Two-Stage Bending Test for Automotive Metal Sheet Collision Evaluation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing material test methods for evaluating the collision performance of high-strength metal sheet materials used in automobile bodies are inadequate as they fail to accurately reproduce complex deformation phenomena and exhibit high variation in results.
Innovation Solution
A collision performance evaluation test method and facility that involves forming a flat test specimen into a V shape by primary bending and then subjecting it to secondary bending in a direction intersecting with the primary bending direction, while recording and evaluating the bending load and stroke during the secondary deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-strength metal sheet materials are used to reduce automobile body weight, then collision performance and weight reduction are improved, but ductility decreases and the risk of fracture or crack development increases
Solution Approach 1:
The patent applies preliminary action by performing press working (forming) on the test specimen before conducting the bending test. This pre-deformation step simulates the actual manufacturing process and creates initial strain patterns that will concentrate during subsequent bending, allowing the test to predict fracture risk more accurately. The preliminary forming step prepares the material in a state that reflects its actual service condition before collision occurs.
2Loss of energy
If axial compression deformation is used to absorb collision energy, then collision energy absorption efficiency is improved, but local plastic strain exceeds ductility limit and causes catastrophic fracture
Solution Approach 1:
The patent performs preliminary press working to form the test specimen into a complex shape with specific geometric features (such as V-shaped sections) before bending testing. This pre-forming creates predetermined strain concentration zones that will develop during axial compression or bending, allowing the test to identify materials that can absorb energy without catastrophic fracture. The preliminary action prepares the material structure to reflect actual collision conditions.
Solution Approach 2:
The patent changes the test parameters by evaluating not just the final bending result but also the behavior during the bending process. By measuring load-stroke curves and analyzing deformation patterns at different stages, the test identifies materials that can undergo large plastic deformations (exceeding traditional elongation limits) without fracturing, thus capturing energy absorption capability while maintaining fracture resistance.
3Device complexity
If conventional bending test methods are used to evaluate material properties, then test simplicity is improved, but actual complex deformation phenomena during collision cannot be sufficiently reproduced
Solution Approach 1:
The patent introduces a preliminary press working step before the bending test, transforming a simple bending test into a two-stage process. This preliminary action forms the test specimen into a shape that reflects actual automobile body parts, creating initial strain patterns that will concentrate during subsequent bending. This maintains relative test simplicity while dramatically improving the reproduction of actual collision deformation phenomena.
Solution Approach 2:
The patent changes the evaluation parameters by analyzing the load-stroke curve during bending and identifying specific characteristics (such as abnormal load drops or deformation patterns) that indicate fracture risk. This goes beyond simple pass/fail bending tests to provide detailed information about material behavior under complex deformation, improving measurement precision while building upon conventional test methods.
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 allows for the precise evaluation of collision performance with reduced variations, effectively reproducing the complex deformation phenomena that occur during actual collisions by considering the histories of deformation in both press forming and collision.
Implementation Method 1
a press working apparatus forms a flat test specimen made of a metal sheet material to be tested into a V shape by primary bending
Implementation Method 2
a bending test apparatus deforms the test specimen that has been formed by the primary bending in a direction intersecting with a primary bending direction, by secondary bending
Data Source
AI summary
A collision performance evaluation test with few variations in test results with high accuracy in which a complicated phenomenon that actually occurs can be reproduced in a simple manner by considering the history of deformation in both the press forming and a collision. A collision performance evaluation test method for a metal sheet material for an automobile body is characterized in that a press working apparatus first forms a flat test specimen made of a metal sheet material to be tested into a V shape by primary bending, a bending test apparatus then deforms, by secondary bending, the test specimen formed by the primary bending in a direction intersecting with the primary bending direction, and a bending load and a bending stroke for the test specimen during the secondary bending deformation are recorded and evaluated.