New Handle CAD DesignLatch Mechanical Analysis

J. Dzionara-Norsen

Handle Redesign

• New handle design to be used with standard crutch frame

• Differences from previous crutch design:– Longer shaft cuffs to account for misalignment

during use– Slide handle onto shaft by removing axillary pad– Modified design handle frame to accommodate

pad– Shorter handgrip to fit standard crutch frame

Handle CAD

Latch Mechanical Analysis

• Cantilevered beam where b=0.2”, h=0.5”• AISI 304 steel• YS = 31,200 psi• F=150 lbf.• F.O.S = 1.73

b

h1”

F

Tearout, Bearing Stress, Shear

• Tearout:

• Bearing Stress: Compressive stress due to surface contact

• Shear of Bolt:

= 2500 psi

= 4167 psi

= 5895 psi

n = 5.3

n = 7.5

n = 12.5

Crutch Misalignment

• Most severe angle is 45 degrees• Maximum y = 1.57”• Handle cuff length and sliding button length

take this into account

𝛼1.57”y