Official Answer
Answer
corrosion fretting ເກີດຂຶ້ນຢູ່ຈຸດຕິດຕໍ່ (crests ແລະຮ່ອມພູ) ລະຫວ່າງພາກຮຽນ spring ຄື້ນແລະຫນ້າການຫາຄູ່ຫຼືລະຫວ່າງ turns ໃນພາກຮຽນ spring ຫຼາຍຫັນ. ການສັ່ນສະເທືອນເຮັດໃຫ້ເກີດການສັ່ນສະເທືອນຈຸນລະພາກ, ທໍາລາຍຊັ້ນອອກໄຊປ້ອງກັນຂອງໂລຫະ (ເຊັ່ນ: $Cr_2O_3$ ໃນສະແຕນເລດ). The resulting fine debris acts as an abrasive, creating pits that serve as stress concentrators $K_t$. Failure analysis often shows 'cocoa' (reddish-brown powder) for carbon steel or black oxide for stainless. Using dry film lubricants (like $MoS_2$) or increasing the preload to prevent relative motion are effective countermeasures.
