Structural Analysis

Solidworks FEA Simulation Advanced Dynamics

Date: Jan 14, 2015

D. Blanchet

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Reference image Typical electronics Assembly

Lockheed Martin CEEU

• Total Assembly weight = 152 lbs

• Material 6061-T4 Dip Brazed Aluminum

– Yield strength = 21,000 psi

– Ultimate strength = 35,000 psi

• Load Cases

– Random Vibration

– Shock

– Inertial Acceleration

• Nominal part dimensions are used in the analysis

Assumptions – custom assembly concept

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Simplified SW model Electronics Assembly

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Solidworks FEA meshed model (900,000 D.O.F.)

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Solidworks meshed model covers removed

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Backplane

Solidworks FEA Detailed fine mesh

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High Stress Zone At Mounting Foot

Braze Joint

Random Vibration test level D 8.92 Grms

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Applied individually to 3 axes.

Random Vibration Results – stress side to side

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3 sigma Von Mises

Stress = 4,500 psi

Random Vibration Results – displacement side to side

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3 sigma Displacement

.012 inches

Random Vibration Results - Summary

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Direction input PSD

3 sigma Displacement

3 sigma Stress

psi

Factor Of

Safety*

Side-to-side 8.92 Grms .012 (plenum)

4,500 (foot)

4.6

Up - down 8.92 Grms

.014 (plenum)

6,000 (foot)

3.6

Front-to-back 8.92 Grms

.012 (IO cage cover)

3,900 (foot)

5.4

* Factor of safety based on a Yield Strength of 21,000 psi

Shock input, 6 directions

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Shock response max stress @ mounting foot downward direction

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Conclusion: Stresses from Shock pulses

Are insignificant

Shock Response max displacement downward shock

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Max displacement .002 inches

Plot magnification = 240,000 X

Results: Acceleration / Simultaneous Inertial Loads G’s (m/sec sq)

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Load Case

Forward Up

Down Side Max Stress

Mounting Feet (psi)

Material Strength

(psi)

Factor of

Safety

Limit Load

2.0 (19.6)

3.07 (30.1)

- 1.7 (16.7)

2,500 21,000 8.4

Ultimate Load

3.0 (29.4)

4.6 (45.1)

- 2.5 (24.5)

3,250 35,000 10.8

Limit Load

2.0 (19.6)

- 6.0 (58.8)

1.7 (16.7)

4,500 21,000 4.7

Ultimate Load

3.0 (29.4)

- 9.0 (88.2)

2.5 (24.5)

7,800 35,000 4.5

side

up

forward

Results: Acceleration / Simultaneous Inertial Loads G’s (m/sec sq)

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Load Case

Forward Up

Down Side Max Stress

Fiber Bracket

(psi)

Material Strength

(psi)

Factor of

Safety

Limit Load

2.0 (19.6)

3.07 (30.1)

- 1.7 (16.7)

250 11,000 44

Ultimate Load

3.0 (29.4)

4.6 (45.1)

- 2.5 (24.5)

350 27,000 77

Limit Load

2.0 (19.6)

- 6.0 (58.8)

1.7 (16.7)

450 11,000 24

Ultimate Load

3.0 (29.4)

- 9.0 (88.2)

2.5 (24.5)

675 27,000 40

side

up

forward Max displacement = .002 inches

Results: mounting bolt analysis 8 places

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• The electronics assembly design concept is structurally adequate for the specified environments.

• The maximum stresses and displacements occur during combined acceleration.

• The stresses are below the yield point of 6061-T4 for all load cases.

• Shock Load stresses are Insignificant.

• The assembly main mounting bolts need to have a yield strength >= 100,000 psi

Conclusions

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