Crush Failure Modeling in Composite Structures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing finite element analysis techniques fail to accurately model the crush failure mode of composite materials, leading to inaccurate results and unrealistic failures in vehicle body parts under impact, as they do not account for the gradual disintegration and debris-induced forces that affect the structure's integrity.
Innovation Solution
A method and apparatus for calculating the impact resistance of structures with crushable materials by determining the ongoing resistance force and a further force that separates bonded parts due to debris creation, which is not fully compressible, allowing for more accurate modeling of crush failure modes in composite materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing finite element analysis techniques are used to model crush failure mode, then the analysis is simpler and faster, but the results are inaccurate and do not reflect actual material behavior
Solution Approach 1:
The element is divided into two distinct zones: an intact zone that maintains structural integrity and a crushed zone that models the disintegrated material. This segmentation allows the model to capture the gradual transition from intact to crushed state, accurately representing the crush failure mode while maintaining computational feasibility through zone-based differentiation.
Solution Approach 2:
The model employs parameter changes by transitioning elements from an intact state with full structural properties to a crushed state with degraded properties. The crushed zone parameters are adjusted to reflect the disintegrated material behavior, including reduced stiffness and strength, while the intact zone retains original properties. This parameter evolution accurately models the progressive crush failure.
2Reliability
If classical failure stress deletion is used, then the element is removed from analysis after failure, but this creates unrealistic forces and unexpected failures in backup structure
Solution Approach 1:
The crushed zone acts as an intermediary between the intact element and the backup structure. Instead of abruptly deleting the element, the crushed zone provides a gradual transition with degraded but non-zero stiffness, allowing forces to be transmitted in a more realistic manner. This intermediary zone prevents the generation of unrealistic peak forces that would otherwise be propagated to the backup structure.
Solution Approach 2:
The model prepares for force mitigation by creating the crushed zone before complete element failure. This crushed zone serves as a cushion that absorbs and distributes impact forces gradually, preventing sudden force spikes. The prior creation of this transitional zone cushions the backup structure from unrealistic force loads, improving the reliability of the overall model.
3Measurement precision
If the element is treated as maintaining integrity until failure stress, then the analysis is simpler, but it does not reflect the gradual disintegration and debris creation in crush failure
Solution Approach 1:
The element is segmented into intact and crushed zones, where the crushed zone represents the disintegrated material. This segmentation captures the gradual disintegration process by allowing the crushed zone to grow progressively during impact, reflecting the transformation from consolidated material to debris while maintaining computational tractability through zone-based modeling.
Solution Approach 2:
The model introduces dynamics by allowing the crushed zone to evolve over time during the impact process. The proportion of crushed versus intact material changes dynamically as the impact progresses, capturing the progressive disintegration. This dynamic approach reflects the real-time transformation of material state without requiring overly complex progressive deletion schemes.
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 approach provides a more accurate simulation of the impact resistance and structural behavior under crush failure, preventing premature failures and ensuring adequate energy absorption in vehicle body parts by accounting for the forces generated by debris, thus enhancing the design of composite vehicle body parts.
Implementation Method 1
On the microscopic scale such materials absorb energy by local disintegration of the material, by matrix cracking, fibre buckling and fracture, frictional heating etc.
Data Source
AI summary
A method of calculating an impact resistance of a structure undergoing an impact with an impact surface is disclosed. The structure includes a first part bonded or secured to a second part, at least the first part comprising a material having a crush failure mode. The method comprises:a) determining that a finite element representing a portion of the first part is experiencing conditions which dictate that it will undergo the crush failure mode;b) determining a behaviour of the structure assuming it is subject to:i) an ongoing resistance force representing the crush failure mode of the element; andii) a further force F acting on the first and second parts in a direction tending to separate them.