PSI - Issue 60

A.M. Sreenath et al. / Procedia Structural Integrity 60 (2024) 256–263 A. M. Sreenath and R. V. Prakash / Structural Integrity Procedia 00 (2024) 000–000

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Three patching configurations were studied, along with the damage treatment discussed. The details of the results are shown in Figure 5. The patching at the bottom gives better results than at the top in all cases. In the case of epoxy-filled specimens, the patch at the bottom does not give any significant advantage. In the case of epoxy-filled composite, a significant change is noticed. The reason may be attributed to the asymmetry of damage patterns due to impact. The filling is done only in a hole with a small diameter hole. So even after the filling, some impact damage may exist outside the filled hole, which could be the reason for the better performance of specimens repaired with the patch at the bottom. The higher load-carrying capacity for the patching on both sides is noticed in all the conditions. Higher load-carrying capacity may be attributed to the higher load-bearing area at the repaired specimen.

Effect of patch configuration on residual strength ( Type of damage: Impact Damage)

Effect of damage treatment on residual strength ( Type of damage: Drilled hole)

0 10000 20000 30000 40000 50000 60000

0 10000 20000 30000 40000 50000 60000

No treatment

No treatment

Epoxy Filled

Epoxy Filled

Chopped Fiber Filled

Chopped Fiber Filled

Failure Load(N)

Failure Load(N)

No Patch One Side Patch

Both Side Patch

No Patch Top Bottom Both

Patch Location

Patch Location

a b Fig. 5: a) Effect of patch configuration on the residual strength of specimens damaged with circular hole and b) Effect of patch configuration on the residual strength of specimens damaged by low velocity impact The effect of different damage treatments is evaluated (refer to Figure 6). It is noted that the epoxy filling at the damaged area does not give any significant improvement. Even a slight decrease in the mechanical properties is also noticed in some cases. Filling with chopped fiber composites does improve the mechanical properties significantly. Epoxy has a very low modulus compared with the composites. A lower modulus will also mean a lower portion of the load is transferred through that member. The chopped fiber-filled epoxy has a higher modulus and could take a more significant portion of the load; hence, the load-carrying capacity may be improved.

Effect of damage treatment on residual strength (Type of damage: Impact damage)

Effect of damage treatment on residual strength ( Type of damage: Drilled hole)

0 10000 20000 30000 40000 50000 60000

0 10000 20000 30000 40000 50000 60000

No Patch

No Patch Top Bottom Both

One Side Patch Both Side Patch

Failure Load(N)

Failure Load(N)

No treatment

Epoxy Filled Chopped Fiber Filled

No treatment

Epoxy Filled Chopped Fiber Filled

Type of filling at the damaged area

Type of filling at the damaged area

a b Fig. 6: a) Effect of damaged area treatment on the residual properties of specimens damaged with circular hole and b) Effect of damaged area treatment on the residual properties of specimens damaged by low velocity impact The single side patches deliver lower repair efficiencies compared with the double sided patches [Aabid (2023)]. Plugging the damaged area with a rigid member will reduce the stress concentration and will increase the strength of