Design method of additive manufacturing lattice structure

Abstract

The invention relates to the field of lattice structure design, and discloses a design method of an additive manufacturing lattice structure, which is characterized in that envelope line drawing and the following steps in the existing design are changed into drawing of a Wv / Es-sigma / Es diagram of each structure, and practical application parameters (energy absorption U and peak stress sigma p) are substituted into the diagram to directly obtain a structure type and a strut inclination angle; the rod diameter d can be obtained through the two simple equations, and the design of the structure is completed, so that repeated drawing of a complex envelope diagram and use of the complex equations during subsequent calculation of the rod diameter d are fundamentally avoided, the whole lattice structure design process is simpler and more convenient, and the practical application potential is achieved.

Description

Technical Field

[0001] The present invention relates to the field of lattice structure design, and in particular to a design method for an additively manufactured lattice structure. Background Art

[0002] The lattice structure is considered to be the most promising porous structure due to its lightweight, ability to bear complex loads and energy absorption characteristics. Many studies have shown that the lattice structure can have excellent energy absorption performance by changing the structural parameters. Therefore, it is extremely valuable to propose a systematic method for the design of lattice structures. The existing lattice structure design technology is mainly forward design. By pre-analyzing the application stress conditions of the structure, the finite element analysis software (ABAQUS software) is used to increase or decrease the material of the initial structure, and multiple iterations are performed to obtain the final lattice structure that meets the application requirements. This design process is time-consuming and labor-intensive, and due to the complexity of the actual stress conditions of the structure and the incomplete analysis of the initial stress conditions, it is very likely that the lattice structure obtained by iteration cannot meet the actual application requirements. The prior art proposes a lattice structure design method based on an energy absorption diagram. The specific design steps are as follows: Figure 3 As shown, it is determined by pre-determining the structural energy absorption U and peak stress σ p , the contact area Ac of the lattice structure and the number of structural layers nl. The ratio of peak stress to Young's modulus is obtained by calculation, and two H values ​​are selected and calculated according to the following formula: Figure 3 The formula in the Wv / Es-σ / Es diagram is used to draw the envelope, obtain two intersection values, calculate Wv, and then obtain two new H values; substitute it into the formula as follows Figure 4 In the formula, we get the new envelope and intersection point, repeat the above process, and make two H values ​​converge; finally, according to Figure 5 and Figure 6 The rod diameter d and unit lattice density are calculated by the formula in the above formula to complete the lattice structure design. The prior art method has the problem of drawing envelopes in the lattice design process. The equations are complex, the calculations are difficult, and the applicability to different structures is different. Figure 3 In step (6), since the H value selected previously is not based on any evidence, multiple calculation iterations are required to obtain a unique H value. Each iteration requires redrawing the envelope, which is a cumbersome process. Finally, in order to obtain the rod diameter d and the unit structure density, a very complex equation is required ( Figure 6 ), further increasing the difficulty of calculation and making this structural design method almost non-existent in practical application. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a design method for an additively manufactured lattice structure to address the deficiencies of the prior art.

[0004] The object of the present invention is achieved through the following technical solution: A design method for additive manufacturing lattice structure, comprising the following design steps:

[0005] S1. Input parameters are the structure bottom length L, the energy absorption required by the application Wvmax and the specified peak stress σ p ;

[0006] S2. Substitute the input parameters into the relationship diagram composed of the empirical shoulder line equations of various structures established in the previous experiments. Assuming that the parameters Wv / Es is 0.00007 and σ / Es is 0.0002, the structural parameters are represented as a point in the diagram. Using the point-to-line distance formula Calculate the distance between the point and the straight line, and determine which structure should be selected based on the distance. At this point, the required structure type and the inclination angle of the pillars have been determined;

[0007] In step S2, the structural type and the inclination angle are known, that is, the structural deformation mechanism is known to be stretch-dominated or bending-dominated, the inclination angle is greater than 45 degrees for stretch-dominated, and the inclination angle is equal to or less than 45 degrees for bending-dominated;

[0008] When the structure is tension-dominated, the formula is used The relative density of the unit structure is calculated, and the relative density of the structure is the ratio of the volume of the support rod to the volume of the cuboid surrounded by the support rod. From this, the total volume of the support rod can be obtained. The structural type is known, that is, the number and length of the support rods are known. According to the cylinder volume calculation formula, the final required support rod diameter d can be obtained, and the structural design is completed;

[0009] When the structure is bending dominated, the formula is used Calculation is performed. Since the structure type is known, that is, the height H of the structure is constant, the platform stress σ m (for σ p ) is known, b is a geometric constant related to the structure. Through previous experiments, the b value of each structure is known, from which the required pillar rod diameter can be directly obtained. The structure type, pillar rod diameter and overall size required for the lattice design have been fully obtained;

[0010] Among them, σ pe is the peak stress of the elastic section of the structural stress-strain curve, σ s is the yield stress of the base material, C is a geometric constant related to the structure. According to previous experiments, the C value corresponding to each structure has been calculated, σ m is the platform stress, b is the geometric constant related to the structure, and H is the height of the unit structure.

[0011] A design method for an additive manufacturing lattice structure includes the following design steps:

[0012] S1. Input parameters are the structure bottom length L, the specified peak stress σp and the total structural energy absorption U;

[0013] S2, input parameter peak stress σ p Substitute the shoulder line equation of each structure established in the previous experiment to obtain the energy absorption amount Wvmax corresponding to each structure. Substitute it into the formula U=Wvmax*H*Ac*n, where H is the known height of the structure. Therefore, the total energy absorption value U1 corresponding to the structure can be obtained. Compare U1 with the input parameter U, and select the structure with the smallest |U1-U| as the adaptive structure type.

[0014] In step S2, the structural type and the inclination angle are known, that is, the structural deformation mechanism is known to be stretch-dominated or bending-dominated, the inclination angle is greater than 45 degrees for stretch-dominated, and the inclination angle is equal to or less than 45 degrees for bending-dominated;

[0015] When the structure is tension-dominated, the formula is used The relative density of the unit structure is calculated, and the relative density of the structure is the ratio of the volume of the support rod to the volume of the cuboid surrounded by the support rod. From this, the total volume of the support rod can be obtained. The structural type is known, that is, the number and length of the support rods are known. According to the cylinder volume calculation formula, the final required support rod diameter d can be obtained, and the structural design is completed;

[0016] When the structure is bending dominated, the formula is used Calculation is performed. Since the structure type is known, that is, the height H of the structure is constant, the platform stress σ m (for σ p ) is known, b is a geometric constant related to the structure. Through previous experiments, the b value of each structure is known, from which the required pillar rod diameter can be directly obtained. The structure type, pillar rod diameter and overall size required for the lattice design have been fully obtained;

[0017] Among them, U is the total energy absorption of the structure, Wvmax is the maximum energy absorption of the structure, H is the height of the unit structure, Ac is the stress area of ​​the structure, and n is the number of structural layers.

[0018] The beneficial effects of the present invention are:

[0019] Improvements were made to the complex equations and cumbersome processes of the existing design methods, and the previous experimental data were integrated and processed as a database. In the subsequent lattice structure design, after entering the relevant restriction parameters, the structural shoulder line equation in the database was called, and the fitness was determined, and the structure with the highest fitness was selected as the predetermined structure. Subsequently, different formulas were selected to calculate the support rod diameter d according to the deformation mechanism of the predetermined structure (stretching-dominated or bending-dominated). As a result, the entire lattice design process has been simplified to a considerable extent by removing complex formulas and cumbersome iterative processes, making it valuable for engineering applications to a certain extent, and providing a design basis for matching structural lightweight and structural strength in engineering design. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A design method step diagram of a design method for an additive manufacturing lattice structure of the present invention;

[0021] Figure 2 A relationship diagram consisting of the shoulder line equations of various structures in a design method for additive manufacturing lattice structure of the present invention;

[0022] Figure 3 It is a design step diagram of the prior art;

[0023] Figure 4 Formula 1 used in the prior art;

[0024] Figure 5 Formula 2 used in the prior art;

[0025] Figure 6 Formula 3 used in the prior art; DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0027] like Figure 1 As shown, a design method for additive manufacturing lattice structure is divided into two design routes according to different input parameters;

[0028] The first design route includes the following design steps:

[0029] S1. Input parameters are the structure bottom length L, the energy absorption required by the application Wvmax and the specified peak stress σ p ;

[0030] S2. Substitute the input parameters into the relationship diagram composed of the empirical shoulder line equations of various structures established in the previous experiments, such as Figure 2As shown in the figure, assuming that the parameters Wv / Es is 0.00007 and σ / Es is 0.0002, the structural parameters are represented by 1 point in the figure, and the distance formula between the point and the straight line is used. Calculate the distance between the point and the line, and determine which structure should be selected based on the distance (the smaller the distance, the more the structure meets the application requirements). At this point, the required structure type and support inclination angle have been determined;

[0031] In step S2, the structural type and the inclination angle are known, that is, the structural deformation mechanism is known to be stretch-dominated or bending-dominated, the inclination angle is greater than 45 degrees for stretch-dominated, and the inclination angle is equal to or less than 45 degrees for bending-dominated;

[0032] When the structure is tension-dominated, the formula is used The relative density of the unit structure is calculated, and the relative density of the structure is the ratio of the volume of the support rod to the volume of the cuboid surrounded by the support rod. From this, the total volume of the support rod can be obtained. The structural type is known, that is, the number and length of the support rods are known. According to the cylinder volume calculation formula, the final required support rod diameter d can be obtained, and the structural design is completed;

[0033] When the structure is bending dominated, the formula is used Calculation is performed. Since the structure type is known, that is, the height H of the structure is constant, the platform stress σ m (for σ p ) is known, b is a geometric constant related to the structure. Through previous experiments, the b value of each structure is known, from which the required pillar rod diameter can be directly obtained. The structure type, pillar rod diameter and overall size required for the lattice design have been fully obtained;

[0034] Among them, σ pe is the peak stress of the elastic section of the structural stress-strain curve, σ s is the yield stress of the base material, C is a geometric constant related to the structure. According to previous experiments, the C value corresponding to each structure has been calculated, σ m is the platform stress, b is the geometric constant related to the structure, and H is the height of the unit structure.

[0035] The second design route includes the following design steps:

[0036] S1. Input parameters are the structure bottom length L, the specified peak stress σ p and the total structural energy absorption U;

[0037] S2, input parameter peak stress σ pSubstitute the shoulder line equation of each structure established in the previous experiment to obtain the energy absorption amount Wvmax corresponding to each structure. Substitute it into the formula U=Wvmax*H*Ac*n, where H is the known height of the structure. Therefore, the total energy absorption value U1 corresponding to the structure can be obtained. Compare U1 with the input parameter U, and select the structure with the smallest |U1-U| as the adaptive structure type.

[0038] In step S2, the structural type and the inclination angle are known, that is, the structural deformation mechanism is known to be stretch-dominated or bending-dominated, the inclination angle is greater than 45 degrees for stretch-dominated, and the inclination angle is equal to or less than 45 degrees for bending-dominated;

[0039] When the structure is tension-dominated, the formula is used The relative density of the unit structure is calculated, and the relative density of the structure is the ratio of the volume of the support rod to the volume of the cuboid surrounded by the support rod. From this, the total volume of the support rod can be obtained. The structural type is known, that is, the number and length of the support rods are known. According to the cylinder volume calculation formula, the final required support rod diameter d can be obtained, and the structural design is completed;

[0040] When the structure is bending dominated, the formula is used Calculation is performed. Since the structure type is known, that is, the height H of the structure is constant, the platform stress σ m (for σ p ) is known, b is a geometric constant related to the structure. Through previous experiments, the b value of each structure is known, from which the required pillar rod diameter can be directly obtained. The structure type, pillar rod diameter and overall size required for the lattice design have been fully obtained;

[0041] Among them, U is the total energy absorption of the structure, Wvmax is the maximum energy absorption of the structure, H is the height of the unit structure, Ac is the stress area of ​​the structure, and n is the number of structural layers.

[0042] In summary, all the structure-related data (stress and strain, energy absorption, structural dimensions, etc.) obtained from previous experiments are integrated into a database. By preliminarily processing the input limiting parameters and bringing the processed data into the structural shoulder line equation in the database, the degree of fit between the specific structure and the input parameters is obtained, thereby selecting the structural type that best matches the application requirements.

[0043] In order to further determine the key parameters (pillar rod diameter) in the structural design, it is first necessary to select different calculation formulas according to the selected structural deformation mechanism. The tensile dominant type is The bending dominant type is U = Wvmax*H*Ac*n; the pillar rod diameter d or the relative density of the structure related to d is directly calculated through the formula, and then the pillar rod diameter d is calculated through the pillar diameter and volume formula. Finally, the entire lattice structure design is completed, and a structure that meets the input requirements is obtained.

[0044] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "two ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; and it is known to those skilled in the art that the beneficial effects to be achieved by the present invention are only to achieve better beneficial effects under specific circumstances compared with the current implementation schemes in the prior art, rather than to directly achieve the best use effect in the industry.

[0045] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A design method for an additive manufacturing lattice structure, characterized in that: The design steps include: S1. Input parameters are the structure bottom length L, application required energy absorption Wvmax and specified peak stress σ p ; S2. Substitute the input parameters into the relationship diagram composed of the empirical shoulder line equations of various structures established in the previous experiments. Assuming that the parameters Wv / Es is 0.00007 and σ / Es is 0.0002, the structural parameters are represented as a point in the diagram. Using the point-to-line distance formula Calculate the distance between the point and the straight line, and determine which structure should be selected based on the distance. At this point, the required structure type and the inclination angle of the pillars have been determined; In step S2, the structural type and the inclination angle are known, that is, the structural deformation mechanism is known to be stretch-dominated or bending-dominated, the inclination angle is greater than 45 degrees for stretch-dominated, and the inclination angle is equal to or less than 45 degrees for bending-dominated; When the structure is tension-dominated, the formula is used The relative density of the unit structure is calculated, and the relative density of the structure is the ratio of the volume of the support rod to the volume of the cuboid surrounded by the support rod. From this, the total volume of the support rod can be obtained. The structural type is known, that is, the number and length of the support rods are known. According to the cylinder volume calculation formula, the final required support rod diameter d can be obtained, and the structural design is completed; When the structure is bending dominated, the formula is used Calculation is performed. Since the structure type is known, that is, the height H of the structure is constant, the platform stress σ m (for σ p ) is known, b is a geometric constant related to the structure. Through previous experiments, the b value of each structure is known, from which the required pillar rod diameter can be directly obtained. The structure type, pillar rod diameter and overall size required for the lattice design have been fully obtained; Among them, σ pe is the peak stress of the elastic section of the structural stress-strain curve, σ s is the yield stress of the base material, C is a geometric constant related to the structure. According to previous experiments, the C value corresponding to each structure has been calculated, σ m is the platform stress, b is the geometric constant related to the structure, and H is the unit structure height.

2. A design method for an additive manufacturing lattice structure, characterized in that: The design steps include: S1. Input parameters are the structure bottom length L, the specified peak stress σ p and the total structural energy absorption U; S2, input parameter peak stress σ p Substitute the shoulder line equation of each structure established in the previous experiment to obtain the energy absorption amount Wvmax corresponding to each structure. Substitute it into the formula U=Wvmax*H*Ac*n, where H is the known height of the structure. Therefore, the total energy absorption value U1 corresponding to the structure can be obtained. Compare U1 with the input parameter U, and select the structure with the smallest |U1-U| as the adaptive structure type. In step S2, the structural type and the inclination angle are known, that is, the structural deformation mechanism is known to be stretch-dominated or bending-dominated, the inclination angle is greater than 45 degrees for stretch-dominated, and the inclination angle is equal to or less than 45 degrees for bending-dominated; When the structure is tension-dominated, the formula is used The relative density of the unit structure is calculated, and the relative density of the structure is the ratio of the volume of the support rod to the volume of the cuboid surrounded by the support rod. From this, the total volume of the support rod can be obtained. The structural type is known, that is, the number and length of the support rods are known. According to the cylinder volume calculation formula, the final required support rod diameter d can be obtained, and the structural design is completed; When the structure is bending dominated, the formula is used Calculation is performed. Since the structure type is known, that is, the height H of the structure is constant, the platform stress σ m (for σ p ) is known, b is a geometric constant related to the structure. Through previous experiments, the b value of each structure is known, from which the required pillar rod diameter can be directly obtained. The structure type, pillar rod diameter and overall size required for the lattice design have been fully obtained; Among them, U is the total energy absorption of the structure, Wvmax is the maximum energy absorption of the structure, H is the height of the unit structure, Ac is the stress area of ​​the structure, and n is the number of structural layers.

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