The function between composite material layer improves a method to study progress
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1 suture craft oversews to the influence of function of suture composite material closely related composite material function and suture craft parameter, main craft parameter has: Angle of diameter of density of suture type, suture, suture, suture. Suture divides the type that it is a lock and chain, lock up type suture to be in among them generation intersects among composite material more stress concentration, chain is sutural circle music technology for many times complex, at present these two kinds of type are used lesser. Undertake improvement on the foundation that people oversews in lock type, make sutural bend little, benefit undertakes at suture and the intensity between the layer rises, at the same time on inside fiber damage is little, the stress concentration that cause is small, have relative to taller scathing allowance. Current, suture composite material basically uses suture of this kind of means. Nextpage suture density is very big to influence of the function between layer of suture composite material, concussion experiment considers to show suture density increases, composite material is statified damaged area is reduced, density increases 4 times, statified reduce 40%[15] . But oversew while, the injury that seams needle, line to create certain level to the fiber of layer plywood (fiber ruptures or fiber bends) , the function inside layer board face drops [16] . Suture density is bigger, fiber injury rate is more serious, suitable suture density talent makes suture achieves groove. Graph 1~3 gave out respectively the shear strength between the layer of suture density and suture composite material, compress the relation curve that tenacity GIC ruptures between intensity and layer [15-17] . Suture diameter increases tenacity and concussion impedance rupture between the layer that raised suture composite material, but cause the loss inside more face, make mechanical function is reduced inside the face. In addition, suture parameter still has the angle of style of suture material, suture, suture, diameter that seam a needle to wait. Nextpage2.
2 suture are statified to composite material rupture the influence suture composite material of tenacity is had admirable fight statified ability, its are statified the form has stretch model (I) and slip model (II) , can part by rupture tenacity (meet an emergency can release rate token) GIC and GIIC express to fight statified ability. Suture composite material ruptures tenacity and relationship of suture craft parameter are close, research discovers [18-24] : (1) suture density and suture diameter are an influence statified rupture two of tenacity main parameter; (2) GIC increases along with suture density and increase, GIIC increases along with suture density and increase to be reduced after that first; (3) when suture density is too low, suture cannot resist statified, crackle expands effectively; (4) exceed some when suture density critical density, on suture inside fiber is injured and cause stress to occupy dominant centrally, bring about statified tenacity is reduced quickly; (5) sutural diameter increased to rise to fight apparently statified expand with crackle ability. Document [23] points out suture raised layer ply between rupture tenacity, GIC suffers the effect of suture material, but with without suture layer board photograph is compared, GIC can raise 10 times above commonly, increase strength of suture density, suture, reduce the Yang model amount of suture, increase the ply of test specimen and axial stiffness, the GIIC that all can raise test specimen is worth. Mattheij [24] used statistical method to study suture distributinging condition and suture craft parameter are right the influence that tenacity ruptures between I layer, the impact that points out suture distributinging condition is very little, control suture tension can obtain best area internal force to learn function. 2.
The influence of the carrying capacity after 3 suture are injured to sufferring concussion considers to make clear, intensity is compressed to rise significantly after ply direction suture makes composite material suffers the carrying capacity after concussion is injured and concussion, the tensile strength after concussion also is improved somewhat, but after extent was not pounded, improvement reduces intensity big [25] . Cheng Xiaoquan [26-28] considers to make clear: Suture did not increase impact in the process statified initial load of injury, but restrained effectively statified of injury patulous, after low speed is pounded statified damaged area is reduced apparently, suture needle is apart from, row spacing and concussion dot and sutural relative position are statified to concussion scathing appearance and size have apparent effect. Suture was restrained local and inflectional happening and patulous, changed those who contain concussion to injure layer board to compress destroy mechanism, the rest after the impact that increased layer board substantially reduces intensity, wait for the change of the element as parameter of lay up material, suture, the CAI that seams plywood is worth the rate that raise to differ, be in commonly 40% above, some is amounted to even 400% . Sankar[29] is in be based on rupture mechanical method forecasts in taking bridge of prefab storied suture to pound next statified and patulous problems in low speed, also discover: Sew can not increase statified and patulous initiative load, but can reduce storied considerably patulous limits. Document [use in 30-31] three-dimensional kinetic finite yuan of law, to the low speed of suture composite material concussion injury undertook numeric imitate, undertook experiment test and verify. The result all makes clear, below action of same blow energy, sew can raise the anti-impact properties of layer board apparently, reduce minute of layer area apparently. Cheng Xiaoquan in document [summary prep above does not have the tensile strength after the research in 32] points out suture layer plywood suffers concussion suture layer plywood, below drawing load action, fiber ruptures and matrix craze is the main factor that brings about a plywood to destroy, and statified injury became minor factor. Suture improved performance of direction of composite material ply, but also cause loss of the fibrous inside the face, reduced the performance inside the face of composite material, accordingly, be necessary to seek on inside the suture technology with fiber small loss. Yasui[33] puts forward to press booked span to decorate pipe on substrate, move back and forth of a yarn bypasses pipe is displayed form, twine with inclined gauze form the 2nd, can make the multiple fabric of different orientaton so. Cross the yarn of ply, introduce with suture through pipe, form three-dimensional structure. Another kind of method is in fundamental frame body strung is used guide the needle decorates complex three-dimensional form, dry yarn is circled guide the needle is twined with different orientaton, the distance that guides the needle is decorated should be controlled pass smoothly in the yarn that can make cross ply. This kind of craft makes beforehand model, fibrous is arranged do not suffer interference when suture, damage of the fiber inside the face is little. 3 Z-pinning enhances technology of composite material Z-pinning is the new technology that 20 centuries enhance a layer one kind when 90 time development rises to combine the strength between composite material layer, this technology draws lessons from the discontinuous suture method in technology of suture composite material [1] , the layer plywood before solidify beforehand direction of dip makings ply is built-in the tigidity weak point such as fiber or metal is marvellous, again solidify forms Z to enhance a plywood. Count the Z-pin of 1%~5% through embedding in direction of layer plywood ply bulk is divided, the intensity inside layer plywood face is only a few degrading, make tenacity ruptures between I layer however of ten times rise, between the layer statified reduce 50%[34] , demonstrative Z-pinning affects lesser circumstance to fell to increase the strength between the layer considerably to the function inside layer plywood face, it is a kind of effective method that enhances the performance between layer plywood layer. The diameter of Z-pin is in commonly 0.
2~1.
Between 0mm, mark of the bulk in layer board is in commonly 1%~5% , material can use a metal (stainless steel, aluminium alloy or titanium alloy) or metalloid (carbon fiber, fibre glass or Kevlar fiber) [35] . The built-in means of Z-pin has two kinds: One kind is odd root embeds [35] , namely one by one embeds Z-pin not in solidify layer plywood, flexibility of this kind of means is strong, can use at curved surface structure to machine, but do not suit large composite material to produce. Another kind is whole embeds (use autoclave and ultrasonic auxiliary and built-in) [4] , be about to a certain number of Z-pin embed at the same time in layer board, efficiency is tall, application is wide. The performance that domestic and international very much scholar studies to Z-pinning enhances composite material makes clear, z-pinning makes the intensity inside layer board face a few degrading, dan Nengming is shown the performance such as intensity is reduced after improving the tenacity between the layer, concussion injure tolerance and concussion [34, 36-41] . Freitas [34] experimented Z-pin is discontinuous to the layer crack tenacity, concussion statified the influence of the function inside knead dough, the result makes clear, count to cent of built-in Z-pin(bulk in layer plywood Z under 5%) and did not add layer of pliable but strong board photograph is compared, z-pin enhances layer board to be able to retain the tensile strength inside 91%~98% face, make tenacity ruptures to raise 18 times between I layer, lessen 50% impact statified injury. M.
Grassi [36] adds pliable but strong to the fiber of Z-fiber of 2% bulk content the stiffness inside the stiffness knead dough of direction of composite material ply undertook study, discover ply direction stiffness raised 22%~35% , and the stiffness inside the face is reduced in 10% less than. Teng Jin [the loss of low speed concussion that 37] increases plywood of composite material layer of pliable but strong to Z-pin undertakes experimenting mixing finite yuan of imitate, the result shows Z-pin adds pliable but strong to make between the layer after concussion statified area area is reduced 50% the left and right sides, in the loss the Z-pin on the foundation of the function inside a few faces makes the stiffness on ply direction rises substantially. Zheng Xitao [the cracking endurance test that 38-39] developed Z-pin to enhance plywood of composite material layer studies and finite yuan of imitate, in document [the individual choice in 38] diameter of 3 kinds of Z-pin and the buildup of 3 kinds of distributinging density means undertook experimenting study, made experiment with the contrast that does not contain the plywood of composite material layer that Z-pin enhances. Consider to make clear: Z-pin raised plywood of composite material layer to rupture considerably tenacity, with do not contain Z-pin structure photograph to compare, meet an emergency can release rate GIC, GIIC to increase 83%~1110% , 23%~438% respectively, below content of identical Z-pin bulk, z-pin distributinging density is mixed to GIC than Z-pin diameter of GIIC rise more businesslike; In document [Z-pin is used to enhance model of bridge couplet force and Z-pin of VCCT law research to enhance I of structure of composite material DCB in 39] model rupture tenacity, use layer of hypostatic and unit imitate to harden compose is mixed nonlinear bedspring yuan imitate Z-pin builds modular computation meet an emergency to be able to be released rate, plywood of layer of composite material of Z-pin of mark of different to score analyse bulk and the I that do not contain Z-pin layer plywood rupture tenacity, research shows Z-pin increased I of plywood of composite material layer significantly model rupture tenacity, and enhance the effect and Z-pin bulk mark closely related, z-pin increased statified and patulous resistance effectively. Fartridge [40] also considered to prove Z-pin through the experiment can very raise a plywood substantially tenacity ruptures between I/II layer. Y.
C.
Gao [41] studies fiber adds pliable but strong of composite material rupture tenacity, put forward to cut lag model, gave out to grow fiber, short staple, strong fiber, weak fibrous divisional standard and the corresponding formula that add pliable but strong, add pliable but strong to containing the fiber of micro-crack process of the mechanism adding pliable but strong of composite material, injury undertook study. The last word is as a result of plywood of composite material layer on ply direction intensity is low with the blemish that fights concussion ability difference, restricted its to develop application, be in especially plane advocate bear the application on force structure. Consequently, enhancing the strength between layer of plywood of composite material layer will be important research task. The method that improves the performance between ply of composite material layer is varied, oversew burgeoningly among them and Z-pinning technology has development latent capacity more, have manufacturing efficiency it is tall, good to enhance the result, finished cost is low advantage, begin oversew and study the sense is great related Z-pinning technology. Enhance the performance between layer of plywood of composite material layer through a few kinds of afore-mentioned methods, will make its apply a domain to expand ceaselessly, but still also put in a few problems to need further research: (1) matrix is added while pliable but strong is raising the tenacity between layer of colophony matrix composite material, also make stiffness and function of damp and hot are reduced, require further research. (2) suture technology is not quite mature still, the tenacity between the layer to suture composite material, concussion injures the suture craft parameter such as diameter of suture density, suture the influence such as tolerance still requires further research, establish can coach design and the technique that produce actually reach technical parameter. Suture introduced larger area internal force to learn performance loss, need to pass pair of suture parameter to undertake optimizing designing, make increasing while cause area internal force to learn function to drop small. (3) the mechanism adding pliable but strong of Z-pinning is still ambiguous, still need to consider to perfect deep further; Need establishs the unified test that evaluates Z-pinning to design parameter each and analytic standard. CNC Milling