Page 24 - Shock and Vibration Overview

Equipment Setup

c. Double Sided Tape
Double sided tape is often thought to not be strong or stiff enough to be used
as an effective mounting method for accelerometers. They do offer the lowest
frequency response of all the adhesives but for many applications it is still
plenty effective enough. Midé’s has had good luck with the 3M 950 adhesive
transfer tape for its Slam Stick products (a 5 yard roll is actually included with
each unit). Endevco’s study found that the thickness of the adhesive is the
most important factor and this is only 0.005” thick (0.1 mm). If the 950 tape is
adequately compressed then there is no discernable difference in the Slam

Stick’s performance compared to mounting with bolts. The downside of this
particular tape is that it’s quite tacky and can be difficult to remove. 3M offers
an adhesive eraser wheel which is effective at removing this tape and other
adhesives.

3) Adhesive Mounting Pad
Adhesive mounting pads offer the very high frequency response of adhesives and
stud mounting; but allow the engineer to easily swap out accelerometers. For large
structures when you may be doing modal analysis it is much easier to instrument the
structure with adhesive mounting pads first (no wiring, and less expensive) then
attach the accelerometers for your test. At the end of testing the accelerometers can
easily be taken off and brought to the next test. If, after analyzing the data, the team

determines more testing is needed then having the mounting pads remain on the
structure ensures that the tests can be repeatable. Adhesive mounting pads also help
prevent epoxy from damaging expensive accelerometers. Here are some
accelerometer mounting bases from PCB; but there are many accessory options out
there.

4) Magnetic Mounting Base
For ferrous magnetic structures a magnetic mounting base allows easy and mess-free
accelerometer mounting. There are two types of magnetic bases: flat, and curved;
flat offers the best frequency response. You should use caution with magnetic
mounting bases to not damage your structure or injure yourself. But these are a
great solution for short term testing applications. Here are some accelerometer
magnetic mounting bases from PCB.

5) Hand Held or Probe Tip
Some applications can be difficult to reach for proper mounting and/or have sensitive
coatings or materials that prevent adhesives or bolting. A probe tip can be utilized to

24 of 69