CN102390121A - Temperature compensation method for composite material workpiece autoclave forming workpiece - Google Patents

Abstract

The invention discloses a temperature compensation method for a composite material workpiece autoclave forming workpiece, which utilizes heaters for heating the low-temperature parts of the workpiece to realize temperature compensation and includes steps: simplifying an autoclave model, conducting meshing and simulating the workpiece temperature field in the forming process of the composite material workpiece autoclave by temperature field simulation software; determining the positions of maximum temperature value point and each minimum temperature value point; determining the number and the positions of the heaters; determining the temperature difference value between the maximum temperature value point and each minimum temperature value point; determining the function of heat release rate of each heater; introducing the function of heat release rate of each heater into a three-dimensional heat conduction equation, and conducting analog computation, thus obtaining the optimized temperature field; if the optimized temperature field still can not meet requirements, repeating the last steps until the temperature field of the workpiece meets the requirements. The method can control the temperature difference of the workpiece, ensure the uniformity of the temperature field and lower the production cost.

Description

Composite product autoclave molding product temperature compensation

Technical field

The invention belongs to composite autoclave molding technical field, particularly composite autoclave molding process product temperature compensation.

Background technology

Carbon fiber enhancement resin base composite material because of its high specific strength, high specific stiffness, corrosion-resistant, advantage such as can design, obtained the extensive use of aircraft industry, its consumption has become one of advanced sign of aircraft.At present, the domestic air mail corporate boss will adopt autoclave forming process to make composite element.In composite product autoclave molding process, the uniformity in product temperature field there is very high requirement, the product excessive temperature differentials can cause composite product to solidify a series of problems such as inhomogeneous, product distortion.Present stage guarantees that the uniform main method in temperature field is to reduce heating rate, sets up the insulation platform, reduces the temperature difference with this.But this method has reduced production efficiency, has increased production cost, needs very strong experience to instruct, and for those baroque frocks, often can not satisfy production requirement; In addition, can be through tool structure being optimized the temperature difference of controlling product, but for the frock of structure more complicated; The heating rate of some position of product is still very low; Cause the temperature of this position lower, the product temperature difference is big, and results of optimization can not satisfy production requirement.

Therefore, the inventor furthers investigate to present deficiency in the composite product forming process, and through repeatedly improving, this case produces thus.

Summary of the invention

Technical problem to be solved by this invention is to defective and deficiency in the aforementioned background art, and a kind of composite product autoclave molding product temperature compensation is provided, and it can control the temperature difference of product, guarantees the uniformity in temperature field, reduces production costs.

The present invention is for solving above technical problem, and the technical scheme that is adopted is:

A kind of composite product autoclave molding product temperature compensation utilizes heater that the lower position of product temperature is heated, and realizes temperature-compensating.

The said temperature compensation method comprises the steps:

(1) the autoclave model is simplified, divided grid, through product temperature field in the temperature field simulation software simulation composite product autoclave molding process;

(2) confirm the position of temperature maximum of points and the position of each temperature minimum point according to the temperature field of simulation;

(3) definite number and position that needs the heater of installation;

(4) confirm the temperature maximum of points each constantly with the temperature gap of each temperature minimum point;

(5) confirm the rate of heat release function of each heater;

(6) the rate of heat release function of each heater is introduced the three-dimensional equation of heat conduction, carry out analog computation, the temperature field after being optimized;

(7) if the temperature field of optimizing does not still meet the demands, repeating step (1)～step (5) meets the demands until the product temperature field.

In the above-mentioned steps (1), the step that adopts HyperMesh to carry out the grid division is:

(11) from CATIA, derive the geometrical model of frock, product and autoclave, import among the HyperMesh then;

(12) carry out the geometry cleaning, integrate broken, remove little rounded corner, suppress unwanted line etc.;

(13) divide grid, earlier with the frock subregion, with the shape with the frock contact-making surface that supports the frock lower surface is carried out subregion, behind the subregion, the frock lower surface is divided into a plurality of grids, and the zone between each grid is exactly the cross sectional shape that supports; Frock face behind the subregion is divided two-dimensional grid; Two-dimensional grid with each grid is drawn into the entity grid then; The height of the height that stretches for supporting, the entity grid is divided in the space between the entity grid that will be drawn into by the grid two-dimensional grid, just obtains the entity grid that supports;

(14) upwards the squint distance of a frock thickness of frock lower surface two-dimensional grid is obtained the frock three-dimensional grid, more upwards the squint distance of a product thickness of frock upper surface grid is just obtained the three-dimensional grid of product;

(15) last, each face that the grid of having divided is stretched to autoclave has just been accomplished the division of grid in the autoclave zone.

In the above-mentioned steps (2), confirm that the method for temperature maximum of points and temperature minimum point is: confirm the moment that the temperature difference is maximum according to the product thermoisopleth cloud atlas of simulation, confirm the thermoisopleth position of this moment temperature maximum of points and the thermoisopleth position of temperature minimum point; And the position of each minimum point numbered i=1; 2,3 ... N, N are the numbers of temperature minimum point.

In the above-mentioned steps (3), the number of heater is identical with the number of temperature minimum point, and heater is installed in the back of the pairing frock in temperature minimum point position described in the step (2), fit with the frock back surfaces.

The content of above-mentioned steps (4) is: the function that all positions of confirming in the abovementioned steps (2) is become " temperature-time " at the temperature value piecewise fitting of each moment point; And the maximum temperature function deducted each minimum temperature funtion, obtain the difference T of each minimum temperature and maximum temperature _Cha(t) _i, i=1,2,3 ..., N, wherein N is the number of temperature minimum point, i is the numbering of temperature minimum point.

Confirm rate of heat release function A in the above-mentioned steps (5) _i(t) expression formula is:

${\mathrm{<figure-callout\; id="1"\; label="C\; p"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">C</figure-callout>}}_p{\mathrm{\&rho;}}_1(T_{\mathrm{cha}}{\left(t\right)}_i{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+\frac{A_i\left(t\right)h_i{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2}{{\mathrm{\&lambda;}}_2}{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+\frac{A_i\left(t\right)h_i{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1}{{\mathrm{\&lambda;}}_1}\frac{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1}{2})+{\mathrm{<figure-callout\; id="2"\; label="C\; p"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">C</figure-callout>}}_p{\mathrm{\&rho;}}_2(T_{\mathrm{cha}}{\left(t\right)}_i{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+\frac{A_i\left(t\right){\mathrm{<figure-callout\; id="2"\; label="h\; i\; b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">h</figure-callout>}}_i{b}_{}{}_2}{{\mathrm{\&lambda;}}_2}\frac{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2}{2})$

$=h_i{\&Integral;}_{t_0}^t{A}_i\left(t\right)\mathrm{dt}$

Wherein, C _P1, C _P2Be respectively the specific heat of frock and product, ρ ₁, ρ ₂Be respectively the density of frock and product, T _Cha(t) _iBe frock upper surface temperature minimum point position t poor with maximum temperature constantly when not adding heater, b ₁, b ₂Be respectively the thickness of tool mold and product, h _iBe the thickness of i heater, λ ₁, λ ₂It is respectively the thermal conductivity factor of frock and product material.

The content of above-mentioned steps (6) is: autoclave, frock, product are carried out grid divide; Heater area is arranged to subdomain thermal source item; According to the rate of heat release function that solves in the step (5); Through being programmed in the rate of heat release that heater area is set in the temperature field simulation software, the rate of heat release function is introduced the three-dimensional equation of heat conduction, the product temperature field after simulation is optimized.

After adopting such scheme, the present invention heats product temperature lower position through utilizing heater, makes the heating rate of this position and temperature higher point close, guarantees the even of product temperature field.In temperature field with finite element method for simulating composite product autoclave molding process; Can on the basis of existing simulation, utilize the method that adds heater compensation heating the uniformity in temperature field is controlled and to be optimized, for reducing the temperature difference, improving the product Forming Quality a kind of practicable method is provided; And the utilization of this method can reduce real cost of production, enhances productivity.

Description of drawings

Fig. 1 is a flow chart of the present invention;

Fig. 2 is the relative position relation sketch map of heater among the present invention, frock, product.

The specific embodiment

Below will combine accompanying drawing, technical scheme of the present invention will be elaborated.

The present invention provides a kind of composite product autoclave molding product temperature compensation, mainly is to utilize heater that the lower position of product temperature is heated, thereby realizes temperature-compensating.

Cooperating shown in Figure 1ly, is concrete implementation procedure of the present invention, and step is:

(1) according to the structure and the operation logic of autoclave the autoclave model is simplified, then according to curing process, atmospheric density, viscosity, thermal conductivity factor, pressure, wind speed in the definition autoclave; The rate of heat release function that the density of frock, product, specific heat capacity, thermal conductivity factor and product solidify carries out the temperature field through temperature field simulation software and calculates, and obtains each temperature constantly of each location point of product;

(2) confirm the position of temperature maximum of points and the position of each temperature minimum point according to the temperature field of simulation;

During concrete the realization, can confirm the moment that the temperature difference is maximum, confirm the thermoisopleth position of this moment temperature maximum of points and the thermoisopleth position of temperature minimum point according to the product thermoisopleth cloud atlas of simulation; And the position of each minimum point numbered i=1,2; 3;, N, N are the numbers of temperature minimum point.

(3) definite number and position that needs the heater of installation; Specifically be that the number of heater is identical with the number of temperature minimum point; Have promptly what temperature minimums are point; Just add what heaters, and heater is installed in the back of the pairing frock in temperature minimum point position described in the step (2), fit with the frock back surfaces;

(4) confirm the temperature maximum of points each constantly with the temperature gap of each temperature minimum point; It specifically is the function that all positions of confirming in the abovementioned steps (2) is become " temperature-time " at the temperature value piecewise fitting of each moment point; The thermometer that is about to each position is shown as the function of time; And the temperature max function deducted each temperature minimum function, obtain the peaked difference T of each temperature minimum and temperature _Cha(t) _i, i=1,2,3 ..., N, N are the numbers of temperature minimum point, i is the numbering of temperature minimum point;

(5) confirm the rate of heat release function of each heater,, obtain finding the solution each heater rate of heat release function A in view of the above owing to be heated the temperature that the temperature of position is substantially equal to temperature higher point position _i(t) concrete steps are:

(51) the rate of heat release function of heater is the function of time, and it is expressed as A _i(t) (the w/m of unit ³), be A at dt time liberated heat _i(t) dtV _i, i=1 wherein, 2,3 ..., N, i represent the numbering of heater, and be corresponding with the numbering of temperature minimum point, V _iThe volume of representing i heater, in like manner, the physical quantity of the following i of being designated as that occurs is below all represented the related physical quantity corresponding to i heater.Suppose that the radiator liberated heat can pass to product through frock very soon.

(52) consideration heater liberated heat is propagated on the frock thickness direction, and then heat flow density can be expressed as formula (1):

$q_i=\frac{A_i\left(t\right)\mathrm{dtV}}{S_i\mathrm{dt}}=\frac{A_i\left(t\right)V_i}{S_i}---\left(1\right)$

S wherein _iBe heater overlaps face with frock area, S _iEqual the area that the temperature minimum thermoisopleth surrounds, so have:

V _i＝S _i□h _i (2)

H wherein _iBe the thickness of i heater;

(53) can the thermograde that produce owing to the heat release of heater on the tool mold thickness direction be used as uniformly, promptly

$\frac{\&PartialD;T}{\&PartialD;x}=\frac{\mathrm{\&Delta;}{T}_{i1}}{b_1}---\left(3\right)$

Wherein, Δ T _I1Be the temperature difference of tool mold upper and lower surfaces, b ₁Be the thickness of tool mold;

(54) in like manner, the thermograde of product on thickness direction is following relational expression:

$\frac{\&PartialD;T}{\&PartialD;x}=\frac{\mathrm{\&Delta;}{T}_{i2}}{b_2}---\left(4\right)$

Δ T _I2Be temperature minimum position product lower surface and the temperature difference that deducts upper surface, b ₂Be the thickness of product;

Have according to the thermal conduction study formula:

$q_i=\frac{A_i\left(t\right)V_i}{S_i}=\frac{\mathrm{\&Delta;}{T}_i}{\frac{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1}{{\mathrm{\&lambda;}}_1}+\frac{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2}{{\mathrm{\&lambda;}}_2}}=\frac{\mathrm{\&Delta;}{T}_{i1}}{\frac{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1}{{\mathrm{\&lambda;}}_1}}=\frac{\mathrm{\&Delta;}{T}_{i2}}{\frac{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2}{{\mathrm{\&lambda;}}_2}}---\left(5\right)$

Wherein, q _iBe heat flow density, λ ₁, λ ₂It is respectively the thermal conductivity factor of frock and product material; Δ T _iBe the tool mold lower surface and the temperature difference of product upper surface on same position.

(55) purpose of heater is the product regional temperature to be carried out the compensation of heat than low spot; Make its temperature near higher temperature, because product thickness is little, when derivation rate of heat release function; Main consideration reduces the product upper surface temperature difference; And the compensation heat is to pass to upper surface from the product lower surface, if upper surface obtains heat compensation, the temperature field uniformity in whole product zone also can improve.In order to compensate product upper surface high and low temperature temperature difference T between the two _Cha(t) _i, promptly heater makes product upper surface temperature minimum position temperature rising T _Cha(t) _i, guarantee the uniformity of both heating rates.

The heat release of heater makes product upper surface temperature than the low point temperature T that raise _Cha(t) _i, so, according to formula (4), temperature raises and is on the thickness of this position one deck:

X is the vertical range with the product upper surface.

Can obtain thus because the temperature that heater heat release product lower surface raises is: T _Cha(t) _i+ Δ T _I2

Because frock upper surface temperature overlaps with the product lower surface, suppose that both temperature equate that the temperature of certain one deck rises on the tool mold so:

Y is the vertical range with the tool mold upper surface.

(56) can obtain thus because the heat release of heater makes the heat of tool mold and product absorption be:

(8)

Wherein, C wherein _P1, C _P2Be respectively the specific heat of frock and product, ρ ₁, ρ ₂Be respectively the density of frock and product, S _iIt is the heat transfer area that heater contacts with tool mold.

(57) the heater liberated heat is all absorbed by tool mold and product, so just has:

${\mathrm{<figure-callout\; id="1"\; label="C\; p"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">C</figure-callout>}}_p{\mathrm{\&rho;}}_1{S}_i(T_{\mathrm{cha}}{\left(t\right)}_i{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+\mathrm{\&Delta;}{T}_{i2}{b}_2+\mathrm{\&Delta;}{T}_{i1}\frac{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1}{2})+{\mathrm{<figure-callout\; id="2"\; label="C\; p"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">C</figure-callout>}}_p{\mathrm{\&rho;}}_2{S}_i(T_{\mathrm{cha}}{\left(t\right)}_i{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+\mathrm{\&Delta;}{T}_{i2}\frac{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2}{2})$ (9)

$=V_i{\&Integral;}_{t_0}^t{A}_i\left(t\right)\mathrm{dt}$

t ₀It is the value zero hour of each temperature rise period on the process curve;

(58) can obtain according to formula (5):

$\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="T\; i"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">T</figure-callout>}}_i=\frac{A_i\left(t\right)V_i{b}_1}{S_i{\mathrm{\&lambda;}}_1}---\left(10\right)$

$\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="T\; i"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">T</figure-callout>}}_i=\frac{A_i\left(t\right)V_i{b}_2}{S_i{\mathrm{\&lambda;}}_2}---\left(11\right)$

(59) bring formula (10), (11) into formula (9), just obtain about A _i(t) equation.

${\mathrm{<figure-callout\; id="1"\; label="C\; p"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">C</figure-callout>}}_p{\mathrm{\&rho;}}_1(T_{\mathrm{cha}}{\left(t\right)}_i{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+\frac{A_i\left(t\right)h_{\mathrm{<figure-callout\; id="2"\; label="i\; b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">i</figure-callout>}}{b}_{}{}_2}{{\mathrm{\&lambda;}}_2}{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+\frac{A_i\left(t\right)h_{\mathrm{<figure-callout\; id="1"\; label="i\; b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">i</figure-callout>}}{b}_{}{}_1}{{\mathrm{\&lambda;}}_1}\frac{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1}{2})+{\mathrm{<figure-callout\; id="2"\; label="C\; p"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">C</figure-callout>}}_p{\mathrm{\&rho;}}_2(T_{\mathrm{cha}}{\left(t\right)}_i{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+\frac{A_i\left(t\right)h_{\mathrm{<figure-callout\; id="2"\; label="i\; b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">i</figure-callout>}}{b}_{}{}_2}{{\mathrm{\&lambda;}}_2}\frac{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">b</figure-callout>}}_2}{2})---\left(12\right)$

$=h_i{\&Integral;}_{t_0}^t{A}_i\left(t\right)\mathrm{dt}$

Obtain about A _i(t) the differential equation obtains about A through separating the above-mentioned differential equation _i(t) expression formula, in the autoclave molding process, product each point temperature roughly is the linear function of time, in view of the above, the rate of heat release of the heater that draws can according to rate of heat release, be selected the heater of appropriate power for a constant value.

(6) autoclave, frock, product are carried out grid and divide, heater area is arranged to subdomain thermal source item, according to the rate of heat release function A that solves in the step (5) _i(t),, the rate of heat release function is introduced the three-dimensional equation of heat conduction, the product temperature field after simulation is optimized through being programmed in the rate of heat release that heater area is set in the temperature field simulation software;

(7) obtain adding the temperature field of product behind the heater through analog computation, then stop to calculate if the temperature field uniformity meets the demands; If also do not meet the demands, then the production demand is satisfied until the product temperature field in repeating step (1)～(6) on the basis of present stage;

(8) in process of production; Position, number, the rate of heat release function of the heater that draws according to simulation are arranged heater; Heater is attached to the frock back, and power supply lead wire can be drawn with the circuit of thermocouple, and heater model as used herein does not have specific (special) requirements; For the ease of installing, can adopt the heater about thickness 1.5mm on the market.

Below will combine instantiation that technical scheme provided by the present invention is described.

During enforcement, according to the structure and the operation logic of autoclave the autoclave model is simplified, the utilization grid is divided software, like HyperMesh, grid is divided in The whole calculations such as autoclave, frock, product zone.The concrete steps that adopt the HyperMesh grid to divide are:

(a) from CATIA, derive the geometrical model of frock, product and autoclave, import among the HyperMesh then;

(b) carry out the geometry cleaning, integrate broken, remove little rounded corner, suppress unwanted line etc.;

(c) divide grid, earlier with the frock subregion, with the shape with the frock contact-making surface that supports the frock lower surface is carried out subregion, behind the subregion, the frock lower surface is divided into a plurality of grids, and the zone between each grid is exactly the cross sectional shape that supports; Frock face behind the subregion is divided two-dimensional grid; Two-dimensional grid with each grid is drawn into the entity grid then; The height of the height that stretches for supporting, the entity grid is divided in the space between the entity grid that will be drawn into by the grid two-dimensional grid, just obtains the entity grid that supports;

(d) upwards the squint distance of a frock thickness of frock lower surface two-dimensional grid is obtained the frock three-dimensional grid, more upwards the squint distance of a product thickness of frock upper surface grid is just obtained the three-dimensional grid of product;

(e) last, each face that the grid of having divided is stretched to autoclave has just been accomplished the division of grid in the autoclave zone.

With importing to temperature field simulation software after the grid derivation after dividing, in Fluent, in temperature field simulation software, in solver, being provided with and finding the solution type is unsteady Model; Material properties is set, according to curing process, the setting of the various technological parameters of promptly under the actual conditions autoclave being done; Comprise atmosphere temperature rising speed, pressure etc. in jar, air is the ideal body of can not calming the anger in the definition autoclave; Characteristic such as viscosity, thermal conductivity factor is a default setting, and characteristics such as the density of frock, product, specific heat capacity, thermal conductivity factor are filled in according to the actual nature of product and frock, in this experiment; The frock material is an aluminium, and product density is 1632Kg/m ³, specific heat capacity is 837.2J/ (Kg K), thermal conductivity factor is 0.3w/ (m K); It is five atmospheric pressure that pressure is set in operating environment; Boundary condition is provided with, and wind speed is set to 4m/s, through programming, makes hot blast temperature consistent with the curing process curve, and the boundary condition of outmost that wall of autoclave is arranged to adiabatic boundary condition, and the boundary condition of all the other walls is arranged to coupled boundary condition; The heat release function that product solidifies is set, and the heat release function is following:

$\stackrel{\&CenterDot;}{q}={\mathrm{\&rho;}}_r{H}_r\frac{d\&PartialD;}{\mathrm{dt}}={\mathrm{\&rho;}}_r{H}_r{A}_1\&times;{\exp }^{\frac{-{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">E</figure-callout>}}_1}{\mathrm{RT}}}\&times;{({\&PartialD;}_{\max }-\&PartialD;)}^l+A_2\&times;{\exp }^{\frac{-{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">E</figure-callout>}}_2}{\mathrm{RT}}}\&times;{({\&PartialD;}_{\max }-\&PartialD;)}^n\&times;{\&PartialD;}^m$

$\frac{d\&PartialD;}{\mathrm{dt}}=A_1\&times;{\exp }^{\frac{-{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">E</figure-callout>}}_1}{\mathrm{RT}}}\&times;{({\&PartialD;}_{\max }-\&PartialD;)}^l+A_2\&times;{\exp }^{\frac{-{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA0000099936540000021.png"\; state="\{\{state\}\}">E</figure-callout>}}_2}{\mathrm{RT}}}\&times;{({\&PartialD;}_{\max }-\&PartialD;)}^n\&times;{\&PartialD;}^m$

Liberated heat when being resin solidification, ρ in the formula _rBe resin density, H _rThe total amount of heat that the unit mass resin is emitted during for complete curing reaction,

Be curing degree, Be curing reaction speed, T is the kelvin degree of resin, and R is the gas universal constant,

Be the maximum curing degree of resin in the solidification process, think that its value is 1, l, m, n, A ₁, A ₂, E ₁, E ₂Definite through testing, as to follow material to be correlated with constant.

Material parameter used in this experiment is following:

M value 1.411, n value 1.4463, l value 2.64, A ₁(s ^-1) value 6.6349 * 10 ⁶, A ₂(s ^-1) value 3.881 * 10 ⁶, E ₁(J/mol) value 88437, E ₂(J/mol) value 76731, H _r(J/Kg) value 436000.

Exothermic function contains the unknown

so the use of an iterative method to calculate

then

calculate

method is as follows:

${\&PartialD;}^{t+\mathrm{\&Delta;t}}={\&PartialD;}^t+{\left(\frac{d\&PartialD;}{\mathrm{dt}}\right)}^{t+\mathrm{\&Delta;t}}\mathrm{\&Delta;t}$

is t curing degree constantly,

be t+ Δ t curing degree constantly.

Through programming, realize the establishment of heat release function program, in boundary condition is provided with, product is arranged to the energy source item, import the heat release function.Solution strategies is set, and discrete way is selected the second order form.Carry out temperature field simulation, obtain each moment temperature field cloud atlas of product.

Observe product 1 temperature field cloud atlas, if see that temperature minimum has only one, the number of that heater is exactly one, heater 2 is placed in the back side at frock 3 lower temperature places; Shown in the a-quadrant among Fig. 2, read the temperature peak in each temperature constantly through cloud atlas then, it is fitted to the function of " temperature-time " according to time slice; Equally also the temperature of temperature minimum point is fitted to the function of " temperature-time " according to time slice, time slice comes according to process curve, in the present embodiment; Process curve is at 0～60min, and 120～150min is the speed intensification with 1.5 ℃/min in the time, 60～120min; 150～220min is insulation in the time, so divide four time periods, is respectively 0～60min; 60～120min, 120～150min, 150～220min.Because the temperature difference in the temperature retention time section is very low, so at 60～120min, 150～220min time internal heater rate of heat release is arranged to zero, A ₂(t)=A ₄(t)=0.That calculate is 0～60min; 120～150min time internal heater rate of heat release is through simulation 0～60min, in the time period; The peak temperature can be expressed as: (temperature unit is K to T1=300+0.018t; Chronomere is second, down together), the temperature of temperature minimum point can be expressed as: the T2=300+0.01t temperature gap is: T _Cha(t) ₁=0.008t carries it into formula (11), heater thickness h in this example _i=1.5mm unites material parameter again, can solve the rate of heat release A in this short time ₁(t).In like manner, also can obtain rate of heat release A in 120～150min time period ₃(t), each rate of heat addition function is incorporated into the three-dimensional equation of heat conduction simulates, under the situation of having heaters compensation heating, realize the product simulation of Temperature; Necessary experiment is carried out, in the experimentation simultaneously in product temperature field after being optimized; According to analog case; Heater is attached to the back of frock correspondence position, and the power supply lead wire of heater can be followed the lead-in wire of thermocouple and drawn together, and is last; Analog result and experimental result are compared, realize the temperature-compensating of composite product autoclave molding product.

Above embodiment is merely explanation technological thought of the present invention, can not limit protection scope of the present invention with this, every technological thought that proposes according to the present invention, and any change of on the technical scheme basis, being done all falls within the protection domain of the present invention.

Claims (8)

1. a composite product autoclave molding product temperature compensation is characterized in that: utilize heater that the lower position of product temperature is heated, realize temperature-compensating.

2. composite product autoclave molding product temperature compensation as claimed in claim 1 is characterized in that comprising the steps:

(1) the autoclave model is simplified, divided grid, through product temperature field in the temperature field simulation software simulation composite product autoclave molding process;

(2) confirm the position of temperature maximum of points and the position of each temperature minimum point according to the temperature field of simulation;

(3) definite number and position that needs the heater of installation;

(4) confirm the temperature maximum of points each constantly with the temperature gap of each temperature minimum point;

(5) confirm the rate of heat release function of each heater;

(6) the rate of heat release function of each heater is introduced the three-dimensional equation of heat conduction, carry out analog computation, the temperature field after being optimized;

(7) if the temperature field of optimizing does not still meet the demands, repeating step (1)～step (5) meets the demands until the product temperature field.

3. composite product autoclave molding product temperature compensation as claimed in claim 1 is characterized in that: in the said step (1), the step that adopts HyperMesh to carry out the grid division is:

(11) from CATIA, derive the geometrical model of frock, product and autoclave, import among the HyperMesh then;

(12) carry out the geometry cleaning, integrate broken, remove little rounded corner, suppress unwanted line etc.;

(13) divide grid, earlier with the frock subregion, with the shape with the frock contact-making surface that supports the frock lower surface is carried out subregion, behind the subregion, the frock lower surface is divided into a plurality of grids, and the zone between each grid is exactly the cross sectional shape that supports; Frock face behind the subregion is divided two-dimensional grid; Two-dimensional grid with each grid is drawn into the entity grid then; The height of the height that stretches for supporting, the entity grid is divided in the space between the entity grid that will be drawn into by the grid two-dimensional grid, just obtains the entity grid that supports;

(14) upwards the squint distance of a frock thickness of frock lower surface two-dimensional grid is obtained the frock three-dimensional grid, more upwards the squint distance of a product thickness of frock upper surface grid is just obtained the three-dimensional grid of product;

(15) last, each face that the grid of having divided is stretched to autoclave has just been accomplished the division of grid in the autoclave zone.

4. composite product autoclave molding product temperature compensation as claimed in claim 1 is characterized in that: in the said step (2), confirm that the method for temperature maximum of points and temperature minimum point is: confirm the moment that the temperature difference is maximum according to the product thermoisopleth cloud atlas of simulation; Confirm the thermoisopleth position of this moment temperature maximum of points and the thermoisopleth position of temperature minimum point, and i=1 is numbered, 2 in the position of each minimum point; 3;, N, N are the numbers of temperature minimum point.

5. composite product autoclave molding product temperature compensation as claimed in claim 1; It is characterized in that: in the said step (3); The number of heater is identical with the number of temperature minimum point; And heater is installed in the back of the pairing frock in temperature minimum point position described in the step (2), fit with the frock back surfaces.

6. composite product autoclave molding product temperature compensation as claimed in claim 1; It is characterized in that: the content of said step (4) is: the function that all positions of confirming in the abovementioned steps (2) is become " temperature-time " at the temperature value piecewise fitting of each moment point; And the maximum temperature function deducted each minimum temperature funtion, obtain the difference T of each minimum temperature and maximum temperature _Cha(t) _i, i=1,2,3 ..., N, wherein N is the number of temperature minimum point, i is the numbering of temperature minimum point.

7. composite product autoclave molding product temperature compensation as claimed in claim 1 is characterized in that: confirm rate of heat release function A in the said step (5) _i(t) expression formula is:

$C_{p1}{\mathrm{\&rho;}}_1(T_{\mathrm{cha}}{\left(t\right)}_i{b}_1+\frac{A_i\left(t\right)h_i{b}_2}{{\mathrm{\&lambda;}}_2}{b}_2+\frac{A_i\left(t\right)h_i{b}_1}{{\mathrm{\&lambda;}}_1}\frac{b_1}{2})+C_{p2}{\mathrm{\&rho;}}_2(T_{\mathrm{cha}}{\left(t\right)}_i{b}_2+\frac{A_i\left(t\right)h_i{b}_2}{{\mathrm{\&lambda;}}_2}\frac{b_2}{2});$

$=h_i{\&Integral;}_{t_0}^t{A}_i\left(t\right)\mathrm{dt}$

Wherein, C _P1, C _P2Be respectively the specific heat of frock and product, ρ ₁, ρ ₂Be respectively the density of frock and product, T _Cha(t) _iBe frock upper surface temperature minimum point position t poor with maximum temperature constantly when not adding heater, b ₁, b ₂Be respectively the thickness of tool mold and product, h _iBe the thickness of i heater, λ ₁, λ ₂It is respectively the thermal conductivity factor of frock and product material.

8. composite product autoclave molding product temperature compensation as claimed in claim 1; It is characterized in that: the content of said step (6) is: autoclave, frock, product are carried out grid divide; Heater area is arranged to subdomain thermal source item, according to the rate of heat release function that solves in the step (5), through being programmed in the rate of heat release that heater area is set in the temperature field simulation software; The rate of heat release function is introduced the three-dimensional equation of heat conduction, the product temperature field after simulation is optimized.

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