NASA ACC High Energy Dynamic Impact Methodology and Outcomes

Abstract

For High Energy Dynamic Impact (HEDI) events, testing to evaluate the structural response of primary aircraft structure for design and certification is both expensive and time consuming. This paper discusses current work seeking to assess, develop, and validate appropriate analytical models that accurately predict physical response, damage, and failure modes for large scale composite structures in HEDI events. Four state-of-the-art Progressive Damage Analysis (PDA) methods were employed for this phased project: LS-DYNA MAT162, LS-DYNA MAT261, Smoothed Particle Galerkin (SPG), and EMU Peridynamics. Multiple material systems were considered, namely T700/5208 textile-infusion triaxial braid, T800/AMD-825 textile-infusion triaxial braid, IM7/8552 uni-directional tape, and SPG 196-PW/8552 plain-weave fabric. Extensive ballistic impact testing was performed to support this activity and measured results were compared to predictive models for assessment using panel delamination, panel displacement, force at the load cells, and threshold velocity as measures. Ultimately, the work under this activity provided significant progress in advancing the state-of-the-art in the use of PDA for HEDI events. Each material model had favorable performance comparing to test in some parameters and needed improvement in others. With the lessons learned from this activity, significant progress was made in the ability to predict panel behavior for a more general case beyond the flat panel in a ballistic impact event. Subsequent Phase II of the NASA ACC HEDI effort will continue to build on the coupon testing, flat panel ballistic impact testing, and analysis performed to-date with application of the PDA methods for intended material selections to test articles with greater complexity of configuration, curvature, and scale. It is not the intention of this paper to present a full set of data, but rather to give an overview of the NASA HEDI effort and show a small representative subset of the test and analysis results.

Quantification of Error Associated with Using Misaligned Meshes in Continuum Damage Mechanics Material Models for Matrix Crack Growth Predictions in Composites 2385

“…The Composite Airframe Life Extension (CALE) program from the Wright Patterson Air Force Research Laboratory has examined the use of these tools on bolted structures [1], [2]. Further, the NASA Advanced Composites Project (ACP) has chartered the goal of improving methods for targeted applications of fatigue, post-buckled stiffened panels with barely visible impact damage [3], and high energy dynamic impact [4].…”

Comparison of Test Methods to Determine Failure Parameters for MAT162 Calibration

“…Further, the HEDI Team seeks to develop novel PDFA methods and to create industry standards for best practices for evaluating and using these methods for a variety of high energy impact events. An overview of the NASA ACC HEDI effort including the use of LS-DYNA MAT162, LS-DYNA MAT261, Smoothed Particle Galerkin (SPG), and EMU Peridynamics to HEDI was presented [5] with detailed methods and results for LS-DYNA MAT261 [6] and EMU Peridynamics [7]. The focus of this paper is the comparison of material test methods used to obtain failure properties unique to LS-DYNA MAT162.…”