Transcript J_McPherson_Thesis_presentation_102814.pptx

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; [email protected]
October 2014
1
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; [email protected]
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 2014
2
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; [email protected]
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 2014
3
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; [email protected]
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 2014
4
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
ANSYS APDL Code
Design of Experiments Sample Points
J. McPherson; [email protected]
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 2014
5
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; [email protected]
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 2014
6
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; [email protected]
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 2014
7
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.
J. McPherson; [email protected]
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 2014
8