Friction Grip Load Balancing for Composite Coupon Testing
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Solution Overview
Problem
The current material load testing processes are time-intensive and costly, especially when testing new composite materials, due to the need for fabricating and testing multiple coupon configurations, which is exacerbated by the complexity of composite structures.
Innovation Solution
An apparatus and method for load testing a coupon using a test frame with load balancing assemblies that securely grip the coupon through friction and distribute even loads, allowing for efficient application of tensile or compressive loads, reducing the need for complex coupon fabrication and attachment features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coupons are fabricated with tabs and holes for attachment to test jig, then the coupon can be securely attached and tested, but the fabrication process becomes time-intensive and costly
Solution Approach 1:
The invention extracts the attachment features (tabs and holes) from the coupon itself and relocates them to the test jig. The coupon becomes a simple flat sample without any pre-fabricated attachment features, while the test jig incorporates clamping devices with jaws that directly grip the coupon edges. This eliminates the time-consuming fabrication of tabs and holes in the coupon while maintaining secure attachment during testing.
Solution Approach 2:
Instead of attaching the coupon to the test jig through features on the coupon (tabs and holes), the invention inverts the approach by having the test jig's clamping devices directly grip the coupon. The attachment mechanism is reversed from coupon-centric to jig-centric, eliminating the need for coupon modification while achieving secure attachment.
2Loss of information
If multiple coupon configurations are tested for new composite materials, then comprehensive material strength information is obtained, but the testing process becomes prohibitively time-intensive and costly
Solution Approach 1:
The invention creates a universal testing apparatus that can test multiple coupon configurations and orientations using the same clamping mechanism. The load balancing assembly with multiple load plates can accommodate different coupon sizes, shapes, and orientations without requiring specialized fixtures for each configuration, enabling comprehensive material evaluation through a single multi-functional system.
Solution Approach 2:
The load balancing assembly incorporates movable components including load plates that can pivot and adjust to accommodate different coupon configurations. The system dynamically adapts to various testing scenarios through movable clamping jaws and adjustable positioning, allowing rapid reconfiguration between different material tests without time-consuming fixture changes.
3Force
If load is applied to coupon through tabs and holes, then the load can be transmitted to the test jig, but stress distribution across the coupon becomes uneven
Solution Approach 1:
The load balancing assembly divides the load transmission into multiple segments through several load plates distributed across the coupon width. Each load plate independently transmits load to the coupon at different locations, and the segmentation allows for even load distribution across the entire coupon surface, eliminating stress concentrations that would occur with single-point attachment through tabs and holes.
Solution Approach 2:
The invention applies load through multiple load plates that contact the coupon at multiple points simultaneously, providing excessive load application points beyond what a single tab connection would provide. This partial distribution of load across multiple contact points ensures uniform stress distribution and prevents localized stress concentrations.
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 significantly reduces the time and cost associated with material testing by simplifying the testing process and allowing for faster evaluation of material strength properties under various load conditions, particularly for composite materials.
Implementation Method 1
a friction holder configured to frictionally engage an end of the coupon
Implementation Method 2
a load balancing assembly configured to retain an end of the coupon and communicate an axial load to the coupon upon movement along an axis
Data Source
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AI summary
An apparatus (10) for load testing a coupon (11) may include a test frame (12) and a pair of spaced apart load balancing assemblies (16a, 16b) connected to the test frame (12), each load balancing assembly (16) of the pair of load balancing assemblies (16a, 16b) including a load leveling mechanism (160) connected to the test frame (12) and a plurality of spaced apart load plates (54), each load plate (54) of the plurality of load plates (54) having a first end (112) pivotably connected to the load leveling mechanism (160) and a second end (118), the second end (118) of each load plat (54)e including a friction holder (104) configured to frictionally engage an end of the coupon (11), wherein at least one load balancing assembly (16) of the pair of load balancing assemblies (16a, 16b) is movable along an axis (X) of movement with respect to an opposed load balancing assembly (16) to communicate a load to the coupon (11).