Complex welding seam deformation prediction method based on numerical simulation

Abstract

The invention discloses a complex weld deformation prediction method based on numerical simulation, which belongs to the technical field of welding numerical simulation, and comprises the following steps: firstly, importing a finite element geometric model, then setting material attribute parameters, dividing grids, establishing surface units, establishing contact pairs, setting load and boundary conditions, and applying a predefined temperature field; and finally carrying out analog calculation and post-processing analysis. The actual welding phase change process is replaced with a contact pair mode, the time cost is greatly reduced, the welding plate is restrained by the friction force between the gravity of the welding plate and the ground according to the boundary condition, and therefore the accuracy of welding deformation of a complex welding seam is guaranteed; the problems that numerical simulation complex weld joint welding prediction is inaccurate and consumed time is long are solved.

Description

Technical Field

[0001] The invention relates to the technical field of engineering vehicle welding deformation prediction, and in particular to a complex weld deformation prediction method. Background Art

[0002] During the welding process, welding deformation will affect the dimensional accuracy of the structure and may reduce the structural bearing capacity. In addition, the welding deformation prediction is inaccurate, which often requires a lot of time to repair. Sometimes the workload of repair and correction may be more than the workload of welding. In welding simulation, sometimes the number of welds is large and the length of the weld is too long, which requires a long time for numerical simulation. Low efficiency and inaccurate prediction are problems existing in complex weld welding. Summary of the invention

[0003] In order to solve the problem of inaccurate and time-consuming prediction of complex welds in numerical simulation, the present invention analyzes the complex welds of welded plates and predicts their deformation. The method of welding deformation prediction is mastered, and the contact pair method is used to replace the actual welding phase change process. The consumption of manpower and material resources, as well as the time cost, are greatly reduced.

[0004] To achieve the above object, the present invention adopts the following scheme:

[0005] 1. A method for predicting welding deformation of complex welds based on numerical simulation, characterized in that the specific steps are as follows;

[0006] Step S1: Establishing a geometric model; Setting the unit type for model analysis;

[0007] Step S2: Set material property parameters: Mesh division:

[0008] Step S3: The weld uses a contact pair to replace the actual phase change process, and when a certain temperature is reached, the contact state changes from a separated state to a bound state;

[0009] Step S4: setting heat source and boundary conditions;

[0010] Step S5: Set the welding time analysis step and field output and history output.

[0011] Optionally, the friction coefficient of the contact surface between the welding plate and the ground, the friction coefficient of the contact surface between the pad and the welding plate, and the pad and the platform are set to be bound.

[0012] Optionally, a bonding temperature is set between the two welding plates.

[0013] Optionally, the welding numerical simulation includes a model including a geometric model, a heat source model

[0014] Optionally, the welding process parameters include: welding speed, welding power, welding energy utilization rate

[0015] Optionally, the optimal welding sequence is from the middle of the weld to both sides.

[0016] Optionally, the welding preheating temperature is the same as the ambient temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0018] Figure 1 It is a flow chart of a method for predicting welding deformation of complex welds based on numerical simulation of the present invention;

[0019] Figure 2 A schematic diagram of a three-dimensional model of a welded plate with a complex weld in an embodiment of the present invention;

[0020] Figure 3 It is a partial enlarged right view of the schematic diagram of the three-dimensional model of the welded plate with a complex weld in an embodiment of the present invention;

[0021] Figure 4 A deformation field cloud diagram of ansys apdl after welding simulation is completed, provided in an embodiment of the present invention;

[0022] Icon: 1, 2-welding plate; 3-ground; 4-backing plate; 5-welding seam Specific implementation methods

[0024] An embodiment of the present application provides a numerical simulation method for predicting welding deformation of complex welds, which can be applied to predict the deformation generated during the welding process of machines with large sizes and complex welds.

[0025] like Figure 1 As shown, the complex weld deformation prediction method provided by the present application includes:

[0026] Step S1: Establishing a geometric model; Setting the unit type for model analysis;

[0027] Step S2: Set material property parameters: Mesh division:

[0028] Step S3: The weld uses a contact pair to replace the actual phase change process, and when a certain temperature is reached, the contact state changes from a separated state to a bound state;

[0029] Step S4: setting heat source and boundary conditions;

[0030] Step S5: Set the welding time analysis step and field output and history output.

[0031] Specifically, Figure 2Schematic diagram of a three-dimensional model of a complex welded plate in an embodiment of the present invention, combined with Figure 1 In step S1, the geometric model is established by silodworks, such as Figure 2 As shown, one of the top two plates is a welding plate 2, and the other is a welding plate 1. Below the welding plate 1 is a pad 4. The pad makes the surfaces of the two welding plates of different thicknesses be in a horizontal plane. The bottom is the ground 3, and the middle of the welding plates is a weld 5. The weld shapes include two curved welds, a straight weld, and a diagonal weld.

[0032] Furthermore, a method for predicting welding deformation of complex welds based on numerical simulation is provided. In step S2, material properties are set for the welding plate, the ground and the pad. The material properties include thermal conductivity, density, specific heat capacity, expansion coefficient, Poisson's ratio, elastic modulus and yield stress that vary with temperature. In the Mesh module in ANSYS APDL, a planar 2D mesh is established for all parts; the mesh around the weld is refined, and a 3D mesh is established by sweeping; and a surface effect unit is established on the surface of the welding plate.

[0033] Further, a method for predicting welding deformation of complex welds based on numerical simulation is provided. In step S3, the Interaction module of the ANSYS APDL software is entered. First, the interaction between the contact surfaces of the welded plates is set. The contact type is face-to-face contact. The binding temperature is set. The two plates are in a separated state when welded. When the temperature of the contact pair reaches a certain temperature, the two plates become bound. The contact surface between the welding plate and the platform is set to friction. The contact surface between the pad and the welding plate is set to friction, and the pad and the platform are set to binding.

[0034] The binding state is when the temperature of the area where the heat source passes reaches a certain temperature, the two plates are welded together, and the contact state at this time changes from a separated state to a bound state. The two plates in the weld area that has not passed through are still in a separated state.

[0035] Furthermore, a method for predicting welding deformation of complex welds based on numerical simulation is provided. In step S4, the heat source adopts a Gaussian surface heat source, and the expression of the heat flux density q at a point in the heat source action area is:

[0036]

[0037] In the formula, r a is the radius of the heat source action area, r is the distance from any point in the heat source action area to the center of the heat source, r 2 =x 2 +y 2 ; Q is the welding heat input, Q=ηUI, η is the welding thermal efficiency, U is the welding voltage, and I is the welding current.

[0038] Then, the outer surface of the three-dimensional model of the welding plate with complex welds is extracted as the heat exchange surface; and the ambient temperature is created, and heat transfer is set between the welding plate and the ground and the pad.

[0039] Then, the boundary condition uses the gravity of the welded plate and the friction between the ground to constrain the welded plate.

[0040] Further, a method for predicting welding deformation of complex welds based on numerical simulation, step S5, creating a time step, solving, solving, completing, obtaining a solution result, the specific solution result includes, Figure 4 This is a cloud diagram of the simulated deformation field of ANSYS APDL after welding provided in this implementation.

[0041] The above method for simulating the deformation of a complex weld plate solves the problem of inaccurate and time-consuming prediction of complex welds in numerical simulation. The present invention analyzes the weld of the welded plate and predicts its deformation. Mastering the law of welding deformation greatly reduces the consumption of manpower and material resources, as well as time costs.

[0042] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for predicting welding deformation of complex welds based on numerical simulation, characterized in that: The specific steps are as follows: S1: Establish a geometric model and set the unit type for model analysis; S2: Set material property parameters and mesh division; S3: The weld uses contact pairs to replace the actual phase change process. When a certain temperature is reached, the contact state changes from a separated state to a bound state. S4: Set heat source and boundary conditions; S5: Set welding time analysis step and field solution, post-processing.

2. The method for predicting welding deformation of complex welds based on numerical simulation according to claim 1, characterized in that: In step S1, a finite element model is built using SilodWorks and the model is imported into ANSYS APDL.

3. The method for predicting welding deformation of complex welds based on numerical simulation according to claim 1, characterized in that: In step S2, material property parameters are set, and the material properties include thermal conductivity that varies with temperature, density, specific heat capacity, expansion coefficient, Poisson's ratio, elastic modulus, and yield stress.

4. The method for predicting welding deformation of complex welds based on numerical simulation according to claim 1, characterized in that: In step S3, the welding seam is simulated using contact pairs, which replaces the actual welding phase change process. Specifically, it includes: Enter the Interaction module of ANSYS APDL software, first set the interaction between the contact surfaces of the welded plates, set the contact type to face-to-face contact, set the binding temperature, and the initial state between the two plates is the separation state. When the temperature reaches a certain temperature, the two plates are transformed from the separation state to the binding state.

5. The method for predicting welding deformation of complex welds based on numerical simulation according to claim 1, characterized in that: In step S4, in the boundary conditions, the contact surface between the welding plate and the ground is set to friction, the contact surface between the pad and the welding plate is set to friction, and the pad and the platform are set to binding.

6. The method for predicting welding deformation of complex welds based on numerical simulation according to claim 1, characterized in that: In step S4, the expression of the heat flux density q at a point in the heat source action area is: In the formula, r a is the radius of the heat source action area, r is the distance from any point in the heat source action area to the center of the heat source, r 2 =x 2 +y 2 ; Q is the welding heat input, Q=ηUI, η is the welding thermal efficiency, U is the welding voltage, and I is the welding current.

7. The method for predicting welding deformation of complex welds based on numerical simulation according to claim 1 is characterized in that ,Step S5, create time steps, solve, the solution is completed, and the solution result is obtained.

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