Room temperature of C/C composite material and high temperature rupture the test of tenacity and token

　 of Evaluation of 　 of Testing of 　 of Work Of Fracture of 　 of Fracture Toughness of 　 of Keywords 　 C/C Composites although line flexibility ruptures mechanical LEFM acted a very important role in isotropy material [1 ～ 4] , but line flexibility ruptures mechanical the physical process that did not involve material however and critical rupture mechanism. Online flexibility ruptures in mechanical domain, lack the discussion of micromechanism, rupturing because of LEFM lack mechanism, rupture to what fiber enhances composite material consequently the token of tenacity brought huge difficulty and disorder. So composite material ruptures mechanical emerge as the times require [5] . Composite material constant because its are immanent of blemish dimension differ and show rupture differently mode. Be less than some when blemish dimension when critical value, blemish is not patulous, material with total loss mode (General Damage) is destroyed; Be more than some when blemish dimension when critical value, material will expand with crackle mode (Crack Propagation) is destroyed. Composite material crackle is patulous have blame in all linear. As a result of matrix of fibrous intensity outclass and interfacial intensity, encounter fiber and interface when crackle consequently when, often be the interface is destroyed first, and make crackle appears dispersive, turn and expand along interfacial direction. The crackle of anyhow composite material is patulous the process is actual it is compound model patulous process. In addition, composite material ruptures to still be had multiple craze and rupture the characteristic such as the statistical sex of intensity [6] . The method that the person such as Waddoups uses the plasticity area of Irwin to amend coefficient adds scathing area L purely to crack length, the parameter that regards easy processing as KIC and L KIC and L decides with the experiment. The conclusion that the data that they measure according to specific data place will come decide these two parameter and its formula to be accorded with, it is mechanical and OK to put forward line flexibility to rupture apply at composite material, but they did not consider actual crackle is most advanced geometrical figure is very important to composite material [7] . To cast off the limitation that LEFM expands from similar sex crackle, harrison is patulous to the crackle inside crackle plane assumed different energy releases rate Gx, Gy, but the energy that difficulty depends on computational blame expanding from similar sex crackle is released rate, in addition, this kind of method is confined to the application in one-way fiber composite material [8] . Can see, 20 come for years, composite material ruptures mechanical had great progress, clarify and solved large quantities of one problems, but the research that still wants deeper to composite material arrangement and understanding. Because lack the experimental data that can trust, up to now most composite material ruptures mechanical model still builds the base in hypothesis over. As a result of the diversity of C/C composite material and complexity, often make theoretical calculation encounters huge difficulty, cannot solve even sometimes. Below this kind of circumstance, test method makes the main instrument that solves a problem, want to rupture in C/C composite material at the same time tenacity respect gains headway further, also hang on experiment provides scientific basis. In show level in, the advantage such as because test technology is fast the versatility of development and experiment method, intuitionistic sex and imitate sex, make check a technology to become without commutable powerful tool. Composite material of 1 　 C/C ruptures the test of tenacity ruptures about C/C composite material at present Shangbuduo sees the paper data of tenacity respect, can from a few value of KIC of composite material of C/C of part of the understanding in document, see a table 1 [9 ～ 13] . From the watch 1 in can see, KIC of C/C composite material and the composition that enhance body carbon fiber and shop become ordinal, direction to wait have huge concern; Next also with ply of breach of test method, sample size, A/w(and sample ply than) all sorts of elements such as rate of value, to load and temperature have cannot intersected connection. The Fracture Toughness KIC Of Many Kinds Of C/C Composites of 　 of KIC value Table 1 that expresses all sorts of 1 C/C composite material is phyletic C/C3DC/CKIC/(MPa of cloth of carbon of C/C of orthogonality of one-way C/C of C/C of felt of black lead carbon. M1/2)0.

751.

754.

04.

57.

0 ± 14.

5 ～ 8.

0 　 　 (concentration percentage by volume of 1) carbon fiber compares an element. From the watch 1 knowable, the KIC of pure black lead has 0 only only.

75MPa*m1/2, far under KIC of other C/C composite material, from this knowable, the impact that 100 minutes of content of the carbon fiber in C/C composite material are worth to KIC is bigger. Generally speaking, c/C composite material is in shape in production process, because heat up what prestressing force arises beforehand crackle is by certain span normally in matrix perpendicular at carbon fiber [14] , because matrix carbon is containing leftover stress,fall to cause crackle easily to be broken prematurely again firm patulous, the critical KIC that compares actual matrix carbon is small much, bring about C/C composite material thereby initiative crackle expands KIC is worth inferior; When crackle patulous way disperses and when transferring Yu Ping to expand at fiber direction all right, carbon fiber bridge is received reach pull out begin to act well, consequently the KIC of C/C composite material appears ascendant trend, when because this can say carbon fiber concentration percentage by volume is than content inside certain limits,increasing, value of KIC of C/C composite material also lifts subsequently, but the critical cost that compares about concentration percentage by volume still has no a report up to now, remain to study deep. (2) fibrous composition and shop become means factor. The composition of carbon fiber and the influence law that the shop becomes means to be worth to KIC of C/C composite material still remain to study deep, but have notable at 2 o'clock: 1) arranges the bridge of disorder carbon fiber to receive action to expand particular stress bears in the process in crackle, released the one part stress with most advanced crackle thereby, raised KIC cost; 2)C/C composite material causes shear failure easily as a result of weak interfacial intensity, reduced KIC cost thereby. (3) interface element. The data shows [13] , structure of POG of C/C composite material is helpful for the addition of tenacity of C/C composite material, and TOG structure is not old to the contribution of tenacity of C/C composite material. Proper interfacial bonding strength adds composite material of C/C of pliable but strong effectively, its are true the reason depends on an interface can passivation crackle is most advanced and apparent change crackle is patulous way, and can control carbon fiber pull out and the bridge is received. (Element of 4) graphitization system. The graphitization of C/C composite material handles what increase C/C composite material effectively to rupture tenacity [15] . Processing of graphitization of C/C composite material increased micro-crack, the structural form that also changed crackle at the same time [16, 17] , also reduced C/C composite material so the sensitivity to breach and the way that changed crackle to expand, thereby these changes and the micro-crack network structure after increasing had a more effective energy dissipation mechanism, controlled C/C composite material thereby rupture process [16] . (Factor of rate of 5) to load. To load rate is right inside certain limits the impact that KIC of C/C composite material is worth is bigger [18] , what basically affecting critical crackle at to load rate is patulous and the plasticity below high temperature condition is out of shape rate [19] . Document [20] studied to load rate is right metallic radical composite material ruptures the influence that tenacity KIC is worth, be more than 1m/s when to load rate only when, composite material KIC just begins to increase subsequently, its reason depends on high to load rate can forcing a few micro-crack to answer and form great flaw without time, composite material crackle is most advanced at the same time destroy produce an area to increase along with the addition of to load rate, bring about composite material to arise thereby bigger be out of shape. (6)a/w is worth an element. The data shows [11] , value of KIC of orthogonal C/C composite material increases along with A/w value and increase, and 3D C/C composite material is not changed along with what A/w is worth however and change [13] , remain to study further about this respect. (7) temperature element. What KIC of C/C composite material basically follows temperature is elevatory and elevatory [9, 21] , but it is to composite material of short staple C/C when 1400 ℃ , KIC value has a bit to be reduced smally, somebody [9] the change of the anisotropy of the hot coefficient of expansion that the explanation leaves the reaction between interfacial layer and area of fiber matrix interface for high temperature condition affected fibrous to pull out mechanism. (8) breach element. The KIC cost that sample of hill glyph breach tests rises along with temperature and rise somewhat, but sample of breach of straight edge form keeps basically however changeless [21] , and hill glyph sample has before achieving critical crackle to expand critical crackle is patulous, bring about value of KIC of C/C composite material to have a small addition thereby [22] . Breach orientaton is right also the impact of KIC is bigger, the KIC when the Z Xiang Ping of breach direction and 3D C/C composite material goes relatively the KIC when going with X Xiang Ping is big. In addition, sample width, surface is bright and clean degree and all sorts of elements such as side effect all can rupture to C/C composite material the test of tenacity produces an effect [23] , the report that concerns this respect does not see more. Crackle of C/C composite material is most advanced can receive as a result of fiber bridge, fiber pulls out and the destruction with change direction to wait for action and be formed crackle branch, certain produces a division (Process Zone) . Once crackle of C/C composite material begins to expand, its are most advanced can form destroy produce a division, destroy those who produce a division to form can reduce crackle intensity of field of most advanced stress, want crackle continues to expand, must raise adscititious stress again, destroy those who produce a division to form namely increased crackle patulous obstruction [24] ; Next, because be being destroyed,produce trifling there are tiny flaw and gap inside region, its measure often with macroscopical crackle (or breach) with quantitative class, tall even one class, because this destroys the existence that produces a division to may change crackle completely (or breach) the stress around changes the character of field, mechanical to rupturing adverse [25] . Accordingly, simple KIC value already cannot reflect patulous ability of crackle of resistance of C/C composite material thoroughly. Current, more popular use crackle to grow obstruction R curve to come to those who depict C/C composite material rupture tenacity, but the research of curve of R of concerned C/C composite material still is in puerile phase, concerned data is little and dispersive sex is big, because this should begin the test of curve of R of C/C composite material and research energetically. The room temperature load from C/C composite material - displacement curve can see, although be in,under crackle the load of initiative and patulous phase falls, c/C composite material also arose certain nonlinear feature, this shows crackle is most advanced and patulous previously, in microcosmic rupture the micro-crack in there still is matrix of a few elephants in the process, interface is taken off stick and the phenomenon such as slippage; These can send quiver to obtain test and verify from sound [26] . Next, c/C composite material is in high temperature (1600 ℃ ) when, have the feature such as aggrandizement of high strenth, deformation and certain plasticity [27] , rupture because of what this measures C/C composite material tenacity cannot rely on KIC and R curve to describe merely, and should written guarantee syncretic is planted the description is nonlinear diagnostic parameter will try to complement. Among them work to break is a kind most the method of effective. Although work to break is not parameter of a kind of material, but it uses token extensively already complex rupture the crackle of the process grows resistance. Composite material of 2 　 C/C ruptures the composite material of token 　 C/C of tenacity ruptures the token method of tenacity is very much, basically have way of stress intensity factor, energy standard standard, j integration method and law of work to break. Have document [28, 29] make clear, use what J integration method tests C/C composite material to rupture tenacity does not have an advantage but character, the reason depends on C/C composite material be in under limits of 2200 ℃ temperature inside, its are mechanical function satisfies line flexibility requirement basically, northwest industry university uses composite material of C/C of Wu Kelan high temperature the 3D that device of mechanical function test checks is fine the drawing function that fabricates C/C composite material proved afore-mentioned viewpoints. Bent at 3 o'clock (SENB) planar meet an emergency ruptures the test of tenacity because its inherent advantage early is labelled by association of American material trial standard namely ASTM E399-90 [30] . Rupture to composite material of the C/C below high temperature condition for the conditional limitation that tenacity checks and practical and simple sex, most country uses SENB to rupture as test C/C composite material more a kind of of tenacity powerful tool. Accordingly a lot of scholars gave a lot of KIC expression after improving in the light of derivation of law of composite material SENB. It is X and I to breach orientaton to 2DC/C composite material, its KIC expression is: KIC= [Pmax/(B*W1/2) ] . YY is correction factor [31, 32] . It is X and Z to breach orientaton to 2D C/C composite material, the expression of its KIC is: KIC= σ (A)1/2. The F(a/w) with specific F(a/w) is in document [33] in have expatiatory. It is Z to breach orientaton to plywood of layer of orthogonal C/C composite material, the expression of its KIC is: KIC=3PC/2BW2. (π A)1/2. 　 of 　 of F(a/w) 　 　 F(a/w)=1.

09-1.

735(a/w)+8.

20(a/w)2-14.

18(a/w)3+14.

57(a/w)4 　 is X and Z to breach orientaton to 3D C/C composite material, the expression of its KIC is: KIC=(P. S)/B. W1/2) . 　 of 　 of F(a/w) 　 　 F(a/w)=2.

9(a/w)1/2-4.

6(a/w)3/2+21.

8(a/w)5/2-37.

6(a/w)7/2+38.

The blame that 7(a/w)9/2 　 expands as a result of composite material crackle from similar sex characteristic, crackle expands orientaton is opposite rupture the test of tenacity is crucial, because afore-mentioned this KIC expression can be used at the C/C composite material with specific some only, and be in puerile phase, need is perfected further and still develop. The test method of factor of intensity of stress of C/C composite material has flexibility law, reseau law, light to play law, laser holographic law and laser come loose spot law, measure stress intensity factor with flexibility law, but have the aid of ruptures at the test the instrument equipment of tenacity, to planar problem it is simpler and practical, but still need to solve two main problems: The influence of 1) breach ply and factor of strength of length correspondence strength; How does 2) decide factor of intensity of initiative crackle stress. Say material is in normally rupture in destroying a process, because transmission expands and form new unit face of crackle to accumulate requires energy to be work to break, can get through following formula [34 ～ 35] : γ WOF=U/2AU is rupture can; A expresses an area to rupture. And rupture can usable and following formula gets U [36] : U=A. Vch/Vc. P/10A is the area that place of load time-speed-distance curve includes; Vch is to load rate; Vc is recorder rate; P is value of full scale of material experiment machine. Express the costs of 2 work to break that collected all sorts of material with carbon element, can see from which, c/C composite material is purer the tower above of work to break of graphite material 1 ～ 2 amounts class. The γ  WOF that expresses all sorts of 2 C/C composite material is worth WOF/(J*m-2)80363 of  of γ of C/C of cloth of carbon of one-way C/C3DC/C of C/C of felt of carbon of black lead of WOF Of Many Kinds Of C/C Composites of  of γ of Work-of Fracture of Table 2 　 .

545005472.

56000 　 above all, express quite 1 with the watch 2 results can see, work to break also the ability that correctly token gives C/C composite material to resist crackle expands. The work to break of the layer plywood that C/C composite material enhances with carbolic cloth and 3D C/C composite material is the biggest, this and same C/C composite material rupture tenacity is corresponding and consistent. Next, γ  WOF can mirror a structure of interface of C/C composite material more sensitively to rupture to C/C composite material the influence of tenacity. Somebody uses magnetic field to handle matrix of intermediate photograph bitumen, make this is planted matrix layer piece perpendicular at carbon fiber [37] , the experiment shows magnetic field of this kind of classics is treated the work to break that the work to break of C/C composite material compares the C/C composite material that handles without magnetic field (4500J/m2) is gotten greatly much, achieve 9500J/m2 [38] , its reason depends on fibrous pulling out, fibrous ruptures, fibrous bridge is received, the interface is taken off stick, slippage and crackle branch, change direction to to work to break huge is contributed. This shows work to break to C/C composite material rupture the test of tenacity has extremely powerful auxiliary token effect. Work to break can assist token parameter as a kind only, basically depending on it is not constant of a kind of material, the effect that suffers the element such as sample size and test method is bigger. (Element of 1) breach type. Value of work to break depends on rupture exterior accumulating, for the experiment simplify and the feasibility of the operation, people is ordinary with perpendicular rupture as name at a plane of sample underside exterior accumulating, and of the experiment rupture the surface is curved surface of a labyrinthian cobbly; After simplifying to reduce this to plant as far as possible and the systematic error that cause, because this often uses straight edge form and sample of hill glyph breach. (Factor of rate of 2) to load. The experiment makes clear, be in when to load rate below room temperature condition 10 ～ 0.

When 5mm/min, obtain stable load time-speed-distance curve impossibly, be less than in to load rate only 0.

The ability when 1mm/min gets stable load time-speed-distance curve, generally speaking, use 0.

05mm/min. (3)a/w element. Somebody studied A/w is right the influence of work to break, discover the addition as A/w, work to break is worth drop off, investigate its reason basically depends on C/C composite material rupture destroy mode to change along with the change of A/w, bring about the fall of value of work to break thereby. (4) is crossed compare an element high. At 3 o'clock in bend test, cross high ratio to be opposite of C/C composite material rupture mode has very big effect, the data shows, should cross compare ≥ high 10 when, c/C composite material just is in pull crush bad mode, and be in all sorts of rupturing the difference of work to break of the C/C composite material that measures below mode is very big. Accordingly, work to break can be planted in this only specific conditional dirty assists a method for. 3 conclusion rupture as a result of line flexibility mechanical and inherent characteristic, and the diversity of C/C composite material and complexity, make C/C composite material ruptures the test of tenacity and token get the influence of all sorts of outside elements. Current, the mechanical function of composite material of C/C of world each country, rupture tenacity test and token are quite confused still, on one hand, annual and many emerge in large numbers gives all sorts of data of C/C composite material; On the other hand, lose as a result of the standard with these data uniform neither one can compare a gender, appear even contradictory, make production and design personnel cannot be used, brought huge pecuniary loss so, restricted the development of C/C composite material badly. Because this is pressing,standardization undertakes to its on the base that needs to building C/C composite material to test a level, make all sorts of data of C/C composite material are had can compare gender and accuracy, promote the development of C/C composite material then, lay next foundations to build a perfect C/C composite material to test a level in the future, also rupture for other composite material the test of tenacity, token provides referenced basis. CNC Milling CNC Machining