Official Answer
Answer
ມຸມແຫຼມຢູ່ດ້ານລຸ່ມຂອງຮ່ອງວົງແຫວນທີ່ຍຶດຖືເປັນຕົວເພີ່ມຄວາມກົດດັນທີ່ສໍາຄັນ, ແຕ່ລັດສະຫມີຂະຫນາດໃຫຍ່ສາມາດນໍາໄປສູ່ຄວາມລົ້ມເຫຼວຂອງວົງ. ຖ້າລັດສະໝີ $r$ ຢູ່ດ້ານລຸ່ມຂອງຮ່ອງໃຫຍ່ເກີນໄປ, ມັນປ້ອງກັນບໍ່ໃຫ້ວົງແຫວນນັ່ງກັບຝາຮ່ອງ. This creates a 'ramp' effect: when an axial load is applied, the ring is forced up the radius, leading to a radial expansion and eventual 'pop-out' failure. The standard engineering rule is that the maximum radius on the groove should not exceed $0.1$ times the ring thickness $t$. If a larger radius is required for shaft fatigue strength, a 'back-up washer' with a sharp corner must be placed between the component and the ring to ensure even load distribution.
