BRANDT M, FEIH S, et al. Pin pull-out behavior for hybrid metal-composite joints with integrated reinforcements[J]. Composite Structures, 2016, 155:160-172.
[9] TANG H Q, LIU L Q. A novel metal-composite joint and its structural performance[J]. Composite Structures, 2018, 206:33-41.
[10] BIGAUD J, ABOURA Z, MARTINS A T, et al. Analysis of the mechanical behavior of composite T-joints reinforced by one side stitching[J]. Composite Structures, 2018, 184:249-255.
[11] 李梦佳,陈普会,孔斌,等. 缝合参数对复合材料T型接头拉脱承载能力的影响[J]. 复合材料学报, 2016, 33(3):681-688. LI M J, CHEN P H, KONG B, et al. Effects of parameters of stitching on pull-off carrying capacity of composite T-joint[J]. Acta Materiae Compositae Sinica, 2016, 33(3):681-688.
[12] 焦亚男,李嘉禄,韩雪梅,等. 缝合连接三维编织复合材料拉伸性能实验研究[J]. 复合材料学报, 2008, 25(1):127-132. JIAO Y N, LI J L, HAN X M, et al. Experimental investigation on tensile property of stitching joint 3D braided composites[J]. Acta Materiae Compositae Sinica, 2008, 25(1):127-132.
[13] 焦亚男,李嘉禄,韩雪梅.三维编织复合材料缝合连接设计及破坏机制[J].纺织学报,2008,29(6):48-51. JIAO Y N, LI J L, HAN X M. Design and destroying mechanism of stitching joint 3-D braided composites[J]. Journal of Textile Research, 2008,29(6):48-51.
[14] JAIN L K, LEONG K H, MAI Y W, et al. Effect of through-thickness stitching on the fatigue life of composite single-lap joints[J]. Applied Composite Materials, 1998, 5:399-409.
[15] GHASEMNEJAD H, ARGENTIERO Y, TEZ T A, et al. Impact damage response of natural stitched single lap-joint in composite structures[J]. Materials & Design, 2013, 51:552-560.
[16] MOURITZ A P, COX B N. A mechanistic approach to the properties of stitched laminates[J]. Composites:Part A, 2000, 31(1):1-27.
[17] AN W J, KIM C H, CHOI J H, et al. Static strength of RTM composite joint with Ⅰ-fiber stitching process[J]. Composite Structures, 2019, 210:348-353.