A Comparison of Low-Velocity Impact and Quasi-Static Indentation

Abstract

Approved for public release; distribution is unlimited.ii REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)December 2012 ARL-TR-6272 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES* Bowhead Science & Technology, 4900 Seminary Rd., Ste. 1200, Alexandria, VA 22311 ABSTRACTThe purpose of this investigation is to assess the potential interchangeability of key material response metrics as measured using quasi-static indentation (QSI) and low-velocity impact (LVI). This report compares the response of a S2/SC-15 glass /epoxy composite material subjected these two test methods. Specimens of 102 × 152 × 5.5 mm were quasi-statically indented at load rates in the range of 1.2 to 50 mm/min. Differences in material response over this range of loading rate were found to be negligible. The average value of peak input energy calculated from these QSI tests was used as the impact energy for subsequent LVI tests of identical specimens. Material tested using LVI (3.41 m/s velocity) exhibited higher initial stiffness and absorbed energy but with slightly lower maximum force and displacement values compared to material tested with QSI. Thirty QSI and LVI specimens were then evaluated with compression after impact (CAI) testing, and all specimens exhibited equivalent CAI strengths. Lightbox and cross-section analyses showed that material tested under LVI exhibited significantly less delamination and significantly more intralaminar fracture compared to QSI. For these reasons, LVI and QSI data are not interchangeable for this material system. SUBJECT TERMS

Failure mechanisms and damage evolution of laminated composites under compression after impact (CAI): Experimental and numerical study

“…Many researchers have investigated low-velocity impact and equivalent quasi-static indentation loading [9][10][11]. By contrast, systematic studies of damage tolerance in CAI tests are far fewer in number.…”

Quasi-Static Indentation and Low-Velocity Impact Response of Aramid/Epoxy Composites

“…Nettles and Douglas [11] and Lee and Zahuta [13] also state that these two tests induce similar failure mechanism, with very similar damages and force × displacement curves, for carbon/epoxy composites. On the contrary, Lawrence et al [14] and Spronk et al [15] reported different damages and curves from QSI and drop-weight tests for glass-S2/epoxy, carbon/epoxy and glass/polyamide composites.…”

Investigation of mechanical behavior of glass fiber reinforced extruded polystyrene core material composites

“…Since there are many different production parameters in impact tests, tests were performed according to ASTM D7136 standard at a constant energy of 50 joules. 56 Production parameters were compared by considering the force deformation curves as test results. The specimen dimensions are 100 mm × 100 mm square.…”