is a dip brazed aluminum assembly more rugged than a similar design using screw fasteners?

1. Mercury Systems Proprietary
Solidworks Simulation
Bolted vs. Dip Brazed
aluminum side panel
stiffness study
03/15/2014
Rev B
Don Blanchet
Consulting Engineer, © 3B Associates
Force Fabrication
Oxnard , CA

2. Client request
n I don’t want to invest in extra cost to
outsource assemblies to aluminum dip
or vacuum brazing houses.
n Having low labor grade people screw
them together is less expensive and
just as strong.
n Can you show this with FEA ?

3. Model
# 6-32 screws
Fixed bottom edge
End
pressure
load

4. Model – overall 6 x 9 inches
frame
Thin .062 cover
Back view
End Loading should
Cause diagonal
Racking and twisting

5. Loading of bolted cover
Max displacement
.00125 inches
un-deformed

6. Detailed displacement
un-deformed
Cover separation
Between screws

7. Dip Brazed cover
(screws removed)
same loading
Max displacement
.000158 inches
Braze joint

8. Conclusion
n The brazed cover adds significant stiffness to this
assembly over the design with very closely spaced
#6-32 hardware. It is a better structural fabrication
method.
n The flexibility ratios are:
– No cover = 9.0
– Screw mounted cover = 7.0
– Brazed cover = 1.0