What shape patch is recommended to prevent stress and cracking?

What shape patch is recommended to prevent stress and cracking?

• A. Round patch
• B. Elliptical patch
• C. Square patch
• D. Round or elliptical patch

Answer: (D)

When repairing a cracked or damaged skin, use a patch with a smooth, curved edge because sharp corners create stress concentrations where cracks can initiate and propagate under cyclic loads. A round or elliptical patch provides a gradual transition for the stresses around the patch, distributing them more evenly and reducing peak stress at the edge. Square or rectangular patches have corners that act as stress risers, making cracking more likely. Therefore, round or elliptical patches are recommended to minimize stress and prevent crack growth.

When repairing a cracked or damaged skin, use a patch with a smooth, curved edge because sharp corners create stress concentrations where cracks can initiate and propagate under cyclic loads. A round or elliptical patch provides a gradual transition for the stresses around the patch, distributing them more evenly and reducing peak stress at the edge. Square or rectangular patches have corners that act as stress risers, making cracking more likely. Therefore, round or elliptical patches are recommended to minimize stress and prevent crack growth.