The Q-HSH structural exciter can be used to excite structures from 500 Hertz to 10,000 Hertz with 0.8 Newtons (RMS) of force. Specifications are shown in Figure 1.
Figure 1: Specifications for the Q-HSH structural exciter.
The total mass of the exciter is 30 grams, but from a dynamic point of view, the effective mass is about 3 grams.
The exciter is sold in two parts (excluding an amplifier):
Inertial Mass (Q-HSH): Two inertial masses that are placed onto force coupler
Force Couplers (Q-HSH-FC): Six force couplers that are attached to the structure
Examples of the two parts are shown below in Figure 2:
Figure 2: The high frequency mini-shaker requires two parts: a force coupler (Q-HSH-FC) and inertial mass (Q-HSH).
This article contains tips and instructions on using the Q-HSH: 1. Installing the Q-HSH 1.1 Diagram 1.2 Flat Surface 1.3 Mounting the Force Coupler 1.4 Inertial Mass to Coupler 2. Measuring with Q-HSH 2.1 Software: Channel Setup 2.2 Software: Source Setup 2.3 High Pass Filter 3. Removing the Q-HSH 3.1 Removal Tool 3.2 Glue Tool
1. Installing the Q-HSH
This section covers the needed wiring, mounting, and installation of the Q-HSH structural exciter.
1.1 Diagram
The Q-HSH can work with any data acquisition. If using it with Simcenter Testlab software and Simcenter SCADAS hardware, the following connections need to be made (Figure 3):
Figure 3: Connection diagram for using Q-HSH shaker with Simcenter Testlab and Simcenter SCADAS.
Connections include:
Simcenter SCADAS source output to amplifier (ideally the Q-AMP designed to work with Qsource products).
Amplifier output to protection device: To prevent the Q-HSH shaker from being over driven, a protection device is used that will automatically limit any excessive voltage from the amplifier.
Protection device to Q-HSH shaker: There are two wires that connect to the force coupler of the Q-HSH to the protection device.
Q-HSH inertial mass output to SCADAS: The force signal is output from Q-HSH (microdot connection) to a measurement channel on the Simcenter SCADAS. Typically requires a microdot to BNC connection.
The Q-HSH force coupler should be mounted on a flat surface, not a curved surface.
If the test object only has curved surfaces, mount a flat piece of metal on the location to be excited as shown in Figure 4.
Figure 4: Flat metal piece cemented to curved surface of test object.
The Q-HSH shaker can be mounted on this piece of metal.
1.3 Mounting the Force Coupler
It is the force coupler (Q-HSH-FC) base that is attached to the structure being excited as shown in Figure 5.
Figure 5: Mounting the force coupler to test structure.
Attaching the force coupler to the test object is usually done with super glue, which should be used as sparingly as possible.
It is best to prepare the surface of the test object that the force coupler will be attached. This can be done by scratching the surface with sandpaper or a Dremel tool. This causes the super glue to adhere well to the structure and helps with the removal of the force coupler.
With a properly prepared surface, most of the glue will stay on the test object surface rather than the force coupler during removal. Figure 6 shows how glue can accumulate if not used sparingly and without proper surface preparation.
Figure 6: Force coupler on left shows accumulation after repeated use without proper surface preparation and sparing use of glue. A un-used force coupler is shown on the right.
Through careful mounting practices, the force coupler can be used repeatedly and consistently over time.
1.4 Inertial Mass to Coupler
Once the force coupler is mounted, the inertial mass is placed over the force coupler as shown in Figure 7.
Figure 7: The inertial mass is placed over the force coupler.
The inertial mass should "pop" into place over the coupler. A small amount of vaseline can be placed on the lip of the inertial mass to make this easier to do.
Move to either the Acquisition Setup or Scope workbook.
In some of the Simcenter Testlab modules, to use the source outputs on the Simcenter SCADAS select "Tools -> Add-ins" and check on "Source Control".
The Q-HSH is designed to apply forces from 500 Hertz and higher. It is advisable to set the source frequency range to eliminate 500 Hertz and lower as shown in Figure 9:
Figure 9: In many Simcenter Testlab modules, the lower cutoff frequency of the source can be set.
This allows higher force levels to be used for frequencies higher than 500 Hertz.
If the software module being used does not allow a lower cutoff frequency to be set, then see the next section.
The Qsource amplifier (Q-AMP) has a high pass filter knob built into the unit (Figure 10).
Figure 10: High pass filter knob on the Qsource amplifier.
If there is no software setting for the lower cutoff frequency, the amplifier can be used instead.
3. Removing the Q-HSH
Great care should be taken in the removal of the Q-HSH from the test structure. There are two specialized tools included for doing this:
3.1 Removal Tool
To remove the Q-HSH from the test structure, first detach the inertial mass.
In the Q-HSH kit, there is a removal tool that can be inserted into the force coupler as shown in the animation in Figure 11.
Figure 11: Animation of removal tool in use.
This should be done with care and caution. If needed, rock the tool back and forth until the force coupler becomes loose.
3.2 Glue Tool
After removing the force coupler, another tool can be used to clean any glue that accumulated on the force coupler as shown in Figure 12.
Figure 12: Animation showing glue removal tool in use.
This tool is used to prevent glue from accumulating on the force coupler. See previous section for guidance on preparing the surface to minimize the amount of glue that accumulates on the Q-HSH.
There is another part in the Q-HSH kit that can be placed between the force coupler and inertial mass. This allow the inertial mass to be placed about an inch away from the test object surface when in tight quarters.
