Imitate of RTM colophony flow reachs the meaning that its design to the mould

The basis such as Antonelli[23] originallies - fluid mixes theory, build the temperature coupling model that poriferous medium fluid flows, describe colophony accurately thereby the mode of going from place to place when fill. Through these numerical value imitate can discover, viscosity of fibrous permeability, resinous and inject pressure (perhaps note efflux to lead) sound to making technology and design mould are very important. The article applies blame structuralization tetrahedral reseau, union controls aspect / finite yuan (CV/FEM) method, dominate equation according to flow, write computational code, undertake three-dimensional and hypostatic imitate to RTM craft, discuss the effect that its design to the mould. Flow controls equation to be facilitating specification problem, introduce model of flow of three-dimensional and isothermal colophony. In RTM craft, the macroscopical flow process of the fluid can be described well with Darcy equation. Darcy equation can write into the following form [1] : In type, v is the Darcy speed of the fluid, it is the pressure gradient of the fluid, [K] is the permeability tensor that strengthens put oneself in another's position, μ is colophony viscosity. The process of going from place to place of RTM craft is process of surely static state, quality conservation equation can write a form: Such, equation (1) era enters equation (2) get going from place to place dominating equation: Its border condition is: (1) be in in inject mouth, often press the P =P0 when inject, often shed the V=V0 when leading inject; (2) be in in forward position of going from place to place, p=0; (3) be in in mould wall, . Numeric imitate the disperse to dominating equation, use control system commonly / finite yuan (CV/FEM) the method undertakes. The advantage with this kind of the biggest method depends on computation in the process need not of reseau differentiate afresh, big political integrity restricted computational time and reduced computational error. In the course that tracks forward position of going from place to place, express to control aspect with parameter Fi whether by fill or by partial fill. When Fi=1, express to control aspect by complete fill; When Fi=0, control system is done not have completely by fill; When 1>fi>0, express to control body to be in by fill, it is fluid flow forward position here. Pass fill factor, position of forward of going from place to place can come down certainly, the condition of the fill that controls aspect can come down certainly. Fill factor Fi decides by next type: In type, qi(t) controls aspect to flow into this flow always rate, △ Tmin is in all be about to by the time with the least expenditure in the control system of fill, before Fi0 is one fill factor, vi is the bulk that controls aspect. Numeric computation process presses the following measure to undertake: (1) imitate begins, computational unit parameter generates control system model and parameter of relevant control system; (2) charge a pattern in the begining, the control system that assumes inject aperture is in above all one-time be full of, and in fill process, control aspect by the degree of fill will decide according to fill factor; (3) the basis controls equation and attrib border condition, computational node pressure; (4) determine fluid motion rate according to Darcy equation, decide next time condition is chief thereby, each flow forward controls computational colophony inpour the bulk of body, the basis is formulary (4) replace corresponding control system fill factor; (5) to be being repeated newly by fill area measure (3) , (4) , till fill factor is all control system 1.

0, fill process ends. Computational case controls equation and computational measure according to flow, wrote computational program. In this case, use data is black lead fiber / epoxy resin, modular antrum appearance is shown 1 times like the graph, because tetrahedral reseau is right product figure adaptability is very strong, the three-dimensional substance that reflects a fluid sheds a characteristic, reason differentiated in this exemple 474 tetrahedral unit. Case 1: ? Provide dinner for  of  of the Southern Song Dynasty of Nao  predestined relationship receives handkerchief Jun X=ky=kz=1.

2 × 10-8m-2, =0 of colophony viscosity μ .

5Pa · S, constant voltage injects, inject pressure P=0.

1MPa. Flow can discovering in mode of going from place to place is not according to products center semmetry, need attention. Because this is mode of flow of facilitating observation resinous, inject aperture coordinate is (44.

57, 22.

67, 20.

21) , do not be in central part. Whole inject time is very short, have 5 only.

68s. Graph 2 sort movable mould type for the colophony that forecast. The basis pursues 2 knowable, colophony is final the position of fill is a mould all around horny dot, accordingly, the steam vent of the mould can be installed in all around near horny dot. Nextpage 　 is additional, because be in this exemple, assume fiber is in the permeability on each direction is same, be in theoretic, colophony should from inject with globose means Kong Xiangsi week is permeated, it is a circle with respect to expression inside X-Y plane so, by the graph 2 (A) and (B) can see this apparently. Case 2: ? Y=1 of Geng of  of remnant of the  that seek Shen.

2 × 10-8m2, other parameter is changeless. Whole inject time is 9.

57s, if the graph is shown 3 times,the colophony that forecast sorts movable mould type. Parallel case 1 with case 2 can discover, when fiber permeability produces change, not only colophony fill time is changed, colophony flow mode also produced change, colophony flows outwards with ellipsoid face figure. The change of mode of flow of this kind of colophony will affect the design of the mould, especially the appearance of steam vent and decorate, need causes special attention. In this exemple, colophony changes to ellipsoid form flow by globose flow, mould steam vent cannot be decorated in all around horny dot, and should with 2 outside flank is parallel, can design a slit, such gift are nicer ground exhaust, form dry spot likely otherwise or the surface is stomatic. Another parameter about material -- colophony viscosity, through imitate discovery, below the condition that does not change other parameter, viscosity changes resinous fill time only, and to resinous mode of going from place to place does not have an influence. The relation of viscosity and fill time is linear, if pursue,4 are shown. Along with the accretion of viscosity, fill time also increases can linearly; Use lesser viscosity to be able to reduce inject time, but the colophony with too low viscosity is easy spill over from the face distributing a model of the mould, bring about the face that distribute a model to the demand rises or must use complex mould design to spill over in order to prevent resinous. Inject pressure also is time of change resinous fill merely, and type of convection movable mould is affected without what, but with viscosity different depend on its and linear of fill time dispute concerning, if pursue,5 are shown. When pressure is lower, raise inject pressure to be able to reduce fill time significantly, but after reaching fair value, the addition of pressure is right the effect that reduces fill time with respect to decrescent, raised taller requirement to mould intensity, the stuff with need to choose better when the design perhaps is added to mould wall thick, be out of shape in order to resist the attaint of the mould below higher pressure is mixed, accordingly, can the pressure that the basis forecasts - fill time-speed-distance curve optimizes inject pressure, abate the requirement to mould intensity. The place on conclusion put together is narrated, can get the following verdict: (1) the numeric imitate of RTM is very important to mould design, be worth the analysis of imitate result through logarithm, can get a lot of pairs of moulds design very helpful data, design and make of directive mould thereby, the blemish that appears to the likelihood undertakes forecast and be makinged improvement plan. (2) the change of fiber permeability changes fill time not only, and the change that may cause colophony flow mode, changed the eduction way of the gas inside modular antrum, bigger to mould design influence, need gives enough attention. (3) although colophony viscosity won't change resinous flow pattern, but too low to viscosity value colophony needs to use reasonable mould design to prevent its to spill over. (4) inject pressure can change fill time only, won't affect resinous flow pattern, show with fill time nonlinear relation, can optimize inject pressure accordingly, abate the requirement to mould intensity. CNC Milling CNC Machining