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CN-122021097-A - Finite element simulation method for initial layered damage fatigue expansion of composite T-shaped stiffened plate structure

CN122021097ACN 122021097 ACN122021097 ACN 122021097ACN-122021097-A

Abstract

The invention discloses a composite T-shaped stiffened plate structure initial layering damage fatigue expansion finite element simulation method which comprises the steps of establishing a composite T-shaped stiffened plate structure finite element model containing initial layering by adopting ABAQUS, secondarily developing the ABAQUS, writing UMIXMODEFATIGUE subprograms based on a virtual crack closure technology (Virtual Crack Closure Technique, VCCT), selecting BK criteria as mixed mode criteria, selecting Paris criteria as damage fatigue expansion criteria, calling the subprograms, calculating the composite T-shaped stiffened plate structure finite element model, and realizing composite T-shaped stiffened plate structure initial layering damage fatigue expansion simulation analysis. The invention can simulate the evolution path, the expansion rate and the damage morphology of the initial layered damage of the rib-skin interface of the composite T-shaped stiffened plate structure under the fatigue load, and has great engineering value.

Inventors

  • Wang Xuanqingjiang
  • YUAN SHENFANG

Assignees

  • 南京航空航天大学

Dates

Publication Date
20260512
Application Date
20251204

Claims (8)

  1. 1. The method for simulating the initial layered damage fatigue expansion finite element of the composite T-shaped stiffened plate structure is characterized by comprising the following steps: 1) Adopting ABAQUS to establish a finite element model of the composite material T-shaped stiffened plate structure containing initial layering; 2) Performing secondary development on ABAQUS, writing UMIXMODEFATIGUE subroutines based on a virtual crack closure technique VCCT, selecting a BK criterion as a mixed mode criterion, and selecting a Paris criterion as a damage fatigue extension criterion; 3) And calling a subprogram to calculate a finite element model of the composite T-shaped reinforcing plate structure, so as to realize the initial layered damage fatigue expansion simulation analysis of the composite T-shaped reinforcing plate structure.
  2. 2. The method for simulating the initial layered damage fatigue expansion finite element of the composite T-shaped stiffened plate structure according to claim 1, wherein the step of adopting ABAQUS to build the composite T-shaped stiffened plate structure finite element model in the step 1) is as follows: 11 A geometric model of the composite T-shaped reinforced plate structure is established, and the composite T-shaped reinforced plate structure is formed by assembling two parts of ribs and a skin; 12 Determining material parameters of the composite rib and the skin, and establishing a composite layer of the composite rib and the skin; 13 Grid division is carried out on the geometric model of the composite material T-shaped stiffened plate structure; 14 Setting interaction properties and contact properties between the ribs and the skin; 15 Setting a static general analysis step and a direct cycle analysis step according to the sequence; 16 Cutting clamping areas from two ends of the finite element model of the composite T-shaped reinforcement plate structure, setting boundary conditions to fixedly support the lower clamping area, and carrying out displacement loading on the upper clamping area; 17 The method comprises the steps of) modifying keywords, wherein the keywords comprise Fracture Criterion, type=fatigue, mixed mode behavior =user, properties=6 and position= nonlocal, and then inputting USER-defined data comprising Paris criterion parameters, critical energy release rate and BK criterion parameters.
  3. 3. The method for simulating the initial layered damage fatigue expansion finite element of the composite T-shaped stiffened plate structure according to claim 2, wherein the ribs and the skins in the composite T-shaped stiffened plate structure in the step 12) are all paved by carbon fiber unidirectional tapes according to a preset paving sequence, and a composite layer is built according to the unidirectional tape material and the paving sequence of the actual structure.
  4. 4. The method for simulating the initial layered damage fatigue expansion finite element of the composite material T-shaped stiffened plate structure according to claim 2, wherein the SC8R unit is selected in the step 13), and the grid type is hexahedral sweeping grid.
  5. 5. The method for simulating the initial layered damage fatigue expansion finite element of the composite T-shaped stiffened plate structure according to claim 2, wherein in the step 14), the surface-to-surface contact is set between the rib and the skin, the slip formula is small slip, the discretization method is the node surface, the initial bonding node set is set to all nodes between the rib and the skin except for the initial layered area, the normal behavior of the contact attribute is hard contact, and the fracture criterion selects VCCT.
  6. 6. The method for simulating the initial layered damage fatigue expansion finite element of the composite T-shaped stiffened plate structure according to claim 2, wherein the static general analysis step in the step 16) applies a static load to a fatigue load average level, and the direct cyclic analysis step applies a sinusoidal fatigue load.
  7. 7. The method for simulating the initial layered damage fatigue propagation finite element of the composite T-shaped stiffened plate structure according to claim 1, wherein the specific steps of writing UMIXMODEFATIGUE the subroutine based on the virtual crack closure technique VCCT in the step 2) are as follows: 21 Opening Visual Studio compiler, inputting ABAQUS solver UMIXMODEFATIGUE subroutine interface code; 22 Defining variables to be used in the program, and reading attribute parameters customized by a user in ABAQUS; 23 Inputting BK criterion codes, and calculating the critical value of the energy release rate for driving layered expansion in the mixed damage mode And judging the total energy release rate Whether or not to be higher than Inputting Paris criterion code if Below is lower than No extension behavior occurs if Higher than The layering-damage-extend-degree is calculated according to the Paris criterion.
  8. 8. The method for simulating the initial layered damage fatigue expansion finite element of the composite T-shaped stiffened plate structure according to claim 7, wherein the step 23) is specifically as follows: total energy release rate The calculation formula is as follows: ; In the formula, 、 、 The difference between the maximum and minimum values of I, II and III energy release rates in each load cycle is called the energy release rate amplitude, and the critical value of the energy release rate for driving layered expansion in the mixed damage mode in BK criterion The calculation formula is as follows: ; wherein, eta is BK criterion custom parameter; 、 、 the critical energy release rate of the I, II and III type injury modes is calculated according to the Paris criterion, and the calculation formula is as follows: ; In the formula, For each cyclic lesion expansion rate, C and m are Paris criteria custom parameters.

Description

Finite element simulation method for initial layered damage fatigue expansion of composite T-shaped stiffened plate structure Technical Field The invention belongs to the technical field of composite materials, and particularly relates to a finite element simulation method for initial layered damage fatigue expansion of a composite material T-shaped stiffened plate structure. Background Composite materials have become one of the key materials of modern aerospace vehicles by virtue of their excellent specific strength, specific stiffness and designability. The application of the method can obviously reduce the structural weight, thereby effectively improving the fuel economy, the load capacity and the overall performance of the aircraft. With the continuous improvement of the performance requirements of the aircraft, the application range of the composite material is expanding comprehensively from a secondary bearing structure to a main bearing structure such as a wing, a fuselage and the like, and the design, analysis and verification of the structure are more demanding. In the composite main load-bearing structure, the stiffening plate is a typical structure for improving the stability and the load-bearing efficiency of the thin-wall structure. The T-shaped stiffening plate is simple in structure, clear in force transmission path, easy to manufacture and assemble, and widely applied in practice. The structure provides stable support for the skin through the ribs, allows the skin to still bear continuously after buckling, and achieves efficient utilization of materials and further light weight of the structure. However, the interface between the rib and the skin of the structure is extremely easy to generate initial delamination damage due to low energy impact and the like in the manufacturing, assembling or service process. The damage has the characteristics of strong concealment and difficult visual detection, and becomes a potential safety hazard. When the composite T-stiffener structure containing the initial delamination is subjected to fatigue loads, the initial delamination expands along the interface. In engineering, predicting the evolution path, the expansion rate and the damage morphology of the initial layering under fatigue load is one of key points. The method is completely dependent on subsequent test detection, is high in cost and long in period, and cannot provide visual damage evolution data of the whole process, so that prospective and accurate data support is lacking in damage tolerance assessment and maintenance strategy formulation of the structure. Therefore, a special finite element simulation method capable of simulating and compounding the initial layered damage expansion overall process morphology of the T-shaped reinforcement plate structure with high precision is developed, and the method has great engineering value for realizing the safety design and the optionally maintenance of the structure. Disclosure of Invention The method for simulating the initial layered damage fatigue expansion finite element of the composite T-shaped stiffened plate structure can simulate the evolution path, the expansion rate and the damage morphology of the initial layered damage of the rib-skin interface under the fatigue load, and provides the engineering personnel with the damage evolution visual data which is difficult to capture in the traditional test and is in the whole process. The method has direct guiding significance for accurately evaluating damage tolerance, positioning key overhaul areas and making a targeted nondestructive testing scheme, so that the safety maintenance and the state evaluation accuracy of the structure in the service period are remarkably improved. In order to achieve the above purpose, the invention adopts the following technical scheme: the invention relates to a finite element simulation method for initial layered damage fatigue expansion of a composite T-shaped stiffened plate structure, which comprises the following steps: 1) Adopting ABAQUS to establish a finite element model of the composite material T-shaped stiffened plate structure containing initial layering; 2) Performing secondary development on ABAQUS, writing UMIXMODEFATIGUE subroutines based on a virtual crack closure technique VCCT, selecting a BK criterion as a mixed mode criterion, and selecting a Paris criterion as a damage fatigue extension criterion; 3) And calling a subprogram to calculate a finite element model of the composite T-shaped reinforcing plate structure, so as to realize the initial layered damage fatigue expansion simulation analysis of the composite T-shaped reinforcing plate structure. Furthermore, the step of establishing the finite element model of the composite T-shaped reinforcement plate structure by adopting ABAQUS in the step 1) comprises the following steps: 11 A geometric model of the composite T-shaped reinforced plate structure is established, and the composite T-shape