Grid Model Collision Simulation for Acceleration Curves

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Solution Overview

Problem

Current collision simulation methods are either too inaccurate or too time-consuming, failing to provide a fast and detailed estimation of acceleration curves during collisions, which is crucial for assessing the severity of accidents and evaluating driver assistance systems.

Innovation Solution

A method using a grid model with direction-dependent and location-dependent energy values to simulate collisions iteratively, calculating deformation and impact force, and determining acceleration, allowing for a detailed and realistic simulation of collisions in a short time frame.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the finite element method (FEM) is used to calculate collisions, then detailed and highly accurate results such as deformations and accelerations can be obtained, but the calculation time increases to hours or days

Engineering Contradiction:
Improveaccuracy of deformation and acceleration calculationVSAvoidcalculation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the collision calculation process into distinct phases: elastic compression, plastic compression, and elastic restitution. Each phase is handled with appropriate simplifications - elastic phases use spring-based models while plastic compression uses energy-based models. This segmentation allows accurate deformation and acceleration calculation without requiring full FEM throughout the entire collision process, thus reducing calculation time while maintaining accuracy where needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes parameters dynamically based on the collision phase. The shock drive parameter is used to transition between elastic and plastic compression phases. During elastic phases, stiffness parameters are used; during plastic compression, energy absorption parameters take over. This parameter switching enables accurate acceleration calculation during critical phases while using simplified models during less critical phases, resolving the accuracy-time contradiction.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If simplified collision models are used to reduce calculation time, then fast results can be obtained, but the accuracy of deformation and acceleration calculations decreases

Engineering Contradiction:
Improvecalculation speedVSAvoidaccuracy of acceleration curve
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies different levels of model complexity to different parts of the collision process. Local quality is maintained by using detailed energy-based plastic compression models only when and where plastic deformation occurs, while using simpler elastic spring models for elastic phases. This localized application of complexity ensures accurate acceleration curves are generated during critical plastic deformation phases without requiring computationally expensive models throughout the entire simulation, thus achieving both speed and accuracy.

Inventive Principle:
Principle #3Local quality

3Device complexity

If vehicle stiffnesses are reduced in force calculation methods to simplify the model, then calculation speed increases, but the accuracy of results decreases

Engineering Contradiction:
Improvemodel complexityVSAvoidaccuracy of collision results
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent makes the model dynamic by transitioning between different stiffness representations based on the collision phase. During elastic compression, full vehicle stiffness is used to accurately capture elastic behavior. During plastic compression, the model switches to energy-based plastic deformation models that inherently account for material nonlinearity without requiring reduced stiffness parameters. This dynamic adaptation allows accurate results without permanently simplifying the model structure, resolving the contradiction between model complexity and accuracy.

Inventive Principle:
Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method enables fast, detailed, and versatile collision simulations that accurately calculate acceleration curves, addressing the limitations of existing methods by providing a balanced approach between accuracy and computational efficiency.

Implementation Method 1

the grid point with the lower energy value is viewed as deformed and its status is changed

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

the grid point with the higher energy value is reduced in its energy value by the amount of the energy value of the grid point with the lower energy value

Methodology Applied
Scientific EffectEnergy transfer: Mechanical Force

Data Source

PatentEP4009216A1Method for modelling a collision of two vehicles
Publication Date: 2022.06.08 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP4009216A1 patent drawingFigure 1~2
  • EP4009216A1 patent drawingFigure 3
  • EP4009216A1 patent drawingFigure 4

AI summary

The present invention relates to a method for modeling a collision of two objects, in which a one-dimensional to three-dimensional grid model, having several grid points, is generated for each of the two deformable objects.The collision is then simulated by iteratively calculating plastic compression upon the impact of the two objects with the grid models. This is done by simulating the acting forces using predefined mechanical equations. First, the two objects collide at an initial velocity, and the grid points of each object affected by deformation are determined. Subsequently, a direction, point of application, and magnitude of an impact force are derived for each grid point from these deformation points. Based on the calculation of the impact force for the sum of all grid points, a resulting acceleration is determined for each of the colliding objects. Finally, a velocity and position of each object are calculated from the acceleration.Each of the grid points has a direction-dependent and location-dependent energy value or an energy-equivalent value to map stiff and soft areas of the respective object, and the energy value or energy-equivalent value of each of the deformed grid points is added to the plastic deformation energy of the respective iteration.