Snap-fitting hook, tapered, rectangle

Use this calculator to determine behaviour and mechanical properties of a snap-fitting hook or cantilever snap. This snap joint is designed to be tapered giving it a thickness of h at the root whilst decreasing the top. Look up the K-factor in underneath table. Calculate deflection force, mating force and maximum strain as a result of a given deflection and geometry h, L, b, K, α. Alternatively one can calculate the thickness h required for the given deflection and the permissible strain εpm.

The force calculations make use of the Secant Modulus Es alternatively called Tangent Modulus. It is the ratio of stress to strain at any point on the curve in a stress-strain diagrame of a material. Next to that the friction coefficient μ is needed. Remember that that it is higher if the same material is used.

In these calculations the counter part is considered rigid.

 h2/h1 K h2/h1 K h2/h1 K h2/h1 K 0.33 2.137 0.50 1.636 0.67 1.338 0.84 1.138 0.34 2.098 0.51 1.614 0.68 1.324 0.85 1.128 0.35 2.060 0.52 1.593 0.69 1.310 0.86 1.118 0.36 2.024 0.53 1.573 0.70 1.297 0.87 1.109 0.37 1.989 0.54 1.553 0.71 1.284 0.88 1.100 0.38 1.956 0.55 1.534 0.72 1.272 0.89 1.091 0.39 1.924 0.56 1.515 0.73 1.259 0.90 1.082 0.40 1.893 0.57 1.497 0.74 1.247 0.91 1.073 0.41 1.863 0.58 1.479 0.75 1.235 0.92 1.064 0.42 1.834 0.59 1.462 0.76 1.223 0.93 1.056 0.43 1.806 0.60 1.445 0.77 1.212 0.94 1.047 0.44 1.780 0.61 1.429 0.78 1.201 0.95 1.039 0.45 1.754 0.62 1.413 0.79 1.190 0.96 1.031 0.46 1.729 0.63 1.399 0.80 1.179 0.97 1.023 0.47 1.704 0.64 1.382 0.81 1.168 0.98 1.015 0.48 1.681 0.65 1.367 0.82 1.158 0.99 1.008 0.49 1.658 0.66 1.352 0.83 1.148 1.00 1.000