Search NASA⌕ Search

SEARCH · Search NASA

Results for “single cantilever beam (SCB) test”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

4 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Characterizing Face Sheet/Core Disbonding Using the Single Cantilever Beam Test: Results from an International Round Robin

Test results from an international round robin are presented. The single cantilever beam (SCB) test was used to characterize face sheet/core disbonding in sandwich components in an effort to help standardization. Each of the seven participating laboratories performed a set of five baseline tests using the same protocol, however, using their own specific equipment. In addition, each laboratory performed two sets of tests with altered tests conditions which included using a test fixture with a translating carriage and performing the tests with different loading and unloading speeds. The orientation of the disbond front with respect to the honeycomb core cells was varied and the effect on the fracture toughness was also studied. Additional factors that could influence test results were investigated, such as the use of a saw cut starter disbond as an alternative to Teflon® release film, and the effects of using a face sheet doubler to increase the bending stiffness. For each set of tests, summary results such as load/displacements plots, observed disbond growth location and calculated energy release rates are reported and a comparison of results between labs is presented. Critical strain energy release rate measurements from SCB tests are also compared with measurements made from an alternative test, namely the double cantilever beam with uneven bending moments (DCB-UBM) test, which has been studied extensively at the Technical University of Denmark and proposed as a mixed-mode test standard. A set of recommendations are made with respect to improving the SCB test and a path to standardization is presented.

Ronald Krueger↗
NASA NTRSDate not supplied

Computational Assessment of the Opening Mode Facesheet-to-Core Fracture Toughness of a Thin-Gage Facesheet Sandwich Structure

The single-cantilevered beam test (SCB) is currently being considered for standardization for measuring the opening mode fracture toughness of sandwich structures subjected to facesheet-to-core separation. At present, the Area method is considered the benchmark method for determining energy required to propagate the crack. This method is problematic since it requires periodic unloading and cannot be evaluated instantaneously. Therefore, a method is needed to accurately and instantaneously calculate opening mode fracture toughness. In previous work, SCB tests with thin-gauge facesheets were performed to compare the J-integral approach to data reduction methods including the Modified Beam Theory (MBT) and the Area method. Large deviations (over 10%) in the calculated fracture toughness were observed between the J-integral and MBT for large displacements. In this study, a simulated SCB experiment using a virtual crackclosure technique was performed to assess the previously observed discrepancies. The predicted load displacement response, the predicted angle at the load application point, and the predicted crack growth results are in good agreement (within 5%) with the corresponding experimental data. Using the predicted load and angles, the predicted J-integral is in good agreement (within 10%) with the experimentally obtained solution. Using the MBT approach, the previously observed deviations in the fracture toughness were determined to be associated with the empirical extrapolation procedure to estimate the crack-root rotation correction from nonlinear compliance curves. The nonlinear compliance is determined to be associated with large displacement effects observed within the predicted and experimental results.

Sandwich Composite↗
NASA NTRS2010

Sizing Single Cantilever Beam Specimens for Characterizing Facesheet/Core Peel Debonding in Sandwich Structure

This paper details part of an effort focused on the development of a standardized facesheet/core peel debonding test procedure. The purpose of the test is to characterize facesheet/core peel in sandwich structure, accomplished through the measurement of the critical strain energy release rate associated with the debonding process. The specific test method selected for the standardized test procedure utilizes a single cantilever beam (SCB) specimen configuration. The objective of the current work is to develop a method for establishing SCB specimen dimensions. This is achieved by imposing specific limitations on specimen dimensions, with the objectives of promoting a linear elastic specimen response, and simplifying the data reduction method required for computing the critical strain energy release rate associated with debonding. The sizing method is also designed to be suitable for incorporation into a standardized test protocol. Preliminary application of the resulting sizing method yields practical specimen dimensions.

Ratcliffe, James G.↗
NASA NTRS2010

Sizing Single Cantilever Beam Specimens for Characterizing Facesheet/Core Peel Debonding in Sandwich Structure

This technical publication details part of an effort focused on the development of a standardized facesheet/core peel debonding test procedure. The purpose of the test is to characterize facesheet/core peel in sandwich structure, accomplished through the measurement of the critical strain energy release rate associated with the debonding process. Following an examination of previously developed tests and a recent evaluation of a selection of these methods, a single cantilever beam (SCB) specimen was identified as being a promising candidate for establishing such a standardized test procedure. The objective of the work described here was to begin development of a protocol for conducting a SCB test that will render the procedure suitable for standardization. To this end, a sizing methodology was developed to ensure appropriate SCB specimen dimensions are selected for a given sandwich system. Application of this method to actual sandwich systems yielded SCB specimen dimensions that would be practical for use. This study resulted in the development of a practical SCB specimen sizing method, which should be well-suited for incorporation into a standardized testing protocol.

Ratcliffe, James G.↗