Title: Evaluation of an Alternate Method for Determining Yield Strength Offset Values for Selective Laser Sintered Polymeric Materials

Authors: Chelsey Henry, Keith Rupel, Charles Park, Joseph Costanzo, Cary Kaczowka, Kevin Malik, and Sayata Ghose

DOI: 10.33599/nasampe/s.19.1583

Abstract: Due to the unique characteristics of Additively Manufactured (AM) polymeric materials, typical mechanical strength characterization methods such as those commonly used for traditionally-processed polymers or composite materials can produce results that do not accurately represent material capabilities. In order to characterize mechanical properties of these materials, new test and analysis methods are required. As part of the National Aeronautics and Space Administration (NASA) Advanced Composites Project (ACP), Boeing has evaluated true yield testing as an alternative or complimentary test to 0.2% offset yield testing for determining appropriate yield strength values of polymer materials. Previous testing has shown high strain, low modulus polymer materials such as selective laser sintered (SLS) Nylon 11 at elevated temperatures produce large variations in yield strength. The true yield test method was successful in finding the applied strain level when yield commences and appears to offer an increase in data robustness.

References: 1. Measuring true yield point of plastics, Reporting on developments in material properties for engineering design, Francis Barthelat – Datapoint Labs – Winter ’01, Volume 7.1

Conference: SAMPE 2019 - Charlotte, NC

Publication Date: 2019/05/20

SKU: TP19--1583

Pages: 15

Price: FREE