Tubular Composite Specimen Wrinkle Testing
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Solution Overview
Problem
Current methods for testing composite components with defects, such as wrinkles, in rotorcraft are costly, time-consuming, and produce inconsistent results due to uncontrollable defect size and shape, making it difficult to determine allowable defects and manufacturing defects are challenging to eliminate, leading to increased scrap rates and prolonged development times.
Innovation Solution
A method for creating tubular specimens with predetermined wrinkle defects by using a layup tool with a cavity to form a closed loop of composite material, where a wrinkle tool is used to generate specific wrinkle characteristics, and the specimen is then cured and tested using an offset load testing apparatus to simulate real-world defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full scale parts with defects are tested, then realistic defect representation is achieved, but cost and time consumption increase significantly
Solution Approach 1:
The patent creates simplified tubular specimens that copy only the essential features of real composite structures (layered construction, curvature) while eliminating unnecessary complexity (full scale dimensions, complex geometry). This allows testing of wrinkle defects in a controlled, time-efficient manner that still provides representative data for certification decisions.
Solution Approach 2:
The patent extracts the critical testing element (wrinkle defect) from the complex full-scale component and isolates it in a simplified tubular specimen. By removing non-essential features and focusing only on the defect characteristics and their impact on structural integrity, the testing process becomes much faster while maintaining measurement precision for defect assessment.
2Loss of time
If subscale parts with inclusions are used, then testing time is reduced, but defect representation becomes less accurate
Solution Approach 1:
The patent applies local quality by creating tubular specimens with specific local features (curved geometry, layered construction) that match the local conditions where wrinkles occur in real components. The specimens are subscale but maintain the critical local characteristics needed for accurate defect representation, achieving both time efficiency and measurement precision.
3Adaptability or versatility
If manual wrinkle creation methods are used, then manufacturing flexibility is maintained, but manufacturing precision and consistency deteriorate
Solution Approach 1:
The patent uses preliminary action by pre-forming the wrinkle defect in the tubular specimen before curing the composite material. The wrinkle tool is positioned and the wrinkle is created while the material is still in its formable state, allowing precise control of wrinkle characteristics. This preliminary formation ensures consistent, repeatable defects across multiple specimens while maintaining the flexibility to create different wrinkle types.
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 allows for controlled creation and testing of composite specimens with consistent defects, enabling the determination of allowable defect profiles and improving manufacturing efficiency by standardizing the testing process and reducing production costs.
Implementation Method 1
orienting a composite material around the mandrel at a wrap angle to form a closed loop
Implementation Method 2
generating at least one wrinkle with a predetermined characteristic in a portion of the closed loop
Implementation Method 3
providing a layup tool with a cavity forming member having a cavity which resembles a desired shape of the at least one wrinkle
Data Source
AI summary
A method of offset load testing a tubular composite specimen with two pairs of aligned holes and having at least one defect, the method comprising: providing a testing apparatus having a pair of arms including a fixed arm and a mobile arm; securing the pair of arms using a fastener assembly in each of the two pairs of aligned holes; and moving the mobile arm to impart an offset load force to the tubular specimen. One aspect includes a method of offset load testing comprising: providing a testing apparatus having a pair of arms including a fixed arm and a mobile arm; providing a tubular composite specimen with a top portion and a bottom portion; securing the pair of arms to the top and bottom portions of the tubular composite specimen; and moving the mobile arm to impart an offset load force to the tubular composite specimen.