Mechanical property prediction and failure evaluation method for dissimilar material connections

Abstract

The present invention discloses a method for predicting the mechanical properties and failure evaluation of heterogeneous material connections, including: (1) designing connection schemes with different upper plate thicknesses, lower plate thicknesses, rivet diameters, and adhesive thicknesses; (2) constructing a material constitutive model, and establishing a heterogeneous material connection simulation model based on Lsdyn; (3) obtaining the optimal tangential load function index value under different design schemes; (4) constructing a mapping relationship between the upper plate thickness, lower plate thickness, rivet diameter, adhesive thickness and the maximum peak force, the displacement corresponding to the maximum peak force, the fracture displacement, the optimal tangential load function index value, and the failure mode; (5) calculating and obtaining a simulated force-displacement curve, and combining the failure mode obtained by a radial basis function neural network model to achieve prediction of the mechanical properties and failure evaluation of heterogeneous material connections. The method for predicting the mechanical properties and failure evaluation of heterogeneous material connections is used for predicting the mechanical properties and failure evaluation of heterogeneous material connections, and can assist in the design of lightweight product structures.

Description

Technical Field

[0001] The invention relates to a method for predicting mechanical properties and failure evaluation of heterogeneous material connections, belonging to the technical field of heterogeneous material connection evaluation. Background Art

[0002] Heterogeneous material joining technology has been widely promoted and applied in many fields, including aerospace, automobile, electronics, machinery, energy, etc. In the automotive field, heterogeneous material joining technology can be used to manufacture lighter and stronger automobile structures, thereby improving the safety and economy of automobiles.

[0003] Compared with the traditional lightweight body structure, the current trend of multi-material body means that spot welding is no longer the only way to connect the structure. Instead, spot welding, gluing, riveting or mixed connection methods are selected according to the properties of the connected materials. However, for riveting and glue-riveting composite connections, the failure mechanism of these connection methods and the interaction mechanism with the connected structure and materials are very complex. There is a lack of systematic simulation prediction models, which makes it impossible to guarantee the quality and efficiency of lightweight body design under complex working conditions. In addition, the modeling methods and failure fracture prediction methods of each connection method are different.

[0004] like Figure 2 The dissimilar material connection model shown includes an upper plate 2 and a lower plate 1. There is an adhesive layer 3 area between a part of the upper plate 2 and a part of the lower plate 1. The upper plate 2 and the lower plate 1 are connected at the adhesive layer 3 area by a rivet 4. The upper plate 2 is made of steel and the lower plate 1 is made of aluminum. The upper plate 2 and the lower plate 1 are made of different materials. Mechanical property prediction and failure evaluation must be performed when designing such a dissimilar material connection.

[0005] The patent application publication number CN 116108719 A discloses a finite element calculation method and strength verification method for the mechanical state of bolted connection, including: establishing a finite element model corresponding to the bolted connection structure according to the real geometric structure of each component in the bolted connection structure; performing two finite element analysis steps, the first step includes applying a fixed constraint to the bolt head in the finite element model and applying an angle constraint to the nut in the finite element model; the second step includes removing the fixed constraint applied to the bolt head in the finite element model, applying a fixed constraint to one of the clamped parts between the upper clamped part and the lower clamped part in the finite element model, and applying an external load to the other clamped part; according to the data obtained in the two finite element analysis steps, solving the flexibility of the clamped part, the load coefficient and the second minimum preload value. The technical solution shown in this application can accurately verify the strength of the bolted connection and determine the appropriate bolt specifications, material types and tightening torque. However, this method is not suitable for the prediction of mechanical properties and failure evaluation of heterogeneous material connections. Summary of the invention

[0006] The main technical problem solved by the present invention is to provide a method for predicting the mechanical properties and failure evaluation of heterogeneous material connections. The method is used for predicting the mechanical properties and failure evaluation of heterogeneous material connections and can assist in the design of lightweight product structures.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: to provide a method for predicting the mechanical properties and failure evaluation of dissimilar material connections, comprising the following steps:

[0008] (1) Design connection schemes with different upper plate thickness, lower plate thickness, rivet diameter, and adhesive thickness through DOE experiment (experimental design). Obtain force-displacement curves through experimental tests, and extract the maximum peak force, displacement corresponding to the maximum peak force, fracture displacement, and failure mode. The failure mode includes upper plate fracture, lower plate fracture, and rivet fracture.

[0009] (2) Construct a material constitutive model and establish a simulation model for the connection of dissimilar materials based on Lsdyn;

[0010] (3) Designing different tangential load function index values ​​through DOE experimental design schemes, taking the maximum peak force, the displacement corresponding to the maximum peak force, and the fracture displacement obtained in step (1) as input values ​​of the constitutive model, and starting a large number of simulations using the simulation model established in step (2), and obtaining the optimal tangential load function index values ​​under different DOE design schemes by comparing the force-displacement curves of the experimental test with the force-displacement curves obtained by simulation;

[0011] (4) A radial basis function neural network model is used to construct the mapping relationship between the upper plate thickness, lower plate thickness, rivet diameter, bonding thickness and maximum peak force, displacement corresponding to the maximum peak force, fracture displacement, optimal tangential load function index value, and failure mode;

[0012] (5) Based on the radial basis function neural network model, the maximum peak force, the displacement corresponding to the maximum peak force, the fracture displacement, the optimal tangential load function index value, and the failure mode under the connection scheme of fixed upper plate thickness, lower plate thickness, rivet diameter, and bonding thickness are calculated. Based on the connection simulation model of step (2), the maximum peak force, the displacement corresponding to the maximum peak force, the fracture displacement, and the optimal tangential load function index value obtained above are used as the material constitutive model parameter input, and the simulated force-displacement curve is calculated. Combined with the failure mode obtained by the radial basis function neural network model, the mechanical property prediction and failure evaluation of the connection of dissimilar materials can be realized.

[0013] Preferably, the material constitutive model relation in step (2) is:

[0014]

[0015]

[0016] f t :Real-time test force

[0017] f t Max : Maximum peak force

[0018] δ t :Real-time test displacement

[0019] δ t Max : Displacement corresponding to the maximum peak force

[0020] η Max : Damage measure, consistent with strain, i.e. δ t / δ t Max

[0021] ξ t : Inverse value, constant, displacement corresponding to maximum peak force / fracture displacement

[0022] x is the exponential value of the tangential load function.

[0023] The beneficial effects of the present invention are as follows: the method for predicting the mechanical properties and failure evaluation of dissimilar material connections of the present invention is used for predicting the mechanical properties and failure evaluation of dissimilar material connections, which can assist in the design of lightweight product structures, achieve lightweight product structures while ensuring the mechanical properties of product structures, and improve product design quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0025] Figure 1 It is a flow chart of the method for predicting mechanical properties and evaluating failure of dissimilar material connections of the present invention;

[0026] Figure 2 It is a simulation model of dissimilar material connection under Lsdyn in the method for predicting mechanical properties and failure evaluation of dissimilar material connection of the present invention;

[0027] Figure 3It is a mapping relationship model between the upper plate thickness, the lower plate thickness, the rivet diameter, the bonding thickness and the maximum peak force, the displacement corresponding to the maximum peak force, the fracture displacement, the optimal tangential load function index value, and the failure mode constructed by the radial basis neural network model in the method for predicting the mechanical properties of the connection of dissimilar materials of the present invention;

[0028] Figure 4 It is a comparison diagram of the experimental test force displacement curve and the simulation force displacement curve in the first embodiment of the method for predicting mechanical properties and failure evaluation of dissimilar material connection of the present invention;

[0029] Figure 5 It is a comparison diagram of the experimental test force displacement curve and the simulation force displacement curve in the second embodiment of the method for predicting mechanical properties and failure evaluation of dissimilar material connection of the present invention;

[0030] Figure 6 It is a comparison diagram of the experimental test force-displacement curve and the simulation force-displacement curve in Example 3 of the method for predicting mechanical properties and failure evaluation of dissimilar material connections of the present invention. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figure 1 , a method for predicting mechanical properties and failure evaluation of dissimilar material connections, comprising the following steps:

[0033] (1) The connection schemes with different upper plate thickness, lower plate thickness, rivet diameter, and adhesive thickness were designed through DOE experimental design. The force-displacement curve was obtained through tensile test, and the maximum peak force, displacement corresponding to the maximum peak force, fracture displacement, and failure mode were extracted. The failure mode included upper plate fracture, lower plate fracture, and rivet fracture.

[0034] (2) Construct a material constitutive model and establish a simulation model for the connection of dissimilar materials based on Lsdyn;

[0035] (3) Designing different tangential load function index values ​​through DOE experimental design schemes, taking the maximum peak force, the displacement corresponding to the maximum peak force, and the fracture displacement obtained in step (1) as input values ​​of the constitutive model, and starting a large number of simulations using the simulation model established in step (2), and obtaining the optimal tangential load function index values ​​under different DOE design schemes by comparing the force-displacement curves of the experimental test with the force-displacement curves obtained by simulation;

[0036] (4) A radial basis function neural network model is used to construct the mapping relationship between the upper plate thickness, lower plate thickness, rivet diameter, bonding thickness and maximum peak force, displacement corresponding to the maximum peak force, fracture displacement, optimal tangential load function index value, and failure mode;

[0037] (5) Based on the radial basis function neural network model, the maximum peak force, the displacement corresponding to the maximum peak force, the fracture displacement, the optimal tangential load function index value, and the failure mode under the connection scheme of fixed upper plate thickness, lower plate thickness, rivet diameter, and bonding thickness are calculated. Based on the connection simulation model of step (2), the maximum peak force, the displacement corresponding to the maximum peak force, the fracture displacement, and the optimal tangential load function index value obtained above are used as the material constitutive model parameter input, and the simulated force-displacement curve is calculated. Combined with the failure mode obtained by the radial basis function neural network model, the mechanical property prediction and failure evaluation of the connection of dissimilar materials can be realized.

[0038] Preferably, the material constitutive model relation in step (2) is:

[0039]

[0040]

[0041] f t :Real-time test force

[0042] f t Max : Maximum peak force

[0043] δ t :Real-time test displacement

[0044] δ t Max : Displacement corresponding to the maximum peak force

[0045] η Max : Damage measure, consistent with strain, i.e. δ t / δ t Max

[0046] ξ t : Reverse value, displacement corresponding to the maximum peak force / fracture displacement

[0047] x is the exponential value of the tangential load function.

[0048] See also Figure 2 and Figure 4 , Embodiment 1:

[0049] The upper plate 2 is made of HC340 steel with a thickness of 1.2 mm;

[0050] The lower plate 1 is made of aluminum 5182 and has a thickness of 1.5 mm;

[0051] Rivet 4 diameter 5mm;

[0052] No glue joint, the glue layer thickness is 0;

[0053] The upper plate 2 and the lower plate 1 at both ends are stretched outwards, the tensile test data are recorded, and the force displacement curve diagram of the experimental test is produced; the connection simulation model also gives the force displacement curve diagram;

[0054] Through the mechanical property prediction and failure evaluation method of the present invention, the maximum peak force obtained is 5111N, the displacement corresponding to the maximum peak force is 6mm, the fracture displacement is 15mm, the optimal tangential load function index value is 3.5, and the failure mode is lower plate fracture.

[0055] See also Figure 2 and Figure 5 , Embodiment 2:

[0056] The upper plate 2 is made of HC340 steel with a thickness of 1.5 mm;

[0057] The lower plate 1 is made of aluminum 5182 and has a thickness of 1.5 mm;

[0058] Rivet 4 diameter 5mm;

[0059] No glue joint, the glue layer thickness is 0;

[0060] Through the mechanical property prediction and failure evaluation method of the present invention, the maximum peak force obtained is 5645N, the displacement corresponding to the maximum peak force is 6mm, the fracture displacement is 12mm, the optimal tangential load function index value is 3, and the failure mode is the fracture of the lower plate.

[0061] See also Figure 2 and Figure 6 , Embodiment 3:

[0062] The upper plate 2 is made of HC340 steel with a thickness of 2 mm;

[0063] The lower plate 1 is made of aluminum 5182 and has a thickness of 1.5 mm;

[0064] Rivet 4 diameter 5mm;

[0065] No glue joint, the glue layer thickness is 0;

[0066] Through the mechanical property prediction and failure evaluation method of the present invention, the maximum peak force obtained is 5556N, the displacement corresponding to the maximum peak force is 5.5mm, the fracture displacement is 8mm, the optimal tangential load function index value is 3, and the plate fracture is in the failure mode.

[0067] The method for predicting the mechanical properties and failure evaluation of the connection of dissimilar materials of the present invention establishes a model, compares the force-displacement curve diagram obtained by experimental testing with the force-displacement curve diagram of the simulation model, and performs lightweight connection design without failing the connection. This can assist in the design of lightweight product structures, achieve lightweight product structures while ensuring the mechanical properties of the product structures, and improve product design quality.

Claims

1. A method for predicting mechanical properties and evaluating failure of dissimilar material connections, characterized by: The steps include: (1) The connection schemes with different upper plate thickness, lower plate thickness, rivet diameter, and adhesive thickness were designed through DOE experimental design. The force-displacement curve was obtained through tensile test, and the maximum peak force, displacement corresponding to the maximum peak force, fracture displacement, and failure mode were extracted. The failure mode included upper plate fracture, lower plate fracture, and rivet fracture. (2) Construct a material constitutive model and establish a simulation model for the connection of dissimilar materials based on Lsdyn; (3) Designing different tangential load function index values ​​through DOE experimental design schemes, taking the maximum peak force, the displacement corresponding to the maximum peak force, and the fracture displacement obtained in step (1) as input values ​​of the constitutive model, and starting a large number of simulations using the simulation model established in step (2), and obtaining the optimal tangential load function index values ​​under different DOE design schemes by comparing the force-displacement curves of the experimental test with the force-displacement curves obtained by simulation; (4) A radial basis function neural network model is used to construct the mapping relationship between the upper plate thickness, lower plate thickness, rivet diameter, bonding thickness and maximum peak force, displacement corresponding to the maximum peak force, fracture displacement, optimal tangential load function index value, and failure mode; (5) Based on the radial basis function neural network model, the maximum peak force, the displacement corresponding to the maximum peak force, the fracture displacement, the optimal tangential load function index value, and the failure mode under the connection scheme of fixing the upper plate thickness, the lower plate thickness, the rivet diameter, and the bonding thickness are calculated. Based on the connection simulation model of step (2), the maximum peak force, the displacement corresponding to the maximum peak force, the fracture displacement, and the optimal tangential load function index value obtained above are used as material constitutive model parameter inputs, and the simulated force-displacement curve is calculated and obtained. Combined with the failure mode obtained by the radial basis function neural network model, the mechanical property prediction and failure evaluation of the connection of dissimilar materials can be realized; The material constitutive model relationship in step (2) is: f t :Real-time test force f t Max : Maximum peak force δ t :Real-time test displacement δ t Max : Displacement corresponding to the maximum peak force η Max : Damage metric value ξ t : Reverse value, displacement corresponding to the maximum peak force / fracture displacement x is the exponential value of the tangential load function.

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