Accession Number : ADA304069

Title :   A Study of Failure in Carbon/Foam Sandwich Composites with Stress Concentration.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Sistare, Peter J.

PDF Url : ADA304069

Report Date : SEP 1995

Pagination or Media Count : 105

Abstract : Both experimental and numerical studies were performed to understand the failure mechanism of carbon/foam sandwich composite plates with stress concentration. The plates had circular holes and were subjected to bending and compressive loading. Both three-point and four-point bending tests were conducted, For the testing, the foam thickness, the size of the hole, the number of holes, and the hole location were varied. In addition, a finite element analysis was conducted to verify and understand the experimental results. It was found that four-point bending is not an effective test method to evaluate the effects of stress concentration at a hole. Compressive loading is an effective method. A sample without a hole fails at the quarter point due to foam core shear failure. With a hole at the center, the core shear stress at the quarter point increases with increasing hole size. However, the skin bending stress at the hole increases at a faster rate. When the hole size reaches a critical diameter, the failure mode changes to skin bending failure at the hole. (MM)

Descriptors :   *BENDING, *FAILURE(MECHANICS), *SANDWICH CONSTRUCTION, *FOAM, COMPOSITE MATERIALS, FINITE ELEMENT ANALYSIS, BEAMS(STRUCTURAL), STIFFNESS, THESES, COMPOSITE STRUCTURES, CARBON, CORROSION RESISTANCE, HIGH STRENGTH, HOLES(OPENINGS), AEROSPACE CRAFT, FATIGUE(MECHANICS), SKIN(STRUCTURAL), DELAMINATION, COMPRESSIVE PROPERTIES, BENDING STRESS, STRESS CONCENTRATION.

Subject Categories : Laminates and Composite Materials
      Research and Experimental Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE