Automobile collision real and false people research significance detailed

Modern collision simulation software package consists of the pre-processing / post handler module and the numerical calculation module. The industrial use efficiency of the collision simulation software package depends not only on the computational programming efficiency, but also to a large extent, the quality, efficiency, and its user and coherence of the preceding / post-processing program module connected thereto. The PamGeneris preprocessing program module and PAM-View postparted program modules are currently available. Currently, both program modules are undergoing large-scale improvement and reconstruction to sufficiently guarantee the applicability and success of their industrial use. The PAM-Solid computing program includes PAM-CRASH car collision analysis programs, PAM-SAFE passenger safety analysis programs, PAM-STAM thin plate stamping procedures, and PAM-SHOCK shocks and high-speed response analysis programs. This article focuses on the PAM-Crash car collision analysis program. Next, the Qinsun will summarize from five aspects.

First, the new progress of the algorithm

Although the industrial efficiency and stability of modern explicit finite element collision simulation calculation procedures have reached considerable levels, there is still a great place for the improvement and development of algorithms. . The work that will now be described in this regard.

1.1 Contact Simulation

It should be noted that in the collision simulation, the correct and complete object indirect touch simulation is a prerequisite for its success.

, it is worth noting that whether it is using a single processor (or shared storage parallel) program, or use large-scale distributed storage parallel programs, the contact simulation is always challenging and most complicated. Program design tasks. In the first case, in order to make the calculated ldquo; rigid wall rdquo; limiting or ldquo; sliding contact surface rdquo; processing must be as reasonable as possible. For the contact algorithm of the sliding contact surface, it has been proven to have a wide range of punishment compensation methods. Current development trends are efforts to make this approach as much as possible to understand the end users, including the need to overcome difficulties encountered in computational efficiency and accuracy. Comparison of airbag contact treatment in the application of the original and improved penalty compensation contact algorithm.

For the preparation of large-scale parallel programs, the explicit finite element program can be easily enabled by using effective automatic regional division technology. Each parallel processor only needs to perform a small amount of communication with other processes to complete a large number of similar models. Since the determined contact area is not static (when the structure is deformed, the original area is connected to each other), the original area is quickly not applicable. If the original contact calculation is represented, the information is transmitted. The amount of large increments and extremely imbalanced workload are allocated. Therefore, the collision simulation program is large in parallelThe important work in the interface is the effective parallelity of the contact algorithm.

1.2 Grid Debar Algorithm

In the collision simulation of thin plate components and structures, the main objective of grid autism algorithm technology is the thin shell finite element network near the large deformation zone. Automatic partial refinement. This issue has been resolved in the stamping simulation of industrial metal sheets. The PAM-Stamp thin plate stamping simulation procedure adopts a program that can be uniform and automatically selecting thin shell mesh refinement and roughening.

The first cause of mesh variable algorithm is difficult to apply to collision simulation, and it is necessary to make the adaptability of the grid and the choice of large-scale contact processing and rigid wall contact / impact. While contact is the dominant mechanism of thin plate stamping, since the tool geometry used and the self-contained self-containement of the sheet is substantially non-existing, it is relatively simple. In collision simulation, self-contained contacts often appear, and it is more difficult to correct them to apply grid autism algorithm.

The two reasons for collision simulation and even dangerous collision simulations are limited to the plastic corners or in collision zones. That is, in the actual calculation of the refined grid region its rigidity is smaller than the original thicker grid, and the plastic corners of unfinened grids may be added soft or decreased. The desascation area of the calculation resistance is calculated. Therefore, in order to avoid this limitation, the refinement standard must be seriously selected, and the original grid cannot be too thick.

Application examples of grid autism algorithm include the axial impact of thin-walled tank columns (Fig. 2A), a large-deformable plastic corner region in the S-shaped frame (Fig. 2b), the front of the passenger car collision (Fig. 2C) and the metal sheet stamping.

Design, calibration and confirm that various material models are more and more attention to the description of aluminum alloys, plastics, foam materials, rubber and composites. Pam Mdash; Solid program includes models for describing these material behavior.

Second, the following is highly introduced.

2.1 Elastoplastic / strain rate / injury model

The finite element method in the Pam-Solid program uses a variety of partnerships and anisotropic elastoplastic materials and damage to the strain rate. Material model. Material stress mdash; strain ordinary law, as shown in Figure 3. Figure 3A is a reactive and injury curve. In principle, the method can be applied to various materials. Basic unscrupulous stress mdash; strain law. Number reduces material strength. The general description of the damage here is attributed to Lemaitre-ChBoche, which is applied to any material, such as metals, plastics, composites, and foam materials. Currently, we work with Valenciennes University to use Gurson damage mode for tough metal to describe plastic strain andThe nucleus of material micro-gaps, growth and coalescence on material behavior. In different scale models, the effect of void or damage to stress is shown in Figure 3B.

2.2 Aluminum alloy

The plastic behavior of aluminum alloy can be described in Figure 4 using a non-quadratic yield function that can be used for anisotropic material. This model has been used in the PAM-Stamp program and has been used for the aluminum plate deep rail.

2.3 Plastic

In the simulation of plastic, the general plastic exhibits first-softened elastoplastic behavior. First, the finite element model is used to simulate the stress mdash; the softening phase on the strain curve (Fig. 5A), once plastic stress sigma; reduces to the precipitation modulus Et, plastic instability (neck) is produced. When a plastic strain reaches a certain rupture limit, this instability quickly leads to a concentrated and test piece of the plastic strain. Next, modifications to the original plastic hardening curve (Fig. 5B) to strengthen the formation of higher plastic strain, thereby limiting the planar stress conditions sigma; et; Epsilon; 1 lt; epsilon; lt; epsilon; 2 In the range. The initial neck is still developed as before, but now the finite element of the necklace area is stretched to plastic strain epsilon; 2 or more, the hardening of the material inhibits the neck. Thus, the neckline expands the finite element around it and gradually invades the entire test piece.

2.4 Other Materials

For the description of the lateral obstacles, pads, and mechanical prosthetic foams, PAM-SO

LID software has a variety of models available to simulation The rupture of the material, compression, viscosity deformation, and behavior associated with the rate.

For rubber materials and similar to rubber materials, such as tires, engine brackets, and dummy components, there are also many superplasticity and quasi-non-compressed materials.

For the collision simulation of fiber reinforced materials, models of susceptible damage materials have been used. These models have also been extended to other composites.

Of course, all of these material models need further improvements. The new material model will continue to appear to meet the growing needs of the industrial sectors to improve their specific products.

Third, the concept collision design

A fun trend in collision simulation is that the industrial community is increasingly requires simple collision simulation means, especially the early stages of the design of the transportation equipment. At present, the existing collision simulation practice emphasizes the final stage, that is, the most limited emitted overall model (limited element 20,000 to 100,000, even more), the most designed structureCalibration of final collision performance. However, when the collision performance of the design structure may not make the information and time required for a detailed collision verification model. Therefore, simplified methods are more popular.

One of the examples of concept collision design is a box column. Currently, the ESI Group is studying the image user interface required for this concept collision based on the power ultrastay software (PAM-Superfold) developed by the University of Valenciennes. In this interface, the user can enter the wall thickness and material characteristics of the box column. By power ultrastay software, the impact reactions under the circumference of the axial or deep bending in the unstable conditions are calculated. It is also possible to use another PAM-OPT program currently developed, and achieve the best response required by automatically changing a set of input optimized parameters and limiting variables. Then, the components of the determined thickness can be subjected to automatic finite element mesh, and the calculation verification is performed in the PAM-CRASH finite element software. Since the subsequent collision design process can put the collision component reaction curve into the collision program to specifically design three-dimensional beam / nonlinear elastic or integral beam unit model. Then thereafter form a transition from an early collision design to a structural node, which has a practical geometry, a cutoff point, and a connection. In this hybrid phase, the grid of the critical area can be refinered, while other parts of the structure can only be roughly simulated. In the final stage, the most fine model confirmed the overall design.

Four, security

In addition to the development of deformable impact obstacles (side hits and collision) models and various mechanical dummy models (composite III, European side hit type, United States In addition to the lateral type, bio-side hit and child, the human biomechanical model has also been developed. This work will be greater, because the simulation of the biological model of the human body is the only way to get a direct reaction of the collision event. The ESI Group has developed this type of model (such as head and lower leg). Leg initial models include bone, ligament, tendon and muscle model.

V.

The collision simulation technology and procedures can not only be successfully used for automotive collision simulation, but also in many other relevant areas. For example, a buffer packaging material designed for the refrigerator, the drop test of home appliances (such as small computers) to estimate the damage of sensitive components and collision simulation of hard landed for space detection. In addition, the tires react to the reaction when rolling the projections, and the impact reactions such as bridges, cranes, rails, containers, trains, vessels, trucks, tractors, and bicycles can be used. . In fact, the scope of application of collisions and impact simulation software is constantly growing.

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