Finite element drop analysis optimization method, device and medium based on numerical calculation

Abstract

This application is a finite element drop analysis optimization method, device, and medium based on numerical calculation. In response to the practical problems faced by enterprises that existing methods have failed to fully solve, a finite element drop analysis optimization method based on numerical calculation is provided, including: converting the drop height into an equivalent initial velocity; generating a collision coordinate system based on the drop direction, and then generating a floor model based on the generated collision coordinate system; calculating the effective duration by measuring the time it takes for the reaction force of the floor model surface nodes to decrease to 0 or reach a set threshold; and simulating the product's drop process by inputting a three-dimensional model of the product and the drop height into a set finite element analysis model to obtain the drop dynamic results and maximum stress cloud diagram. By simplifying and optimizing the finite element model and calculation process, enterprises can conduct virtual drop tests during the R&D stage, avoiding the time waste and blind production caused by traditional physical testing, and improving the accuracy and efficiency of product design.

Description

Technical Field

[0001] The present application relates to the field of product drop analysis, and in particular to a finite element drop analysis optimization method, device, and medium based on numerical calculation. Background Art

[0002] In modern manufacturing, product drop testing is an important means of verifying a product's durability, reliability, and ability to withstand external shocks during transportation or use. Currently, many companies still rely on traditional physical experimental methods for product research and development and testing. This physical drop test can provide a certain degree of reliability verification for products, but it has some significant drawbacks. In particular, during product development, the limitations of physical testing often lead to extended development cycles and inadequate test results. Adequate digital verification is often not performed in the early stages of product design, resulting in modifications and adjustments only being made when problems arise during the product trial production phase. This traditional method not only prolongs the product development cycle and increases production costs, but also often results in design flaws that cannot be predicted and resolved in a timely manner.

[0003] Finite element analysis (FEA), as a powerful numerical calculation method, has been widely used in product structural analysis, mechanical property verification, and other aspects. By simulating the stress state, deformation, and possible damage of an object during a fall, finite element analysis can predict in advance the performance of a product during an actual fall. Existing finite element analysis methods have many operational difficulties when applied to fall analysis, especially for companies with relatively weak engineering and technical capabilities. These difficulties are more significant. A commonly used method is to use mature finite element analysis tools to perform a detailed segmentation of the fall scenario and simulate the dynamic behavior of the product during the fall in order to verify the reliability of the product. Although this method can theoretically provide more accurate simulation results, its application faces two core problems that affect the implementation effect of the company in actual research and development.

[0004] Therefore, how to efficiently and accurately perform drop analysis while reasonably estimating simulation calculation time has become a core issue facing companies. The operational complexity and uncertainty of traditional finite element analysis tools make it difficult for companies to fully utilize digital technology for drop testing, which in turn affects the speed and quality of product development. Summary of the Invention

[0005] In view of the limitations of existing physical testing and digital drop analysis tools, which have not yet completely solved the practical problems faced by enterprises, the present invention proposes a finite element drop analysis optimization method, device and medium based on numerical calculation. By simplifying and optimizing the finite element model and calculation process, enterprises can perform virtual drop tests in the R&D stage, avoiding the time waste and blind production caused by traditional physical testing, and improving the accuracy and efficiency of product design.

[0006] The present invention provides a finite element drop analysis optimization method based on numerical calculation, comprising the following steps:

[0007] S1, convert the drop height into equivalent initial velocity; the purpose of this step is to simplify the calculation process and shorten the calculation time;

[0008] S2, based on the results of S1 and the contact between the product and the ground, generates a collision coordinate system according to the falling direction, and then generates a floor model based on the generated collision coordinate system;

[0009] S3, by measuring the time it takes for the reaction force of the floor model surface nodes to decrease to 0 or reach a set threshold, to calculate the effective duration. The effective duration refers to the time from the product contacting the floor model to the rebound. The set finite element analysis model is then obtained.

[0010] S4, by inputting the product 3D model and drop height into the set finite element analysis model, simulates the product's drop process and obtains the drop dynamic results and maximum stress cloud map.

[0011] Furthermore, the formula for converting the drop height into the equivalent initial velocity is:

[0012]

[0013] Where: v is the velocity of the object when it touches the ground (unit: m / s), g is the acceleration due to gravity (take ), h is the falling height of the model (unit: m).

[0014] In traditional drop analysis simulations, the product starts to fall freely from a standstill, and engineers need to set the initial height of the object and the effect of gravity to simulate its falling process. Each drop simulation requires step-by-step calculation of data such as displacement, velocity, and acceleration at each moment, which is time-consuming and computationally complex. The present application can save computing resources by converting the drop height into an equivalent initial velocity. Specifically, the given drop height h is directly converted into the initial velocity v, which can skip the long free fall simulation starting from zero velocity and perform impact analysis directly at the initial velocity. This not only simplifies the calculation steps, but also effectively prevents the situation where a lot of computing time is wasted in dynamic calculations due to linear movement of the finite element model; and the calculation starts in the form of contact, which is conducive to predicting the collision time of the model when it falls, that is, the time interval from the model contacting the floor model to the first rebound completely leaving the floor model. By predicting the collision time, the calculation time can be further shortened, the calculation efficiency can be improved, and the situation where the fall time is difficult to estimate and requires repeated debugging can be avoided.

[0015] Furthermore, the specific process of S2 includes:

[0016] S2.1. Analyze all nodes of the product's 3D model in the global coordinate system to determine the extreme position point along the falling direction and set this extreme position point as the collision point. The global coordinate system refers to the original coordinate system used when drawing the product's 3D model.

[0017] S2.2, set the collision point as the origin of the collision coordinate system, set the falling direction as a new axis of the collision coordinate system, use the determined new axis as the normal vector of the plane where the other two new axes are located, and then determine the directions of the other two new axes;

[0018] S2.3, calculating the size of the floor model in the collision coordinate system according to the collision coordinate system to form a floor model;

[0019] S2.4. Construct a rotating coordinate system at the geometric center of gravity of the product's 3D model. Adjust the drop angle of the product model by rotating the coordinate system, and associate the rotated floor model with the collision coordinate system to ensure that its contact surface accurately adapts to the product's collision conditions.

[0020] When most companies perform finite element drop analysis, they typically only provide a 3D model of the product, omitting the floor model involved in the drop process. The floor model serves more than just a "hard" contact surface; it also determines the rebound, deformation, and impact force transfer of the product after a drop. Therefore, accurately simulating the contact and collision between the floor model and the product is crucial for accurate drop analysis.

[0021] The core of the collision coordinate system is to accurately locate the collision point and establish a new reference system that meets the needs of drop analysis by redefining the coordinate axes.

[0022] Furthermore, the specific process of step S2.3 is as follows:

[0023] S2.3.1, determine the thickness of the floor model based on the set value of the fall direction;

[0024] S2.3.2. Determine the length and width of the floor model using the calculation results for the X and Y axes of the collision coordinate system:

[0025] Detect the coordinate values of all nodes of the product model in the X-axis direction of the global coordinate system, and determine the maximum span of the product model in the global X-axis direction by the difference between the maximum and minimum values. With the collision coordinate point as the center, extend the length of the floor model in the positive and negative directions of the X-axis of the collision coordinate system by integer multiples of the maximum span respectively.

[0026] Detect the coordinate values of all nodes of the product model in the Y-axis direction of the global coordinate system, and determine the maximum span of the product model in the global Y-axis direction by the difference between the maximum and minimum values. With the collision coordinate point as the center, extend the integer multiples of the maximum span in the positive and negative directions of the Y-axis of the collision coordinate system to form the length of the floor model.

[0027] Furthermore, the specific process of constructing the rotating coordinate system in S2.4 includes:

[0028] The input value of the rotation matrix is the rotation angle around the X, Y, and Z axes of the global coordinate system. 、 、 ; The rotation matrix can be expressed as:

[0029]

[0030] Among them, the rotation matrices around the X, Y, and Z axes are:

[0031]

[0032] Where R is the rotation matrix, is the rotation matrix around the X axis, is the rotation matrix around the Y axis, is the rotation matrix around the Z axis.

[0033] By multiplying the above matrices, the initial plane of the floor model can be rotated to match the specified drop angle. This rotated floor model is then associated with the collision coordinate system, ensuring its contact surface precisely adapts to the product's collision conditions while maintaining the flexibility of dynamic adjustment. This approach effectively reduces the complexity of manual angle adjustment, improving operational efficiency and the accuracy of analysis results. By using reverse engineering, the drop direction can be altered by changing the floor model generation direction, achieving the same angle change.

[0034] Furthermore, the calculation formula for the effective duration is:

[0035]

[0036] Where, is the normal reaction force of the i-th contact node on the floor model surface at time t; N represents the total number of contact nodes on the floor model surface; is the set reaction force threshold; The duration of the contact between the model and the floor model, that is, the time from the model contacting the ground to the completion of the rebound.

[0037] In drop analysis, accurately estimating the time from when a model contacts the floor to when it rebounds is a critical step, as this time period determines the effective computational time of the solution. Therefore, by estimating and controlling the time from when a model falls to when it rebounds, computational efficiency can be significantly improved and inefficient calculations can be reduced.

[0038] In the finite element model, nodes on the floor surface contact the model and exert a reaction force. According to physics principles, when the model contacts the floor and begins to rebound, the reaction force gradually decreases. By monitoring the reaction force at each node on the floor surface in real time, the contact state and rebound process of the model and the floor can be inferred.

[0039] When the reaction force gradually decreases to near zero, it indicates that the contact between the model and the floor model has gradually ended, and the rebound process has basically completed. To determine the effective calculation time, you can set a threshold. When the reaction force of all nodes on the floor model surface is less than this threshold, the system will determine that the model has completed contact and has begun to rebound, thus terminating the solution process.

[0040] Furthermore, calculating the effective duration includes the following steps:

[0041] S3.1, extract reaction force data: monitor the reaction forces of all nodes on the floor model surface in real time and obtain the reaction force values of the nodes at each time step;

[0042] S3.2, determine the zero value state of the reaction force: set a threshold. When the reaction force values of all the surface nodes of the floor model are lower than the threshold, it is considered that the model has completed contact with the floor model.

[0043] S3.3, determine the end time of contact: When the reaction forces of all nodes are close to zero, calculate the end time of contact between the model and the floor model, marking the beginning of rebound.

[0044] S3.4, breakpoint command control: Based on the calculated contact end time, if the product rebounds from the ground during the solution process, a stop command is issued to stop the solution process and eliminate the remaining invalid calculation time.

[0045] Furthermore, the specific process of step S4 is as follows:

[0046] S4.1, obtaining relative displacement data based on the node displacement data of the product model recorded during the solution of the finite element analysis model, wherein the node displacement data describes the motion state of each node in units of time steps;

[0047] S4.2, by adding the relative displacement data to the original coordinates to calculate the absolute position of the node, and then reconstruct the instantaneous geometric state of the product model, that is, the geometric state at different time frames;

[0048] S4.3, connect the geometric states in different time frames in chronological order to form a complete dynamic sequence;

[0049] S4.4, adjust the time axis mapping to be consistent with the simulation time step;

[0050] S4.5, obtaining the drop dynamic results of the product model at a fixed viewing angle;

[0051] S4.6, traverse the stress values of the product model, obtain the time frame corresponding to the maximum stress value as the key frame, extract the stress distribution data corresponding to the key frame to generate a maximum stress cloud map, which intuitively presents the stress distribution status on the surface and inside of the model in the form of color gradient.

[0052] In the post-processing stage of finite element drop analysis, how to intuitively display the falling state of the model is the core content of the entire analysis process. The display effect directly affects the efficiency of the interpretation of the results and subsequent design optimization. In order to restore the dynamic behavior of the model as accurately as possible and highlight the key stress state, this application combines the two methods of drop animation and maximum stress cloud map. Through the organic combination of dynamic and static display, the response state of the model during the drop process is fully presented. The implementation of this technical solution involves multiple key links such as data extraction, algorithm processing and visual rendering, covering the entire process from physical simulation results to visual output.

[0053] A finite element drop analysis optimization device based on numerical calculation, comprising:

[0054] Drop conversion module, used to convert drop height into equivalent initial velocity;

[0055] a fall direction adjustment module connected to the conversion module, generating a collision coordinate system according to the fall direction based on the result of the fall conversion module and the contact situation between the product and the ground, and then generating a floor model based on the generated collision coordinate system;

[0056] A drop time identification module is connected to the drop direction adjustment module. Based on the results of the drop direction adjustment module, the module calculates the effective duration by measuring the time it takes for the reaction force of the nodes on the surface of the floor model to decrease to zero or reach a set threshold. The effective duration is the time from the product contacting the floor model to the rebound. The module then forms a pre-set finite element analysis model.

[0057] The drop solution module is connected to the drop time identification module and is used to simulate the product's drop process by inputting the product's three-dimensional model and drop height into the set finite element analysis model to obtain the drop dynamic results and maximum stress cloud map.

[0058] A computer-readable medium includes a memory and one or more processors, wherein the memory stores executable code, and when the one or more processors execute the executable code, the one or more processors are used to implement the finite element drop analysis optimization method based on numerical calculation.

[0059] Beneficial effects: This application is a finite element drop analysis optimization method, device and medium based on numerical calculation. The drop height is converted into an equivalent initial velocity, which effectively shortens the model calculation time, automatically generates the collision coordinate system and floor model, improves the calculation accuracy of the effective time, significantly improves the calculation efficiency, and reduces invalid calculations. By simplifying and optimizing the finite element model and calculation process, enterprises can conduct virtual drop tests in the R&D stage, avoid the time waste and blind production caused by traditional physical testing, and improve the accuracy and efficiency of product design. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 The diagram is a three-dimensional structural diagram of a falling product with a collision coordinate system;

[0061] Figure 2 Structural diagrams generated for the collision coordinate system and floor model;

[0062] Figure 3 This is a schematic diagram of the structure before the rotation coordinate system is adjusted;

[0063] Figure 4 This is a schematic diagram of the structure after adjusting the product drop angle by rotating the coordinate system;

[0064] Figure 5 The maximum stress contour diagram of the application example;

[0065] Figure 6 This is a flow chart of Example 1. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0067] Example 1

[0068] A finite element drop analysis optimization method based on numerical calculation, the flow chart is as follows Figure 6 As shown, the following steps are included:

[0069] S1, convert the drop height into equivalent initial velocity; the purpose of this step is to simplify the calculation process and shorten the calculation time; the formula for converting the drop height into equivalent initial velocity is:

[0070]

[0071] in: v is the speed of the object when it hits the ground (unit: m / s), g is the acceleration due to gravity (take ), h is the drop height of the model (unit: m).

[0072] S2, based on the results of S1 and the contact situation between the product and the ground, generates a collision coordinate system according to the falling direction, and then generates a floor model based on the generated collision coordinate system. The specific process includes:

[0073] S2.1, by analyzing all nodes of the product's three-dimensional model in the global coordinate system, determine the extreme position point along the falling direction and set the extreme position point as the collision point;

[0074] When the falling direction is a certain axis in the global coordinate system (for example, the -Z axis), it is necessary to retrieve the coordinate values of this axis (for example, the -Z axis) of all nodes in the global coordinate system, and select the point with the largest absolute value of the coordinate value of this axis (for example, the -Z axis) as the collision point, that is, .

[0075] S2.2 sets the collision point as the origin of the collision coordinate system, the drop direction as a new axis of the collision coordinate system, and uses the determined new axis as the normal vector of the plane containing the other two new axes to determine the directions of the other two new axes. This collision point represents the first point of contact between the model and the impact surface in the drop direction and is the core basis for defining the new coordinate system. After the collision point is determined, a new collision coordinate system is generated. The origin of the collision coordinate system is the location of the aforementioned collision point. The direction of the new axis of the collision coordinate system (for example, the -Z axis of the collision coordinate system) is consistent with the drop direction, that is, it points to the axial direction of the global coordinate system (for example, the -Z axis). The new collision coordinate system's XY plane is perpendicular to this -Z axis and is defined by the plane's normal vector at the collision point. In this way, the three coordinate axes (X, Y, and Z) of the collision coordinate system are redefined based on the collision point and drop direction.

[0076] S2.3, calculate the size of the floor model in the collision coordinate system based on the collision coordinate system to form the floor model; the specific process is as follows:

[0077] S2.3.1, determine the thickness of the floor model based on the set value of the fall direction;

[0078] S2.3.2. Determine the length and width of the floor model using the calculation results for the X and Y axes of the collision coordinate system:

[0079] Detect the coordinate values of all nodes of the product model in the X-axis direction of the global coordinate system, and determine the maximum span of the product model in the global X-axis direction by the difference between the maximum and minimum values. With the collision coordinate point as the center, extend the length of the floor model in the positive and negative directions of the X-axis of the collision coordinate system by integer multiples of the maximum span respectively.

[0080] Detect the coordinate values of all nodes of the product model in the Y-axis direction of the global coordinate system, and determine the maximum span of the product model in the global Y-axis direction by the difference between the maximum and minimum values. With the collision coordinate point as the center, extend the integer multiples of the maximum span in the positive and negative directions of the Y-axis of the collision coordinate system to form the length of the floor model.

[0081] When the drop axis is the -Z axis, the specific algorithm model and formula are as follows:

[0082] 1. Assume that the node set of the 3D model is ,node The global coordinates of x i ,y i , z i );

[0083] 2. The falling direction is the -Z axis of the global coordinate system. All nodes with negative values in the Z axis direction of the global coordinate system are retrieved. The -Z axis coordinate of the collision point P based on the global coordinate system is , the corresponding node coordinates are ( x p ,y p , z p );

[0084] 3. The origin of the collision coordinate system is O = ( x p ,y p , z p ).

[0085] 4. The new -Z axis of the collision coordinate system is the direction of the fall (here, the global -Z direction is used as an example). The new XY plane is defined by the origin O and its plane normal vector:

[0086] In the global coordinate system, it is represented as n XY =(0,0,-1) .

[0087] During this phase, the algorithm's core task is to automatically generate a collision coordinate system based on the model's fall direction, enabling precise switching of coordinate systems. By traversing the model's node data, the system quickly determines the collision point and its corresponding spatial location, using this as a reference to redefine the coordinate axes. This process simplifies the floor model generation logic and lays a precise mathematical and geometric foundation for subsequent fall analysis.

[0088] The process of generating a floor model based on the collision coordinate system aims to achieve precise alignment between the floor model and the product model, while ensuring that the floor model's dimensions effectively cover the requirements of drop simulations. The floor model's thickness is determined by the set value in the drop direction (i.e., the collision coordinate system's Z-axis in the example above), while the floor model's length and width are determined by calculations along the collision coordinate system's X and Y axes. To further enhance the versatility and adaptability of the floor model, an algorithm is needed to automatically calculate and generate the floor model's dimensions in the collision coordinate system.

[0089] In order to determine the length of the floor model in the X-axis direction of the collision coordinate system, it is necessary to retrieve the coordinate values of all nodes of the product model in the X-axis direction of the global coordinate system and take out the maximum value respectively. X max and minimum value X min By calculating the difference between the two, we can get the maximum span of the model in the global X-axis direction:

[0090]

[0091] This span represents the extent of the model in the global X-axis direction.

[0092] The length of the floor model in the X-axis direction of the collision coordinate system is symmetrical with the collision coordinate point as the center. It extends to n times the maximum span of the global X-axis in both the positive and negative directions (n is an input value and can be adjusted):

[0093]

[0094] Thus, the total length of the floor model in the X-axis direction is , which can basically cover the falling range of the model and its potential impact range.

[0095] Similarly, the length of the floor model in the Y-axis direction of the collision coordinate system is calculated in the same way. First, the maximum value of all nodes in the Y-axis direction of the global coordinate system is retrieved. Y max and minimum value Y min , calculate the maximum span in the global Y-axis direction:

[0096]

[0097] Then generate the floor model length of the symmetrical structure in the Y-axis direction of the collision coordinate system:

[0098]

[0099] The total size of the floor model in the collision coordinate system is determined as:

[0100] Length in X-axis direction:

[0101] Y-axis length:

[0102] Z-axis thickness: fixed value or scene-based adjustment value.

[0103] The size expansion multiples of the floor model (such as n times in the X and Y axis directions) can be adjusted according to the actual application scenario to better meet the complex drop test requirements.

[0104] S2.4, build a rotating coordinate system, adjust the drop angle of the product model by rotating the coordinate system, and establish an association between the rotated floor model and the collision coordinate system to ensure that its contact surface accurately adapts to the collision conditions of the product. The specific process includes:

[0105] The input value of the rotation matrix is the rotation angle around the X, Y, and Z axes of the global coordinate system. 、 、 , the rotation matrix can be expressed as:

[0106]

[0107] Among them, the rotation matrices around the X, Y, and Z axes are:

[0108]

[0109] Where R is the rotation matrix, is the rotation matrix around the X axis, is the rotation matrix around the Y axis, is the rotation matrix around the Z axis.

[0110] By multiplying the above matrices, the initial plane of the floor model can be rotated to match the specified drop angle. This rotated floor model is then associated with the collision coordinate system, ensuring its contact surface precisely adapts to the product's collision conditions while maintaining the flexibility of dynamic adjustment. This approach effectively reduces the complexity of manual angle adjustment, improving operational efficiency and the accuracy of analysis results. By using reverse engineering, the drop direction can be altered by changing the floor model generation direction, achieving the same angle change.

[0111] S3, by measuring the time it takes for the reaction force of the floor model surface nodes to decrease to 0 or reach a set threshold, to calculate the effective duration. The effective duration refers to the time from the product contacting the floor model to the rebound. The set finite element analysis model is then obtained.

[0112] The calculation formula for the effective duration is:

[0113]

[0114] The floor model surface i Normal reaction force of each contact node at time t; N The total number of contact nodes representing the surface of the floor model; is the set reaction force threshold; The duration of the contact between the model and the floor model, that is, the time from the model contacting the ground to the completion of the rebound.

[0115] The specific steps include:

[0116] S3.1, extract reaction force data: monitor the reaction forces of all nodes on the floor model surface in real time and obtain the reaction force values of the nodes at each time step;

[0117] S3.2, determine the zero value state of the reaction force: set a threshold. When the reaction force values of all the surface nodes of the floor model are lower than the threshold, it is considered that the model has completed contact with the floor model.

[0118] S3.3, determine the end time of contact: When the reaction forces of all nodes are close to zero, calculate the end time of contact between the model and the floor model, marking the beginning of rebound.

[0119] S3.4, breakpoint command control: Based on the calculated contact end time, if the product rebounds from the ground during the solution process, a stop command is issued to stop the solution process and eliminate the remaining invalid calculation time.

[0120] S4, by inputting the product 3D model and drop height into the set finite element analysis model, simulates the product's drop process, and obtains the drop dynamic results and maximum stress cloud diagram. The specific process is as follows:

[0121] S4.1, obtaining relative displacement data based on the node displacement data of the product model recorded during the solution of the finite element analysis model, wherein the node displacement data describes the motion state of each node in units of time steps;

[0122] S4.2, by adding the relative displacement data to the original coordinates to calculate the absolute position of the node, and then reconstruct the instantaneous geometric state of the product model, that is, the geometric state at different time frames;

[0123] S4.3, connect the geometric states in different time frames in chronological order to form a complete dynamic sequence;

[0124] S4.4, adjust the time axis mapping to be consistent with the simulation time step;

[0125] S4.5, obtaining the drop dynamic results of the product model at a fixed viewing angle;

[0126] S4.6, traverse the stress values of the product model, obtain the time frame corresponding to the maximum stress value as the key frame, extract the stress distribution data corresponding to the key frame to generate a maximum stress cloud map, which intuitively presents the stress distribution status on the surface and inside of the model in the form of color gradient.

[0127] The generation of the drop animation is based on the node displacement data recorded during the solution process. This data is stored in the result file and describes the motion state of each node in time steps. In order to generate the animation, these displacement data need to be extracted, processed and reconstructed. Specifically, the extracted displacement data exists in the form of relative displacement, so the initial coordinates of the node need to be added back to calculate the absolute position to reconstruct the instantaneous geometric state of the model. This processing relies on numerical calculation methods to ensure the accuracy of the displacement data. In the animation generation stage, the geometric states of different time frames are connected in sequence to form a complete dynamic sequence. In order to synchronize the physical time and animation time, the mapping of the time axis needs to be consistent with the simulation time step. In order to improve the display effect, a fixed perspective can be used to display the model motion effect.

[0128] The purpose of generating a maximum stress contour map is to visualize the extreme stress conditions experienced by the model during the drop process by targeting key time frames. During the simulation, the result file for each time step records the distribution of equivalent stresses. By searching these time steps one by one, we can identify the time point at which the model was subjected to the greatest stress and its corresponding stress distribution. After targeting the key time frame, we extract the corresponding stress distribution data and generate a contour map. The contour map uses a color gradient to visually display the stress distribution on the model's surface and interior.

[0129] Example 2

[0130] A finite element drop analysis optimization device based on numerical calculation, comprising:

[0131] Drop conversion module, used to convert drop height into equivalent initial velocity;

[0132] a fall direction adjustment module connected to the conversion module, generating a collision coordinate system according to the fall direction based on the result of the fall conversion module and the contact situation between the product and the ground, and then generating a floor model based on the generated collision coordinate system;

[0133] A drop time identification module is connected to the drop direction adjustment module. Based on the results of the drop direction adjustment module, the module calculates the effective duration by measuring the time it takes for the reaction force of the nodes on the surface of the floor model to decrease to zero or reach a set threshold. The effective duration is the time from the product contacting the floor model to the rebound. The module then forms a pre-set finite element analysis model.

[0134] The drop solution module is connected to the drop time identification module and is used to simulate the product's drop process by inputting the product's three-dimensional model and drop height into the set finite element analysis model to obtain the drop dynamic results and maximum stress cloud map.

[0135] Example 3

[0136] A computer-readable medium includes a memory and one or more processors, wherein the memory stores executable code, and when the one or more processors execute the executable code, it is used to implement the finite element drop analysis optimization method based on numerical calculation described in Example 1.

[0137] Application Examples

[0138] The global coordinate system is the reference coordinate system during the model drawing phase and can be directly read in through the model file. The drop height is 1.3m and the product material is stainless steel.

[0139] like Figure 1 and Figure 2 As shown, the model diagram includes a collision coordinate system. The collision coordinate system is automatically generated. The collision point is the extreme point of the model in the falling direction. One axis is generated with reference to the axis in the falling direction, and the other two axes can be generated arbitrarily (here, the default is to reference the axes in the global coordinate system). The floor model display diagram is generated based on the collision coordinate system. The floor model in the falling direction is automatically generated by entering the floor model thickness and aspect ratio "n".

[0140] The origin of the rotating coordinate system is the geometric center of gravity of the model. The three axes refer to the axes of the global coordinate system. By inputting the rotation angles around the X, Y, and Z axes, the corresponding floor model is generated. Through reverse thinking, the direction of the floor model generation can be changed to change the direction of the fall.

[0141] Use the rotating coordinate system to adjust the model's drop angle. For example, rotating the coordinate system 45° counterclockwise around the X axis (X' axis in the figure) can be adjusted from Figure 3 The fall angle is converted into Figure 4 angle of fall. Figure 3 and Figure 4 The coordinate system in is a rotating coordinate system.

[0142] like Figure 5 The figure shows the stress cloud map corresponding to the key frame of maximum stress of the drop. The color of the legend on the left ranges from red to green to blue to gray, indicating the stress value from large to small. The unit is MPa.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field can still modify or replace the specific implementation methods of the present invention. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A finite element drop analysis optimization method based on numerical calculation, characterized in that: The steps include: S1, convert the falling height into equivalent initial velocity; S2, based on the results of S1 and the contact between the product and the ground, generates a collision coordinate system according to the falling direction, and then generates a floor model based on the generated collision coordinate system; The specific process includes: S2.1, by analyzing all nodes of the product's three-dimensional model in the global coordinate system, determine the extreme position point along the falling direction and set the extreme position point as the collision point; S2.2, set the collision point as the origin of the collision coordinate system, set the falling direction as a new axis of the collision coordinate system, use the determined new axis as the normal vector of the plane where the other two new axes are located, and then determine the directions of the other two new axes in the collision coordinate system; S2.3, calculating the size of the floor model in the collision coordinate system according to the collision coordinate system to form a floor model; S2.4, construct a rotating coordinate system, adjust the drop angle of the product model by rotating the coordinate system, and establish an association between the rotated floor model and the collision coordinate system. The specific process includes: The input value of the rotation matrix is the rotation angle around the X, Y, and Z axes of the global coordinate system. 、 、 ; The rotation matrix can be expressed as: Among them, the rotation matrices around the X, Y, and Z axes are: Where R is the rotation matrix, is the rotation matrix around the X axis, is the rotation matrix around the Y axis, is the rotation matrix around the Z axis; S3, by measuring the time it takes for the reaction force of the floor model surface nodes to decrease to 0 or reach a set threshold, to calculate the effective duration. The effective duration refers to the time from the product contacting the floor model to the rebound. The set finite element analysis model is then obtained. S4, by inputting the product 3D model and drop height into the set finite element analysis model, simulates the product's drop process and obtains the drop dynamic results and maximum stress cloud map.

2. The finite element drop analysis optimization method based on numerical calculation according to claim 1 is characterized in that: The specific process of step S2.3 is: S2.3.1, determine the thickness of the floor model based on the set value of the fall direction; S2.3.

2. Determine the length and width of the floor model using the calculation results for the X and Y axes of the collision coordinate system: Detect the coordinate values of all nodes of the product model in the X-axis direction of the global coordinate system, and determine the maximum span of the product model in the global X-axis direction by the difference between the maximum and minimum values. With the collision coordinate point as the center, extend the length of the floor model in the positive and negative directions of the X-axis of the collision coordinate system by integer multiples of the maximum span respectively. Detect the coordinate values of all nodes of the product model in the Y-axis direction of the global coordinate system, and determine the maximum span of the product model in the global Y-axis direction by the difference between the maximum and minimum values. With the collision coordinate point as the center, extend the length of the floor model in the positive and negative directions of the Y-axis of the collision coordinate system by integer multiples of the maximum span respectively.

3. The finite element drop analysis optimization method based on numerical calculation according to claim 1, characterized in that: The calculation formula for the effective duration in step S3 is: Where, The floor model surface i contact nodes at time t Normal reaction force at ; N The total number of contact nodes representing the surface of the floor model; is the set reaction force threshold; It is the duration of contact between the product model and the floor model, that is, the time from the product model contacting the floor model to the completion of rebound.

4. The finite element drop analysis optimization method based on numerical calculation according to claim 1, characterized in that: The method for calculating the effective duration includes the following steps: S3.1, extract reaction force data: monitor the reaction forces of all nodes on the floor model surface in real time and obtain the reaction force values of the nodes at each time step; S3.2, determine the zero value state of the reaction force: set a threshold value. When the reaction force values of all the surface nodes of the floor model are lower than the threshold value, the contact between the product model and the floor model is completed. S3.3, determine the end time of contact: when the reaction forces at all nodes are close to zero, calculate the end time of contact between the model and the floor model, marking the beginning of rebound; S3.4, breakpoint command control: Based on the calculated contact end time, if the product rebounds from the ground during the solution process, a stop command is issued to stop the solution process and eliminate the remaining invalid calculation time.

5. The finite element drop analysis optimization method based on numerical calculation according to claim 1, characterized in that: The specific process of step S4 is: S4.1, obtaining relative displacement data based on the node displacement data of the product model recorded during the solution of the finite element analysis model, wherein the node displacement data describes the motion state of each node in units of time steps; S4.2, by adding the relative displacement data to the original coordinates to calculate the absolute position of the node, and then reconstruct the instantaneous geometric state of the product model, that is, the geometric state at different time frames; S4.3, connect the geometric states in different time frames in chronological order to form a complete dynamic sequence; S4.4, adjust the time axis mapping to be consistent with the simulation time step; S4.5, obtaining the drop dynamic results of the product model at a fixed viewing angle; S4.6, traverse the stress values of the product model, obtain the time frame corresponding to the maximum stress value as the key frame, extract the stress distribution data corresponding to the key frame to generate the maximum stress cloud map.

6. A finite element drop analysis optimization device based on numerical calculation, characterized in that: include: Drop conversion module, used to convert drop height into equivalent initial velocity; The fall direction adjustment module is connected to the conversion module and generates a collision coordinate system according to the fall direction based on the results of the fall conversion module and the contact between the product and the ground, and then generates a floor model based on the generated collision coordinate system. Specifically, it includes: By analyzing all nodes of the product's three-dimensional model in the global coordinate system, the extreme position point along the falling direction is determined and set as the collision point; Set the collision point as the origin of the collision coordinate system, set the falling direction as a new axis of the collision coordinate system, and use the determined new axis as the normal vector of the surface where the other two new axes are located, thereby determining the directions of the other two new axes in the collision coordinate system. Calculate the size of the floor model in the collision coordinate system according to the collision coordinate system to form a floor model; Construct a rotating coordinate system, adjust the drop angle of the product model by rotating the coordinate system, and associate the rotated floor model with the collision coordinate system. The specific process includes: The input value of the rotation matrix is the rotation angle around the X, Y, and Z axes of the global coordinate system. 、 、 ; The rotation matrix can be expressed as: Among them, the rotation matrices around the X, Y, and Z axes are: Where R is the rotation matrix, is the rotation matrix around the X axis, is the rotation matrix around the Y axis, is the rotation matrix around the Z axis; A drop time identification module is connected to the drop direction adjustment module. Based on the results of the drop direction adjustment module, the module calculates the effective duration by measuring the time it takes for the reaction force of the nodes on the surface of the floor model to decrease to zero or reach a set threshold. The effective duration is the time from the product contacting the floor model to the rebound. The module then forms a pre-set finite element analysis model. The drop solution module is connected to the drop time identification module and is used to simulate the product's drop process by inputting the product's three-dimensional model and drop height into the set finite element analysis model to obtain the drop dynamic results and maximum stress cloud map.

7. A computer-readable medium comprising a memory and one or more processors, wherein the memory stores executable code, and when the one or more processors execute the executable code, the one or more processors are used to implement the finite element drop analysis optimization method based on numerical calculation according to any one of claims 1 to 5.

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