Novel Analytical and Experimental Methods for Evaluating Repairs in Composite Honeycomb Structure

ABSTRACT: The overarching objective for this project is to develop a validated analysis tool to predict the behavior of damaged and repaired honeycomb sandwich structures. The primary objective for the proposed Phase II effort will be to develop a prototype design environment for a fully parametric, calibrated and validated, honeycomb sandwich structure damage and repair evaluation design environment using multiple capabilities of StressCheck and a Design OF Experiments approach to calibration, validation, and verification of the analytical models. This analytical tool will demonstrate the feasibility of a multi-scale, FEA-based, design and analysis tool capable of evaluating the various details of typical honeycomb sandwich structure at a scale that is adequate for each detail of interest. A test program, based upon the widely adopted and accepted building block format, will be used to perform two main functions. The first function will be to supply relevant and unique coupon and element level test data that will be used to calibrate the FEA-based analysis models. The second function will be to generate higher level (element and sub-component) test data to validate the analysis tools over the entire realm of the design space over which the tool is expected to be deployed. BENEFIT: Following the success of the Phase II prototype development effort, the design environment developed in Phase II can be made available for initial deployment for evaluation and improvement. Involvement of initial users can be leveraged to accelerate the development and expansion of the capabilities of the tool in parallel with the Phase III effort. When brought to fruition in Phase II, the end result will be a calibrated and validated analytical design environment prototype that can be widely deployed among the dispersed engineering teams on any given program. It will be capable of addressing in a parametric fashion, multiple types of damage and failure, along with subsequent repairs. This initial set of configurations will allow engineering teams to investigate a wide range of damage and repair scenarios. The design environment developed in Phase II will be structured as a modular, multi-scale, and expandable tool. Customers will be able to integrate this tool within their existing analytical framework in a complementary manner. It will incorporate a fully parametric formulation for every aspect of the inputs and outputs of the 3D solid element, ply-by-ply FEA models that will allow for encapsulation and automation of the entire set of analytical steps required to fully evaluate any given range of configurations. This will also allow the user to capture every relevant detail that may have an effect on the evaluation. The Phase II test effort will provide a good foundation for determining a standardized methodology for calibrating and validating analytical models such that they can be trusted to yield accurate results over the entire segment of the design space that they are configured to evaluate. This approach will open up the entire feasible design space for use by the engineer.