How about A Butterfly Washer?

Disc Springs, also known as The Belleville Spring Washer, was invented by the French man Belleville. Disc washers (DIN6796 DIN2092 DIN2092 DIN2796) (HDS series) are anti-loose washers designed for bolt and screw connections. It is designed and manufactured according to dIN 6796 for medium or high strength boltand and screw connections.

Supporting load slots and elastic recovery make the HDS series very effective, and bolt pull slack can withstand relaxation due to wear, creep, relaxation, thermal expansion, contraction, or seal compression. The HDS series increases the elasticity of the screws several times, effectively replacing normal spring washers, but does not apply to locking washers, flat washer combinations.

Since the HDS series is a disc spring that can be combined or folded. The combination of the fit mode can increase the amount of deformation of the disc reed group, and the combination of overlapping mode can increase the spring force of the disc reed group. The ideal installation is to flatten as much as possible, the closer to the flattening state, the faster the tension moment increases, and the appropriate bolt pull is required without the need for a torque wrench.