MSC Software | CASE STUDY Case Study: German Aerospace Center (DLR) Unfolding of Composite L-Angles; Analytical and Numerical Calculation Compared to Test Results Overview The goal of the German Aerospace Center (DLR) was to find the most optimized layup for composite laminate L-angles to maximize their strength and decrease early failure in the composite. Utilizing a standard unfolding test method for an L-Angle, DLR did comparisons against theoretical (hand-calculated), test, and finite element methods. The results completed by finite element analysis using MSC Nastran Implicit Nonlinear (SOL400) proved to offer a very good consistency between numerical calculations and test. MSC Nastran implicit Nonlinear (SOL400) proved to be within 1 standard deviation of almost all tests performed, proving MSC Nastran as an accurate tool for enabling engineers to perform composite analysis. Challenge beam consists of two straight legs connected by a 90 bend with a 6.4-mm [0.25 in.] DLR is the National Aeronautics and Space Key Highlights: inner radius. An out-of-plane (through-the- Research Center of the Federal Republic of thickness) tensile stress is produced in the Germany. Per requests from the German curved region of the specimen when force aerospace industry, DLR wanted to find Product: MSC Nastran is applied. This test method is limited to a preferred layup for composite laminate use with composites consisting of layers Industry: Aerospace L-Angles utilized in aircraft construction. DLR’s goal was to find the most optimized composite of fabric or layers of unidirectional fibers. Benefits: layup to maximize strength and decrease early DLR utilized Patran and MSC Nastran Implicit • MSC Nastran Implicit Nonlinear failure in the composite. Utilizing a standard Nonlinear (SOL400) with 3D elements to (SOL400) provides an accurate unfolding test method for an L-Angle, DLR accurately build models and simulate the method for performing detailed did comparisons against theoretical (hand- L-Angle test. MSC Patran was customized composite laminate analysis calculated), test and finite element methods. utilizing Patran Command Language (PCL) • Results provided by SOL400 DLR chose to do their finite element analysis to allow analytical engineers to be able correlated to within 1 standard with MSC Nastran Implicit Nonlinear (SOL400). to quickly develop L-angle models and deviation of test results reduce the chance for error in analyzing the • By replacing testing with SOL400, Solution many configurations. Composite laminates millions of dollars can be saved were modeled using 3D Hex Elements on a single new aircraft program DLR chose the Breaking Glued Contact and were placed in contact using glued (BCTABLE) method with 1 ply per element contact. Rollers, used to apply loading to and non-equivalenced nodes. This allowed the L-Angle were finely meshed to provide DLR to use the most course mesh to an accurate representation, and placed About MSC Software’s minimize compute time. In addition, Patran in contact with the L-Angle via breaking Composites Solutions was configured with an L-Angle template to glue touch contact. Force-Displacement allow for quick modifications to the model boundary conditions were driven at the Due to today’s use of composite parts and for the many configurations that were tried. ends of a roller uniformly through an RBE3 their highly complex material behaviors, MSC Nastran SOL400 allowed analysts (Rigid Body Element 3) connection. companies are required to do thousands to utilize 3D element to element contact of small tests, leading to a few major tests provided the most realistic simulation model at every level of the validation or testing definition. 3 Major Classes of Layups were Results/Benefits pyramid. These tests are not only extremely generated, with multiple ply orientations In the plot below, the solid black horizontal expensive, but also time consuming defined within each class. Loading was line is the average test results from the many and complex to set up and carry out. applied to the FEA model and on the physical tests conducted. The top and bottom dashed test through a Force-Displacement defintion. lines represent one standard deviation from MSC Software offers a complete Composites DLR chose to use the American Standard test. As can be seen, MSC Nastran Implicit Simulation Solution at all levels of the validation Testing Method (ASTM D 6415-06a STM) Nonlinear (SOL400) correlated to within 1 pyramid, whether it be the material level, the for measuring the Curved Beam Strength standard deviation of test results for many of joint elemental level, or the subcomponent of a Fiber-Reinforced Polymer-Matrix the configurations. The L-angle analysis with level. By enabling virtual testing and reducing Composite. This test method determines MSC Nastran Implicit Nonlinear (SOL400) the amount of physical testing that is needed, the curved beam strength of a continuous is considered to be very accurate and a companies can drastically reduce the cost fiber-reinforced composite material using reasonable method to generate predictive of their aerospace composite design while a 90 curved beam specimen. The curved composite laminate results with accuracy. maintaining the same level of accuracy. For more information, please visit: www.mscsoftware.com/aerosolutions or contact [email protected] Corporate Europe, Middle East, Asia-Pacific Asia-Pacific MSC Software Corporation Africa MSC Software Japan LTD. MSC Software (S) Pte. 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