compare shock absorber candidate materials

1. Solidworks Simulation
drop test study
Shipping Box
07/29/2016 rev 1
Don Blanchet
3B Associates
dwb3298@outlook.com

2. Task
 Perform an FEA drop test analysis on a
proposed shipping container with
payload.
 Determine the peak acceleration and
displacement from a drop height of 28
inches on to a hard surface.
 Study various elastomer cushioning
materials.
 Solidworks 2015 - Simulation

3. Simplified model
Payload 70 lb
Shock absorber 8 places
Wooden box ½ inch plywood

4. Simplified model
payload removed
21 x 15 x 12 inches

5. Meshed model
top cover removed
Press fit corner
shock absorbers
Drop flat
On bottom
surface

6. Shock absorber materials
material Elastic modulus
psi
Density
Lb/cu-inch
ABS
Polyurethane
440,000 .035
polyethylene 80,000 .031
Nitrile styrene
20% glass filled
950,000 .039

7. Drop animation case
removed

8. Deformation at impact
40x scale

9. Deformation at impact
40x scale

10. Deformation at impact
40x scale

11. Deformation at impact
40x scale
Absorbers are not bonded to the
payload or case

12. Payload displacement
at impact
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
aluminum glas styrene ABS Polyethylene
Deflection of Payload , inches

13. Shock acceleration time response
during the first millisecond, G’s
-30000
-20000
-10000
0
10000
20000
30000
40000
aluminum glas styrene ABS polyethylene

14. Shock time response in the first
millisecond
Best candidate polyethylene
-30000
-20000
-10000
0
10000
20000
30000
40000
aluminum polyethylene

15. Summary
 As expected the shock absorber with the lowest
modulus of elasticity provides the lowest payload
shock response at impact.
 The maximum deflection does not exceed 10% of
the absorber thickness of 0.50 inches.
 Performing an FFT on the shock time response will
convert it to the frequency domain which can be
used as an SRS for detailed payload stress analysis
during the drop event.