PSI - Issue 71

Deepak Kumar et al. / Procedia Structural Integrity 71 (2025) 380–387

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and the force reaction also follows the same trend as energy absorption given in Table 6. The same trend follows when the mass of the impactor increased, the value of absorbed energy and force reaction also increased in all laminate configurations. From the above data it is found out that the configuration which has the highest energy absorption is CCCC with an absorbed energy of 73.20 J followed by CFSC laminate with absorbed energy of about 72.70 J. Then follows the CFFC laminate with absorbed energy of about 60.51 J, and CSSC with absorbed energy of 50.9 J and then the natural fiber laminates of FFFF and SSSS with an absorbed energy of 22.62 J and 15.56 J, respectively. Both energy absorption and force reaction for CFSC laminate configuration show similar trend in Fig. 4. For all velocities there is a rapid increase in absorbed energy and force reaction followed by a sharp decline within approximately 1-2 ms as like in CCCC, CFFC, and CSSC laminates. Plate is rebounding after impact and all the impact energy gets converted into elastic energy of the plate. While in Fig. 5 both the absorbed energy and force reaction are comparable to the CCCC and CFFC case but it is higher than CSSC case. This shows hybridization effects are much stronger on an impactor higher mass. This also highlights the composite's ability to absorb more energy when subjected to higher impact forces, which is essential for applications requiring high impact resistance.

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Fig. 4: CFSC laminate for 0.412 kg mass (a) absorbed energy vs time (b) force reaction vs time.

In Fig. 6 both energy absorption and force reaction show similar trend as that with the impactor of 5 kg. However, after reaching maximum absorption, some of the stored elastic energy within the composite may be released. The internal damping mechanisms may dissipate energy thus leading to a stabilization or slight decrease in the absorbed energy. 4.1. LVI analysis according to ASTM standards As per the ASTM D7136/D7136M–15 standards for impact testing of composite specimens, all the specimens are rectangular, measuring 150 mm by 100 mm, with each ply having a thickness of 0.25 mm. All the 6 different composite laminate configurations considered for study are centrally impacted by a spherical steel impactor with a hemispherical striker tip of 16 mm radius and a drop weight of 5.5 kg as per the ASTM standards.

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Fig. 5: CFSC laminate for 5 kg mass (a) absorbed energy vs time (b) force reaction vs time.