J. McPherson; October Sensitivity of Carbon/Epoxy Laminates to Void Content A Thesis Proposal Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute, In Partial Fulfillment of the Requirements for the degree of MASTER OF SCIENCE in MECHANICAL ENGINEERING

J. McPherson; Thesis Proposal Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute, In Partial Fulfillment of the Requirements for the degree of MASTER OF SCIENCE in MECHANICAL ENGINEERING October Sensitivity of Carbon/Epoxy Laminates to Void Content Introduction/Background Fiber reinforced composite materials are used in wide variety of applications including aerospace, automotive, and defense industries. A layup consisting of several plies, each oriented at a specific angle and with a desired matrix to fiber ratio is necessary to achieve required directional strength characteristics. Parameters of manufacturing process induces damage to the part (delaminations and voids) Manufacturing defects have detrimental effects to mechanical properties of fiber reinforced composite materials

J. McPherson; Thesis Proposal Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute, In Partial Fulfillment of the Requirements for the degree of MASTER OF SCIENCE in MECHANICAL ENGINEERING October Sensitivity of Carbon/Epoxy Laminates to Void Content Problem Description Experimental studies have been performed to quantify the effects of defects relative to material strength and stiffness properties Generally, parts are scraped if void content exceeds acceptable levels (>1-5% in some cases) Time and cost of the raw materials is wasted Analytical/numerical methodologies to simulate void content and corresponding structural behavior do not exist

J. McPherson; Thesis Proposal Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute, In Partial Fulfillment of the Requirements for the degree of MASTER OF SCIENCE in MECHANICAL ENGINEERING October Sensitivity of Carbon/Epoxy Laminates to Void Content Methodology/Approach Review available experimental data for Carbon/Epoxy laminates containing voids Derive functions describing void effect on tension/compression modulus for tested material Apply functions to textbook material properties Analytical sensivity studies using Finite Element Method: Design of Experiments Local and random distribution of voids Unidirectional, cross ply, angle ply laminates Comparison between shell and solid element formulation

J. McPherson; Thesis Proposal Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute, In Partial Fulfillment of the Requirements for the degree of MASTER OF SCIENCE in MECHANICAL ENGINEERING October Sensitivity of Carbon/Epoxy Laminates to Void Content Progress/Results Experimental data shows void affect tension and compression moduli differently. Linear functions defined to describe experimental data Design of Experiments sample points defined ANSYS APDL code developed to implement material modifications Design of Experiments Sample Points ANSYS APDL Code

J. McPherson; Thesis Proposal Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute, In Partial Fulfillment of the Requirements for the degree of MASTER OF SCIENCE in MECHANICAL ENGINEERING October Sensitivity of Carbon/Epoxy Laminates to Void Content Progress/Results ~2x displacement difference with 5% voids Load redistributes around localized regions of voids Voids cause significant stress increase due to load redistribution Effect of 5% Voids Localized Voids Randomly Distributed Voids

J. McPherson; Thesis Proposal Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute, In Partial Fulfillment of the Requirements for the degree of MASTER OF SCIENCE in MECHANICAL ENGINEERING October Sensitivity of Carbon/Epoxy Laminates to Void Content Milestone/Deadline List 1.Compare/review experimental data for Carbon/Epoxy laminates [August 2014] COMPLETE 2.Document findings from experimental testing [August 2014] COMPLETE 3.Construct simply supported plate model using shell elements with ANSYS Finite Element Software [September 2014] 4.Derive linear functions for effect of void content on tension and compression modulus [October 2014] COMPLETE 5.Define and complete Design of Experiments [October 2014] 6.Define and complete localized and randomly distributed voids [October 2014] COMPLETE 7.Define and complete cross ply and angle ply study [October 2014] COMPLETE 8.Create solid element Finite Element Model for verification of shell model predictions [October 2014] IN PROGRESS 9.Document results of sensitivity study and finalize thesis documentation [November 2014] IN PROGRESS

J. McPherson; Thesis Proposal Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute, In Partial Fulfillment of the Requirements for the degree of MASTER OF SCIENCE in MECHANICAL ENGINEERING October Sensitivity of Carbon/Epoxy Laminates to Void Content Expected Outcome Develop a methodology for modeling the effects of void content in a given composite material with shell elements and layup properties specific to the region of defect Enable an analyst to include global defects within a structural assessment and minimize/eliminate the need for 3d modeling Automate the process for material property modifications and spatial application within the finite element model.