Issue 61

P. S. Joshi et alii, Frattura ed Integrità Strutturale, 61 (2022) 338-351; DOI: 10.3221/IGF-ESIS.61.23

Figure 4: Tensile test setup (a) Test machine (b) Temperature controlled chamber and (c) Specimen fixed in upper and lower grips.

Figure 5: High speed tensile test results for (a) Tensile stress versus Tensile strain (Left) and (b) Ultimate stresses for GE laminates (Right) under varying strain rate and temperature.

R ESULTS AND D ISCUSSION

Temperature and strain rate response - Response of glass epoxy (GE) specimens he stress-strain behavior for Glass Epoxy (GE) specimen is shown in Fig. 5 for all the tested strain rates and temperatures. Fig. 5 (a) indicates that the GE specimens under room Temperature (RT) exhibited a linear response until failure for all the three strain rates 10 -1 , 10 -2 and 10 -3 s -1 with no damage up to highest tested strain rate of 10 -1 s -1 . Beyond this strain rate, the tensile strength suddenly dropped indicating brittle failure in GE specimens. But for the highest tested strain rate of 10 -1 s -1 , the GE specimen has taken higher load, hence higher tensile and ultimate strengths as shown in Fig. 5 (b) when compared other two strain rates used in this research investigations. Further, the test was continued by exposing GE specimens to 250 0 C keeping strain rates same as that under RT conditions. The results indicate onset of plastic deformation followed by a non-linear stress strain response. The primary cause of strain growth at this point was matrix deformation due to rise in temperature. The tensile strength dropped to 88 % of RT value due to plastic deformation T

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