CN111506972B - Method for establishing prediction model of moisture absorption amount of composite material stiffened plate and prediction method thereof - Google Patents
Method for establishing prediction model of moisture absorption amount of composite material stiffened plate and prediction method thereof Download PDFInfo
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Abstract
The invention discloses a method for establishing a prediction model of moisture absorption capacity of a composite material stiffened plate and a prediction method thereof, which comprises the steps of dividing the moisture absorption process of the I-shaped stiffened plate under a certain damp and hot environment into a 1 st moisture absorption stage and a 2 nd moisture absorption stage according to the structure of the I-shaped stiffened plate; then, based on a traditional Fick moisture absorption model, the moisture absorption amount of the side edges of the I-shaped rib composite material stiffened plate in the two moisture absorption stages is considered, and the moisture absorption amount of the stiffened plate in the 1 st moisture absorption stage and the 2 nd moisture absorption stage is obtained; and combining the moisture absorption amount of the I-shaped rib plate composite material at the boundary point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage and the moisture absorption amount of the I-shaped rib plate composite material at the 1 st moisture absorption stage and the 2 nd moisture absorption stage to obtain a prediction model of the I-shaped rib plate composite material in the damp and hot environment, and predicting the moisture absorption amount by using the prediction model. The prediction result is more accurate, and the prediction precision is higher.
Description
Technical Field
The invention belongs to the technical field of prediction of the behavior of a carbon fiber resin matrix composite material commonly used in an airplane in a damp and hot environment, and relates to a method for establishing a prediction model of the moisture absorption capacity of an I-shaped rib composite material stiffened plate in the damp and hot environment and a prediction method thereof.
Background
The composite material is a novel material appearing in the 60's of the 20 th century, has the advantages of high specific strength, high specific stiffness, good corrosion resistance and fatigue resistance and the like, and is widely applied to modern military and civil aircrafts. With the continuous improvement of design, production and manufacturing technologies, the application proportion of the composite material in military and civil aircrafts is higher and higher, and the composite material shows the trend of replacing the traditional metal material.
For large military and civil aircraft, the composite material reinforced plate structure is a complex structure commonly used for the horizontal tail, the vertical tail and other parts of the aircraft. The composite material stiffened plate is generally provided with reinforcing ribs on a composite material flat plate, the reinforcing ribs can be of various types including I-shaped, T-shaped and the like, and the type structure can be replaced by higher bearing capacity at the expense of lighter structure weight.
However, in addition to the above advantages, the composite material has a significant disadvantage of being sensitive to a damp and hot environment, which limits further application and development of the composite material. In general, the mechanical properties of the composite material are remarkably reduced under the action of a damp and hot environment for a long time. As the service time of the military and civil aircraft is long and can reach more than 20 years, the mechanical property degradation of the aircraft composite material structure caused by the damp and hot environment in a long-term service environment can threaten the flight use safety of the aircraft.
In the study of the effect of the damp-heat environment on the composite material, the moisture absorption is one of the important measures. Within a certain temperature and humidity range, the moisture absorption amount is even the most important index for measuring the composite material on the premise of not degrading the composite material. Therefore, a method for predicting the moisture absorption of the composite material in a damp and hot environment is urgently needed to lay the premise and the foundation for assessing the reduction of mechanical properties. Particularly, for a composite material structure with a complex geometric configuration, such as a composite material stiffened plate, a moisture absorption prediction method mainly aiming at a common simple laminated plate in the existing research needs to be distinguished so as to achieve the purpose of accurately predicting the moisture absorption of the structure under the damp and hot environment.
The composite material stiffened plate is a complex geometric structure comprising two typical geometric characteristics, namely a rib and a skin, the existing moisture absorption model (including a Fick moisture absorption model) is established aiming at a plate structure with a regular geometric structure, is only suitable for the plate structure with the regular geometric structure and is difficult to apply to the structure with the complex geometric structure, and the moisture absorption quantity prediction of the plate with the regular geometric structure has certain error, so that the traditional Fick moisture absorption model cannot be accurately adapted to the moisture absorption characteristics of the composite material stiffened plate, and the accuracy of the moisture absorption quantity prediction of the composite material stiffened plate based on the traditional Fick moisture absorption model is not high.
Disclosure of Invention
The embodiment of the invention aims to provide a method for establishing a prediction model of the moisture absorption capacity of a composite material stiffened plate and a problem that a traditional moisture absorption model can only be used for a plate structure with a regular geometric configuration, so that the use of the traditional moisture absorption model is limited.
Another object of the embodiment of the present invention is to provide a method for predicting moisture absorption capacity of a composite stiffened plate, so as to solve the problem that the accuracy of a method for predicting moisture absorption capacity of a composite stiffened plate based on a traditional Fick moisture absorption model is not high.
The technical scheme adopted by the embodiment of the invention is that the method for establishing the prediction model of the moisture absorption capacity of the composite material stiffened plate is carried out according to the following steps:
s1, dividing the moisture absorption process of the I-shaped rib composite material stiffened plate under a damp and hot environment into a 1 st moisture absorption stage and a 2 nd moisture absorption stage according to the structure of the I-shaped rib composite material stiffened plate, and determining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k And moisture absorption time t k ；
S2, on the basis of a traditional Fick moisture absorption model, considering the side moisture absorption amount of the I-shaped rib plate composite material at the 1 st moisture absorption stage, and determining the moisture absorption amount of the I-shaped rib plate composite material at the 1 st moisture absorption stage; and based on the traditional Fick moisture absorption model and the moisture absorption quantity M of the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k Considering the moisture absorption amount of the side edge of the I-shaped rib plate composite material at the 2 nd moisture absorption stage, determining the moisture absorption amount of the I-shaped rib plate composite material at the 2 nd moisture absorption stage;
s3, combining the moisture absorption capacity of the H-shaped rib plate composite material in the 1 st moisture absorption stage and the 2 nd moisture absorption stage and the moisture absorption capacity of the H-shaped rib plate composite material at the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stageQuantity M k And moisture absorption time t k And obtaining a prediction model of the moisture absorption capacity of the I-shaped rib composite material stiffened plate in the damp and hot environment.
Further, the implementation process of determining the moisture absorption capacity of the h-shaped rib composite material stiffened plate in the first moisture absorption stage in the step S2 is as follows:
s21, determining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 1 st moisture absorption stage Fick-1 Comprises the following steps:
wherein D is 1 The moisture absorption and diffusion coefficient of the I-shaped rib composite material stiffened plate in the 1 st moisture absorption stage is obtained according to the following formula:
wherein, the thickness of the upper edge strip, the web plate and the lower edge strip of the I-shaped rib is equal and is h 1 ；M t1 Is a moisture absorption time t 1 Amount of moisture absorption of (2), M t2 Is a moisture absorption time t 2 The amount of moisture absorbed; m ∞ The saturated moisture absorption capacity of the I-shaped rib composite material stiffened plate under the current damp and hot environment is 0<t 1 <t 2 <t k ；
S22, determining the side moisture absorption quantity M of the I-shaped rib composite material stiffened plate in the first moisture absorption stage 1 according to the structure of the I-shaped rib composite material stiffened plate Side 1 ；
Step S23, carrying out side moisture absorption M on the I-shaped rib composite material stiffened plate in the first moisture absorption stage 1 Side 1 And adding the moisture absorption amount of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 1 st moisture absorption stage, and correcting the moisture absorption amount of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 1 st moisture absorption stage to obtain the moisture absorption amount of the I-shaped rib composite material stiffened plate when the moisture absorption time is t in the 1 st moisture absorption stage.
Furthermore, the side moisture absorption amount M of the I-shaped rib composite material stiffened plate at the 1 st moisture absorption stage Side 1 Firstly, taking a skin area of a stiffened plate made of the I-shaped rib composite material, an upper edge strip and a web area of the I-shaped rib as moisture absorption areas of the stiffened plate in the 1 st moisture absorption stage; then respectively taking the skin of the I-shaped rib composite material stiffened plate, the upper edge strip of the I-shaped rib and the web plate as regular plate structures, finally respectively calculating the moisture absorption capacity of the skin of the I-shaped rib composite material stiffened plate, the upper edge strip of the I-shaped rib and the side edge of the web plate according to the sizes of the skin of the I-shaped rib composite material stiffened plate, the upper edge strip of the I-shaped rib and the side edge of the web plate, and adding the moisture absorption capacities of the skin of the I-shaped rib composite material stiffened plate, the upper edge strip of the I-shaped rib and the side edge of the web plate obtained by calculation to obtain the moisture absorption capacity M of the side edge of the I-shaped rib composite material stiffened plate at the 1 st moisture absorption stage Side 1 。
Furthermore, the side moisture absorption amount M of the upper edge strip of the I-shaped rib Side 11 Comprises the following steps:
moisture absorption M of side edge of skin Side 13 Comprises the following steps:
moisture absorption M of side edge of web Side 12 Comprises the following steps:
the side edge moisture absorption amount M of the I-shaped rib composite material stiffened plate in the first moisture absorption stage 1 Side 1 Comprises the following steps:
the moisture absorption capacity of the I-shaped rib composite material stiffened plate in the 1 st moisture absorption stage is as follows:
wherein a is the skin of the I-shaped rib composite material stiffened plate and the lengths of the upper edge strip, the web plate and the lower edge strip of the I-shaped rib, b is the skin width of the I-shaped rib composite material stiffened plate, H is the web plate width of the I-shaped rib, and H is the web plate width of the I-shaped rib 1 The thickness of the upper edge strip, the web plate and the lower edge strip of the I-shaped rib is W, the width of the upper edge strip of the I-shaped rib is W, and the width of the lower edge strip of the I-shaped rib is V; h is 3 The skin thickness of the I-shaped rib composite material stiffened plate is obtained; t is more than 0 k 。
Further, the step S2 determines the moisture absorption capacity of the i-shaped rib composite material stiffened plate at the 2 nd moisture absorption stage, and the moisture absorption capacity is determined by taking the lower edge area of the i-shaped rib as the moisture absorption area of the i-shaped rib composite material stiffened plate at the 2 nd moisture absorption stage; then, the lower edge strip of the I-shaped rib is used as a regular plate structure, and the moisture absorption quantity M of the boundary point of the I-shaped rib composite material stiffened plate at the 1 st moisture absorption stage and the 2 nd moisture absorption stage is based on the traditional Fick moisture absorption model and the I-shaped rib composite material stiffened plate k Obtaining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 2 nd moisture absorption stage Fick-2 (ii) a And calculating the side moisture absorption capacity of the lower edge strip of the I-shaped rib strip according to the side dimension of the lower edge strip of the I-shaped rib strip to obtain the side moisture absorption capacity M of the I-shaped rib strip composite material stiffened plate in the 2 nd moisture absorption stage Side 2 Finally, M is added k 、M Fick-2 、M Side 2 And adding the moisture absorption amount of the I-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage.
Furthermore, the side moisture absorption amount M of the I-shaped rib composite material stiffened plate at the 2 nd moisture absorption stage Side 2 Comprises the following steps:
wherein D is 2 The moisture absorption diffusion coefficient of the H-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage; h is a total of 2 The moisture absorption thickness h of the joint part of the lower edge strip of the I-shaped rib and the skin at the 2 nd moisture absorption stage 2 ＝h 1 ；M t3 Is a moisture absorption time t 3 Amount of moisture absorption of (2), M t4 The moisture absorption time is t 4 Amount of moisture absorption of (i) t k <t 3 <t 4 ；
The moisture absorption capacity of the I-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage is as follows:
wherein t is the moisture absorption time, t>t k 。
Further, the prediction model of the moisture absorption capacity of the i-shaped rib composite material stiffened plate in the damp and hot environment obtained in the step S3 is as follows:
wherein M is t And (4) the moisture absorption amount of the I-shaped rib composite material stiffened plate in the current damp and hot environment at the t moisture absorption time t.
Furthermore, the saturated moisture absorption M of the I-shaped rib composite material stiffened plate in the current damp and hot environment ∞ And the moisture absorption time t of the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage under the current damp and hot environment k Moisture absorption time t 1 Amount of moisture absorption M t1 Moisture absorption time t 2 Amount of moisture absorption M t2 Moisture absorption time t 3 Amount of moisture absorption M t3 And a moisture absorption time t 4 Amount of moisture absorption M t4 The moisture absorption is determined by carrying out a moisture absorption test, or is obtained by adopting the prediction of the existing moisture absorption prediction model;
determining the saturated moisture absorption amount M of the I-shaped rib composite material stiffened plate in the current damp and hot environment by carrying out a moisture absorption test ∞ And the moisture absorption time t of the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage under the current damp and hot environment k Moisture absorption time t 1 Amount of moisture absorption M t1 Moisture absorption time t 2 Amount of moisture absorption M t2 Moisture absorption time t 3 Amount of moisture absorption M t3 And a moisture absorption time t 4 Amount of moisture absorption M t4 Determining the weight or mass variable quantity of the I-shaped rib composite material stiffened plate at certain intervals in the current damp and hot environment to obtain moisture absorption data of the I-shaped rib composite material stiffened plate in the damp and hot environment; then, according to the moisture absorption data of the I-shaped rib composite material stiffened plate, determining the saturated moisture absorption M of the I-shaped rib composite material stiffened plate in the current damp and hot environment ∞ And determining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at the boundary point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage under the current damp and hot environment k Corresponding moisture absorption time t k (ii) a Finally 0 to t k Selecting the moisture absorption time t in the time period 1 And corresponding moisture absorption amount M t1 And moisture absorption time t 2 And corresponding moisture absorption amount M t2 And is greater than t k Selecting the moisture absorption time t in the time period 3 And corresponding moisture absorption amount M t3 And moisture absorption time t 4 And corresponding moisture absorption amount M t4 ；
When carrying out a moisture absorption test, calculating the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at any moisture absorption moment in the current damp-heat environment according to the following formula:
wherein m is H-shaped rib composite material stiffened plate at any time of moisture absorptionMass of etching, m 0 The quality of the dry I-shaped rib composite material stiffened plate;
h is 3 ＝h 1 Namely, the thickness of the skin of the I-shaped rib composite material stiffened plate is equal to the thickness of the upper edge strip, the lower edge strip and the web of the rib of the I-shaped rib composite material stiffened plate.
Further, the moisture absorption amount M of the I-shaped rib composite material stiffened plate in the step S1 at the boundary point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k Determining according to the ratio of the cross-sectional areas of the I-shaped rib composite material stiffened plate in the 1 st moisture absorption stage and the 2 nd moisture absorption stage, and specifically calculating according to the following formula:
the embodiment of the invention adopts another technical scheme that the method for predicting the moisture absorption capacity of the composite material stiffened plate adopts the prediction model of the moisture absorption capacity of the composite material stiffened plate to predict.
The method has the advantages that the method considers the complex geometric configuration of the I-shaped rib composite stiffened plate, firstly considers the moisture absorption of the I-shaped rib composite stiffened plate along the side edge, adds the side edge moisture absorption based on the moisture absorption predicted by the traditional Fick moisture absorption model, and corrects the moisture absorption predicted by the traditional Fick moisture absorption model; secondly, dividing the moisture absorption process of the I-shaped rib composite material stiffened plate into two moisture absorption stages, respectively considering the moisture absorption conditions of different parts of the I-shaped rib composite material stiffened plate in the two moisture absorption stages, and then taking the sum of the moisture absorption quantities of the different parts of the I-shaped rib composite material stiffened plate in the two moisture absorption stages as the predicted moisture absorption quantity of the I-shaped rib composite material stiffened plate, wherein the predicted moisture absorption quantity is more accurate and the prediction precision is higher, and meanwhile, the problem that the accuracy of the moisture absorption quantity prediction method of the composite material stiffened plate based on the traditional Fick moisture absorption model is not high is solved, and the problem that the traditional moisture absorption model is only used for a plate structure with regular geometric configuration, so that the use of the traditional moisture absorption model is limited is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 (a) is a pictorial view of a typical I-ribbed composite stiffened panel.
Fig. 1 (b) is a front view of a typical i-ribbed composite stiffened panel.
Fig. 1 (c) is a left side view of a typical i-ribbed composite stiffened panel.
Fig. 1 (d) is a top view of a typical i-ribbed composite stiffened panel.
Fig. 2 is a schematic diagram of 2-stage moisture absorption process division of a typical i-shaped rib composite stiffened plate.
Fig. 3 is a schematic diagram of the division of the 1 st moisture absorption stage and the 2 nd moisture absorption stage, wherein the parts (1), (2) and (3) are equal thickness areas.
Fig. 4 (a) is a graph showing comparison of the results of the moisture absorption amount prediction method according to the example of the present invention, the conventional prediction method, and test 1.
Fig. 4 (b) is a graph showing a comparison of the residual errors between the method for predicting the amount of moisture absorption according to the embodiment of the present invention and the conventional method (based on test result 1).
Fig. 5 (a) is a graph showing comparison between the moisture absorption amount prediction method of the present invention, the conventional prediction method, and the result of test 2.
Fig. 5 (b) is a graph showing a comparison of residual errors between the moisture absorption amount prediction method according to the embodiment of the present invention and the conventional method (based on test result 2).
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
In order to better understand the moisture absorption amount prediction method of the composite material stiffened plate in the damp and hot environment of the embodiment of the invention, the following further explains the moisture absorption amount prediction method of the composite material stiffened plate in the invention with reference to the attached drawings.
As shown in fig. 1, the composite material stiffened plate with the i-shaped rib, that is, the i-shaped rib composite material stiffened plate, includes an upper edge strip, a web plate and a lower edge strip, wherein the lower edge strip is connected to a composite material flat plate, that is, a skin, through processes such as adhesive bonding, co-curing and the like, so as to form the configuration of the i-shaped composite material stiffened plate. A practical example is given as an analysis target, and the dimension data of the i-shaped rib composite material stiffened plate shown in fig. 1 (a) to (d) are respectively a =200mm, b =150mm, w =25mm, v =55mm, h =40mm, and h = 1 ＝2.75mm，h 2 =3.05mm. The saturated moisture absorption M is achieved under a certain damp and hot environment ∞ =0.7%, corresponding to a moisture absorption time t ∞ Saturated moisture absorption amount M ∞ Can be obtained by moisture absorption experiments or by searching relevant literature data.
The embodiment of the invention provides a moisture absorption capacity prediction method of an I-shaped rib composite material stiffened plate in a damp and hot environment, and a moisture absorption capacity prediction model of the I-shaped rib composite material stiffened plate shown in the figures 1 (a) to (d) is established according to the following steps:
s1, dividing the moisture absorption process of the I-shaped rib composite material stiffened plate under a certain damp and hot environment into a 1 st moisture absorption stage and a 2 nd moisture absorption stage according to the structure of the I-shaped rib composite material stiffened plate, and determining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k And moisture absorption time t k The specific implementation process is as follows:
first according to the moisture absorption cross-sectional area of two moisture absorption stagesThe ratio determines the moisture absorption at the dividing point: determining the boundary point of the I-shaped rib composite material stiffened plate at the 1 st moisture absorption stage and the 2 nd moisture absorption stage according to the ratio of the sectional areas of the I-shaped rib composite material stiffened plate at the 1 st moisture absorption stage and the 2 nd moisture absorption stage, namely determining that the saturated moisture absorption quantity is distributed according to the sectional areas of the 1 st moisture absorption stage and the 2 nd moisture absorption stage, dividing the sectional area of the 1 st moisture absorption stage in fig. 3 by the total sectional area of the composite material stiffened plate to obtain the proportion of the sectional area of the 1 st moisture absorption stage to the total sectional area of the composite material stiffened plate, and multiplying the proportion by the final saturated moisture absorption quantity to obtain the moisture absorption quantity of the I-shaped rib composite material stiffened plate at the 1 st stage and the 2 nd stage, namely obtaining the moisture absorption quantity M of the boundary point at the 1 st moisture absorption stage and the 2 nd moisture absorption stage k To obtain the moisture absorption amount M of the boundary point between the 1 st moisture absorption stage and the 2 nd moisture absorption stage of the I-shaped rib composite material stiffened plate shown in the figures 1 (a) to (d) k Comprises the following steps:
wherein b is the skin width of the I-shaped rib composite material stiffened plate, H is the web width of the I-shaped rib, and H is 1 The thickness of the upper edge strip, the web plate and the lower edge strip of the I-shaped rib is equal, w is the width of the upper edge strip of the I-shaped rib, and v is the width of the lower edge strip of the I-shaped rib.
Then, according to the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k Determining the moisture absorption time t of the I-shaped rib composite material stiffened plate at the boundary point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k 。
The composite material stiffened plate is a structure with a complex geometric configuration and comprises two typical geometric characteristics, namely a rib and a skin, so that the thickness of a connecting part of the rib and the skin is different from that of other parts, and the moisture absorption amounts of the parts with different thicknesses are different under the same moisture absorption time, so that a boundary point is determined according to the ratio of the moisture absorption cross-sectional areas of the 1 st moisture absorption stage and the 2 nd moisture absorption stage, the moisture absorption process of the composite material stiffened plate is divided into the 1 st moisture absorption stage and the 2 nd moisture absorption stage, and the predicted moisture absorption amount is more accurate according to the actual moisture absorption process.
And S2, determining the moisture absorption capacity of the I-shaped rib composite material stiffened plate in the 1 st moisture absorption stage by considering the moisture absorption capacity of the side edge (thickness surface) of the I-shaped rib composite material stiffened plate in the 1 st moisture absorption stage based on the traditional Fick moisture absorption model. Because the traditional Fick moisture absorption model only considers the moisture absorption amount along the normal phase of the plane of the plate to be predicted, and does not consider the moisture absorption amount at the side edge of the plate to be predicted, the moisture absorption amount prediction based on the traditional Fick moisture absorption model is not accurate enough. The embodiment of the invention provides a prediction method considering the side moisture absorption capacity of an I-shaped rib composite material stiffened plate in a 1 st moisture absorption stage based on a traditional Fick moisture absorption model, and the Fick moisture absorption model is corrected by adding the side moisture absorption capacity of the I-shaped rib composite material stiffened plate in the 1 st moisture absorption stage, and the method is specifically realized in the following steps:
s21, determining the moisture absorption quantity of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 1 st moisture absorption stage as follows:
wherein D is 1 The moisture absorption and diffusion coefficient of the ribbed plate made of the I-shaped rib composite material in the 1 st moisture absorption stage can be obtained according to the following formula:
wherein M is t1 Is a moisture absorption time t 1 Amount of moisture absorption of (2), M t2 Is a moisture absorption time t 2 The amount of moisture absorbed; m t1 And M t2 The moisture absorption capacity prediction model can be obtained by carrying out a moisture absorption test, can also be obtained by adopting the prediction of the existing moisture absorption capacity prediction model, and can also be obtained by searching the existing relevant literature data. t is t 1 And t 2 At any two time points in the 1 st moisture absorption stage, namely 0<t 1 <t 2 <t k Selecting t as initial stage of the 1 st moisture absorption stage 1 Trying to select t at the end of the 1 st moisture absorption stage 2 And the calculated moisture absorption diffusion coefficient is closer to the true value.
S22, determining the side moisture absorption quantity M of the I-shaped rib composite material stiffened plate in the first moisture absorption stage 1 according to the structure of the I-shaped rib composite material stiffened plate Side 1 Comprises the following steps:
b is the skin width of the I-shaped rib composite material stiffened plate, H is the web plate width of the I-shaped rib, w is the upper edge strip width of the I-shaped rib, and v is the lower edge strip width of the I-shaped rib; h is 3 The skin thickness of the rib plate made of the I-shaped rib composite material; t is more than 0 k . Example h of the invention 3 ＝h 1 Namely, the thickness of the skin of the I-shaped rib composite material stiffened plate is equal to the thickness of the upper edge strip, the lower edge strip and the web of the rib of the I-shaped rib composite material stiffened plate.
Because the conventional Fick moisture absorption model mainly predicts the moisture absorption amount along the planar normal phase of a plate to be predicted, the conventional Fick moisture absorption model is mainly influenced by the planar two-dimensional size, namely the length and the width of a composite material stiffened plate. In the embodiment of the invention, the moisture absorption amount from the side edge of the I-shaped rib composite material reinforcing plate is determined by the ratio of the thickness dimension to the planar two-dimensional dimension, so that the moisture absorption amount is predicted by taking the parts (1), (2) and (3) of the composite material reinforcing plate shown in figure 3, namely the upper edge strip, the web plate and the lower edge strip of the I-shaped rib, as regular plate structures. A regular panel comprises 4 sides, two of which are sized by length and thickness dimensions and the other two by width and thickness dimensions, so that the amount of side moisture absorption is determined by the ratio of length to thickness and the ratio of width to thickness, taking into account. Can be obtained byDetermining the side moisture absorption M of the 1 st moisture absorption stage Side 1 : taking the example of (1) component, i.e. the upper edge strip, in fig. 3, this component can be considered as a plate with a regular geometrical configuration, and the two dimensions of its plane, i.e. its length a, width w and thickness h 1 Therefore, the side edge moisture absorption amount of the upper edge strip in the 1 st moisture absorption stage is obtained according to the size of the side surface of the upper edge strip
Similarly, the moisture absorption amount of the side edge of the part (3) in fig. 3, i.e. the lower edge strip in the 1 st moisture absorption stage is
Since the part (2) is connected with the parts (1) and (3) up and down, the moisture absorption amount of the part (2) in fig. 3, namely the side edge of the web plate in the 1 st moisture absorption stage is equal to
Then adding the skin of the I-shaped rib composite material stiffened plate, the upper edge strip of the I-shaped rib and the side moisture absorption amount of the web plate in the 1 st moisture absorption stage to obtain the side moisture absorption amount M of the I-shaped rib composite material stiffened plate in the 1 st moisture absorption stage Side 1 。
Step S23, carrying out side moisture absorption M on the I-shaped rib composite material stiffened plate in the first moisture absorption stage 1 Side 1 Adding the moisture absorption amount of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 1 st moisture absorption stage, and correcting the moisture absorption amount of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 1 st moisture absorption stage to obtain the moisture absorption amount of the I-shaped rib composite material stiffened plate when the moisture absorption time is t in the 1 st moisture absorption stage:
wherein t is more than 0 and less than t k 。
Meanwhile, based on the traditional Fick moisture absorption model and the moisture absorption capacity M of the stiffened plate made of the I-shaped rib composite material at the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k Consider the I-shapeThe moisture absorption amount of the I-shaped rib plate composite material at the side edge of the 2 nd moisture absorption stage is determined: before the beginning of the 2 nd moisture absorption stage, the total moisture absorption capacity of the I-shaped rib composite material stiffened plate reaches the moisture absorption capacity M of the dividing point k Therefore, the moisture absorption capacity of the I-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage is the moisture absorption capacity M at the dividing point k On the basis of the formula (I), the moisture absorption quantity M predicted based on the traditional Fick moisture absorption model in the 2 nd moisture absorption stage is added Fick-2 And its side moisture absorption amount M in the 2 nd moisture absorption stage Side 2 。
The moisture absorption capacity of the H-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage is that the lower edge strip area of the H-shaped rib is firstly used as the moisture absorption area of the H-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage; then, the lower edge strip of the I-shaped rib is used as a regular plate structure, and the moisture absorption quantity M of the boundary point of the I-shaped rib composite material stiffened plate at the 1 st moisture absorption stage and the 2 nd moisture absorption stage is based on the traditional Fick moisture absorption model and the I-shaped rib composite material stiffened plate k Obtaining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 2 nd moisture absorption stage Fick-2 (ii) a And calculating the side edge moisture absorption amount of the lower edge strip of the I-shaped rib strip according to the side surface size of the lower edge strip of the I-shaped rib strip to obtain the side edge moisture absorption amount M of the I-shaped rib strip composite material stiffened plate in the 2 nd moisture absorption stage Side 2 Finally, M is added k 、M Fick-2 、M Side 2 Adding to obtain the moisture absorption capacity of the I-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage:
M 2 ＝M k +M Fick-2 +M side 2 ；
Wherein h is 2 Indicating the lower edge of the I-shaped ribThe thickness of the strip-to-skin bond at the 2 nd hygroscopic stage, h in the example of the invention 2 ＝h 1 Namely, the moisture absorption thickness of the joint part of the lower edge strip of the I-shaped rib and the skin at the 2 nd moisture absorption stage is the thickness of the lower edge strip, and the width of the part at the 2 nd moisture absorption stage is b, and the length is a.
D 2 The moisture absorption, diffusion and moisture absorption of the I-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage are calculated by the following formula:
wherein M is t3 Is a moisture absorption time t 3 Amount of moisture absorption of (2), M t4 The moisture absorption time is t 4 The amount of moisture absorbed; t is t 3 And t 4 Selecting t for any two time points in the 2 nd moisture absorption stage as much as possible in the initial stage of the 2 nd moisture absorption stage 3 Trying to select t at the end of the 2 nd moisture absorption stage 4 I.e. t k <t 3 <t 4 。
The moisture absorption amount in the final 2 nd moisture absorption stage is:
wherein t is the moisture absorption time, t>t k 。
S3, combining the moisture absorption capacity of the I-shaped rib plate composite material reinforcing plate in the 1 st moisture absorption stage and the 2 nd moisture absorption stage and the moisture absorption capacity M of the rib plate at the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k And moisture absorption time t k And finally, predicting the moisture absorption capacity of the I-shaped rib composite material stiffened plate by using the obtained prediction model of the moisture absorption capacity of the I-shaped rib composite material stiffened plate in the damp-heat environment.
The obtained prediction model of the moisture absorption of the I-shaped rib composite material stiffened plate in the damp and hot environment is as follows:
the embodiment of the invention can determine the saturated moisture absorption amount M of the I-shaped rib composite material stiffened plate in the current damp and hot environment by carrying out a moisture absorption test ∞ And the moisture absorption time t of the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage under the current damp and hot environment k Moisture absorption time t 1 Amount of moisture absorption M t1 Moisture absorption time t 2 Amount of moisture absorption M t2 Moisture absorption time t 3 Amount of moisture absorption M t3 And a moisture absorption time t 4 Amount of moisture absorption M t4 。
Determining the saturated moisture absorption amount M of I-shaped rib composite material stiffened plate in the current damp and hot environment by carrying out a moisture absorption test ∞ And the moisture absorption time t of the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage under the current damp and hot environment k Moisture absorption time t 1 Amount of moisture absorption M t1 Moisture absorption time t 2 Amount of moisture absorption M t2 Moisture absorption time t 3 Amount of moisture absorption M t3 And a moisture absorption time t 4 Amount of moisture absorption M t4 Determining the weight or mass variable quantity of the I-shaped rib composite material stiffened plate at a certain interval (24 hours are recommended) in the current damp and hot environment to obtain the moisture absorption data of the I-shaped rib composite material stiffened plate in the damp and hot environment; then, according to the moisture absorption data of the I-shaped rib composite material stiffened plate, determining the saturated moisture absorption M of the I-shaped rib composite material stiffened plate in the current damp and hot environment ∞ And determining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at the boundary point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage under the current damp and hot environment k Corresponding moisture absorption time t k (ii) a Finally 0 to t k Selecting the moisture absorption time t in the time period 1 And corresponding moisture absorption amount M t1 And moisture absorption time t 2 And corresponding moisture absorption amount M t2 And is greater than t k Selecting the moisture absorption time t in the time period 3 And corresponding moisture absorption amount M t3 And moisture absorption time t 4 And corresponding moisture absorption amount M t4 。
When carrying out a moisture absorption test, calculating the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at any moisture absorption moment in the current damp-heat environment according to the following formula:
wherein m is the mass of the I-shaped rib composite material stiffened plate at any moisture absorption moment 0 The quality of the dry I-shaped rib composite material stiffened plate.
The moisture absorption amount of any moisture absorption time in the whole moisture absorption process can be predicted by adopting the existing moisture absorption amount prediction model to obtain the moisture absorption amount M of the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k The moisture absorption time t of the corresponding dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k Namely, the dividing point of the 1 st absorption stage and the 2 nd absorption stage is determined.
To examine the accuracy of the moisture absorption prediction method proposed in the present embodiment, it was examined by correlation test data and compared with the existing literature "Zhang Tiejun, li Shuli, chang fei. An experimental and numerical analysis for doped Composite panel project to shear loading in a hierarchical environment [ J ]. Composite structures,2016,138, 107-115".
Fig. 4 (a) shows the prediction effect of the moisture absorption amount prediction method according to the embodiment of the present invention and the method disclosed in the reference on test data 1, where test data 1 is the moisture absorption amount data of the composite material stiffened plate obtained by performing the moisture absorption experiment in the water bath environment at 70 ℃ in the hot and humid environment to verify the effectiveness of the method provided by the present invention. As can be seen from fig. 4 (a), the method of the embodiment of the present invention is significantly better than the method disclosed in the related document in the 1 st moisture absorption stage, and the superiority of the two models cannot be clearly distinguished visually in the 2 nd moisture absorption stage. Therefore, the residuals of the two models are plotted in fig. 4 (b), and as can be seen from fig. 4 (b), the residuals of the prediction results of the method of the embodiment of the present invention are closer to the 0 axis than the residuals of the prediction of the reference in the whole, and the predicted values of the method of the embodiment of the present invention are closer to the experimental values, no matter in the 1 st moisture absorption stage or the 2 nd moisture absorption stage. For quantitative examination, the sum of squares of the residual errors of the method of the embodiment of the invention and the method of the reference in the 1 st moisture absorption stage, the 2 nd moisture absorption stage and the whole process stage are respectively calculated, the sum of the squares of the residual errors of the method of the reference in the 1 st moisture absorption stage, the 2 nd moisture absorption stage and the whole process stage is 0.0743, 0.0580 and 0.1322 respectively, and the sum of the square of the residual errors of the method of the embodiment of the invention is 0.0376, 0.0547 and 0.0923 respectively, so that the sum of the squares of the residual errors of the method of the embodiment of the invention in the 1 st stage, the 2 nd stage and the whole process stage is smaller than the predicted corresponding value of the reference, and further proves the effectiveness and the accuracy of the method of the embodiment of the invention.
To further verify the effectiveness of the method of the embodiment of the present invention, the prediction method of the embodiment of the present invention is applied to analyze the test data in the literature "Zhang Tiejun, li Shuli, chang fei. An experimental and a numerical analysis for a constrained Composite panel summary to a paint loading in a geological environment [ J ]. Composite structures,2016, 138". The moisture absorption test piece material in the document is a carbon fiber epoxy resin matrix composite material, and the moisture absorption environment is 70 ℃ and RH85%. The moisture absorption dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage of the document is (30,0.7) (namely, the dividing point time is 30, and the moisture absorption amount is 0.7), as can be seen from fig. 5 (a), the method of the embodiment of the invention is obviously superior to the method of the document in the 1 st moisture absorption stage, and the accuracy of the method of the embodiment of the invention and the method of the document cannot be obviously distinguished in the 2 nd moisture absorption stage, therefore, the residual errors of the two models are plotted in fig. 5 (b), as can be seen from fig. 5 (b), the whole residual error of the predicted value of the method of the embodiment of the invention is closer to the 0 axis than the method of the document, the sum of squares of residuals of the method in the 1 st moisture absorption stage, the 2 nd moisture absorption stage and the whole process stage is 0.0179, 0.0378 and 0.0557 respectively, and the sum of squares of residuals of the method in the embodiment of the invention is 0.0104, 0.0257 and 0.0361 respectively, so that the sum of squares of residuals of the method in the embodiment of the invention in the 1 st moisture absorption stage, the 2 nd moisture absorption stage and the whole process stage is smaller than the corresponding value of the method in the related literature, and further illustrates the effectiveness and the accuracy of the method in the embodiment of the invention.
The embodiment of the invention considers that because the thicknesses of the composite material reinforced plates are different, in the moisture absorption process, the area with smaller thickness reaches the moisture absorption equilibrium state firstly, and then the inside of the area with larger thickness gradually reaches the moisture absorption equilibrium state, namely the moisture absorption process of the stiffened plate is divided into two stages. The improved Fick moisture absorption model is respectively obeyed in each stage, the improved Fick moisture absorption model is based on the traditional Fick moisture absorption model, the moisture absorption amount of the composite material laminated plate from the material thickness plane is considered, the predicted moisture absorption process is more consistent with the real moisture absorption process, the predicted result is closer to the real value, and the predicted result is more accurate and reliable.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. The method for establishing the prediction model of the moisture absorption capacity of the composite material stiffened plate is characterized by comprising the following steps of:
s1, dividing the moisture absorption process of the I-shaped rib composite material stiffened plate under a damp and hot environment into a 1 st moisture absorption stage and a 2 nd moisture absorption stage according to the structure of the I-shaped rib composite material stiffened plate, and determining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k And moisture absorption time t k ；
S2, based on a traditional Fick moisture absorption model, considering the moisture absorption amount of the side edge of the I-shaped rib plate composite material at the 1 st moisture absorption stage, and determining the moisture absorption amount of the I-shaped rib plate composite material at the 1 st moisture absorption stage; and based on the traditional Fick moisture absorption model and the moisture absorption quantity M of the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k Considering the moisture absorption amount of the side edge of the I-shaped rib plate composite material at the 2 nd moisture absorption stage, determining the moisture absorption amount of the I-shaped rib plate composite material at the 2 nd moisture absorption stage;
step S3, combining the I-shaped ribsThe moisture absorption capacity of the rib plate of the strip composite material in the 1 st moisture absorption stage and the 2 nd moisture absorption stage, and the moisture absorption capacity M of the I-shaped rib plate of the rib composite material at the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage k And moisture absorption time t k And obtaining a prediction model of the moisture absorption capacity of the I-shaped rib composite material stiffened plate in the damp and hot environment.
2. The method for establishing the prediction model of the moisture absorption capacity of the composite material stiffened plate according to claim 1, wherein the step S2 is implemented by determining the moisture absorption capacity of the I-shaped rib composite material stiffened plate in the first moisture absorption stage as follows:
s21, determining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 1 st moisture absorption stage Fick-1 Comprises the following steps:
wherein D is 1 The moisture absorption and diffusion coefficient of the I-shaped rib composite material stiffened plate in the 1 st moisture absorption stage is obtained according to the following formula:
wherein the thicknesses of the upper edge strip, the web plate and the lower edge strip of the I-shaped rib are equal and are all h 1 ；M t1 The moisture absorption time is t 1 Amount of moisture absorption of (2), M t2 The moisture absorption time is t 2 The amount of moisture absorbed; m ∞ The saturated moisture absorption capacity of the I-shaped rib composite material stiffened plate under the current damp and hot environment is 0<t 1 <t 2 <t k ；
S22, determining the side moisture absorption quantity M of the I-shaped rib composite material stiffened plate in the first moisture absorption stage 1 according to the structure of the I-shaped rib composite material stiffened plate Side 1 ；
Step S23, arranging a rib plate on the first side of the I-shaped rib composite material1 side moisture absorption amount M in moisture absorption stage Side 1 And adding the moisture absorption amount of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 1 st moisture absorption stage, and correcting the moisture absorption amount of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 1 st moisture absorption stage to obtain the moisture absorption amount of the I-shaped rib composite material stiffened plate when the moisture absorption time is t in the 1 st moisture absorption stage.
3. The method for establishing the prediction model of the moisture absorption capacity of the composite material stiffened plate according to claim 2, wherein the moisture absorption capacity M of the side edge of the I-shaped rib composite material stiffened plate at the first moisture absorption stage 1 is determined by the method Side 1 Firstly, taking a skin area of a stiffened plate made of the I-shaped rib composite material, an upper edge strip and a web area of the I-shaped rib as moisture absorption areas of the stiffened plate in the 1 st moisture absorption stage; then respectively taking the skin of the I-shaped rib composite material stiffened plate, the upper edge strip of the I-shaped rib and the web plate as regular plate structures, finally respectively calculating the moisture absorption capacity of the skin of the I-shaped rib composite material stiffened plate, the upper edge strip of the I-shaped rib and the side edge of the web plate according to the sizes of the skin of the I-shaped rib composite material stiffened plate, the upper edge strip of the I-shaped rib and the side edge of the web plate, and adding the moisture absorption capacities of the skin of the I-shaped rib composite material stiffened plate, the upper edge strip of the I-shaped rib and the side edge of the web plate obtained by calculation to obtain the moisture absorption capacity M of the side edge of the I-shaped rib composite material stiffened plate at the 1 st moisture absorption stage Side 1 。
4. The method for establishing the prediction model of the moisture absorption capacity of the composite material stiffened plate according to claim 3, wherein the moisture absorption capacity M of the side edge of the upper edge strip of the I-shaped rib is M Side 11 Comprises the following steps:
moisture absorption M of side edge of skin Side 13 Comprises the following steps:
moisture absorption M of the side edge of the web Side 12 Comprises the following steps:
the side edge moisture absorption amount M of the I-shaped rib composite material stiffened plate in the first moisture absorption stage 1 Side 1 Comprises the following steps:
the moisture absorption capacity of the I-shaped rib composite material stiffened plate in the first moisture absorption stage is as follows:
wherein a is the skin of the I-shaped rib composite material stiffened plate and the lengths of the upper edge strip, the web plate and the lower edge strip of the I-shaped rib, b is the skin width of the I-shaped rib composite material stiffened plate, H is the web plate width of the I-shaped rib, w is the upper edge strip width of the I-shaped rib, and v is the lower edge strip width of the I-shaped rib; h is 3 The skin thickness of the rib plate made of the I-shaped rib composite material; t is more than 0 and less than t k 。
5. The method for establishing the prediction model of the moisture absorption capacity of the rib plate made of the composite material according to claim 4, wherein the step S2 is used for determining the moisture absorption capacity of the rib plate made of the I-shaped rib composite material in the 2 nd moisture absorption stage, namely, the lower edge area of the I-shaped rib is used as the moisture absorption area of the rib plate made of the I-shaped rib composite material in the 2 nd moisture absorption stage; then, taking the lower edge strips of the I-shaped ribs as a regular plate structure, and based on the traditional Fick moisture absorption model and the I-shaped rib composite material stiffened plate at the 1 st moisture absorption stage and the 1 st moisture absorption stage2 moisture absorption amount M at boundary point in moisture absorption stage k Obtaining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate based on the traditional Fick moisture absorption model in the 2 nd moisture absorption stage Fick-2 (ii) a And calculating the side edge moisture absorption amount of the lower edge strip of the I-shaped rib strip according to the side surface size of the lower edge strip of the I-shaped rib strip to obtain the side edge moisture absorption amount M of the I-shaped rib strip composite material stiffened plate in the 2 nd moisture absorption stage Side 2 Finally, M is added k 、M Fick-2 、M Side 2 And adding the moisture absorption amount of the I-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage.
6. The method for establishing the prediction model of the moisture absorption capacity of the composite stiffened plate according to claim 5, wherein the side moisture absorption capacity M of the I-shaped rib composite stiffened plate at the 2 nd moisture absorption stage Side 2 Comprises the following steps:
wherein D is 2 The moisture absorption diffusion coefficient of the rib plate made of the I-shaped rib composite material in the 2 nd moisture absorption stage is set; h is 2 The moisture absorption thickness h of the joint of the lower edge strip of the I-shaped rib and the skin in the 2 nd moisture absorption stage 2 ＝h 1 ；M t3 Is a moisture absorption time t 3 Amount of moisture absorption of (2), M t4 Is a moisture absorption time t 4 Amount of moisture absorption of (g), t k <t 3 <t 4 ；
The moisture absorption capacity of the I-shaped rib composite material stiffened plate in the 2 nd moisture absorption stage is as follows:
wherein the content of the first and second substances,t is the moisture absorption time t>t k 。
7. The method for establishing the prediction model of the moisture absorption capacity of the rib plate made of the composite materials according to the claim 6, wherein the prediction model of the moisture absorption capacity of the rib plate made of the I-shaped rib composite materials in the damp and hot environment obtained in the step S3 is as follows:
wherein M is t The moisture absorption amount of the I-shaped rib composite material stiffened plate in the current damp and hot environment at the t moisture absorption time t.
8. The method for establishing the prediction model of the moisture absorption capacity of the rib plate made of composite materials according to claim 7, wherein the saturated moisture absorption capacity M of the rib plate made of I-shaped rib composite materials under the current damp and hot environment is M ∞ And the moisture absorption time t of the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage under the current damp and hot environment k Moisture absorption time t 1 Amount of moisture absorption M t1 Moisture absorption time t 2 Amount of moisture absorption M t2 Moisture absorption time t 3 Amount of moisture absorption M t3 And a moisture absorption time t 4 Amount of moisture absorption M t4 The moisture absorption capacity is determined by carrying out a moisture absorption test or is obtained by adopting the prediction of the existing moisture absorption capacity prediction model;
the saturated moisture absorption amount M of the I-shaped rib composite material stiffened plate in the current damp and hot environment is determined by carrying out a moisture absorption test ∞ And the moisture absorption time t of the dividing point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage under the current damp and hot environment k Moisture absorption time t 1 Amount of moisture absorption M t1 Moisture absorption time t 2 Amount of moisture absorption M t2 Moisture absorption time t 3 Amount of moisture absorption M t3 And a moisture absorption time t 4 Amount of moisture absorption M t4 Determining the weight or mass variable quantity of the I-shaped rib composite material stiffened plate at certain intervals in the current damp and hot environment to obtain the weight or mass variable quantityMoisture absorption data of I-shaped rib composite material stiffened plates in a damp and hot environment; then, according to the moisture absorption data of the I-shaped rib composite material stiffened plate, determining the saturated moisture absorption M of the I-shaped rib composite material stiffened plate in the current damp and hot environment ∞ And determining the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at the boundary point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage under the current damp and hot environment k Corresponding moisture absorption time t k (ii) a Finally 0 to t k Selecting the moisture absorption time t in the time period 1 And corresponding moisture absorption amount M t1 And moisture absorption time t 2 And corresponding moisture absorption amount M t2 And is greater than t k Selecting the moisture absorption time t in the time period 3 And corresponding moisture absorption amount M t3 And moisture absorption time t 4 And corresponding moisture absorption amount M t4 ；
When carrying out a moisture absorption test, calculating the moisture absorption quantity M of the I-shaped rib composite material stiffened plate at any moisture absorption moment in the current damp-heat environment according to the following formula:
wherein m is the mass of the I-shaped rib composite material stiffened plate at any moisture absorption moment 0 The quality of the dry I-shaped rib composite material stiffened plate;
h is mentioned 3 ＝h 1 Namely, the thickness of the skin of the I-shaped rib composite material stiffened plate is equal to the thickness of the upper edge strip, the lower edge strip and the web of the rib of the I-shaped rib composite material stiffened plate.
9. The method for establishing the prediction model of the moisture absorption capacity of the rib plate made of the composite material according to any one of claims 1 to 8, wherein the moisture absorption capacity M of the rib plate made of the I-shaped rib composite material at the boundary point of the 1 st moisture absorption stage and the 2 nd moisture absorption stage in the step S1 is determined according to the moisture absorption capacity M of the rib plate made of the I-shaped rib composite material k Determining according to the ratio of the cross-sectional areas of the I-shaped rib composite material stiffened plate in the 1 st moisture absorption stage and the 2 nd moisture absorption stage, and specifically calculating according to the following formula:
10. the method for predicting the moisture absorption capacity of the composite stiffened plate is characterized in that the prediction model of the moisture absorption capacity of the composite stiffened plate according to claim 7 or 8 is adopted for prediction.
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