Mechanical Application Brief
According to Phil Korth, a Project Engineer at Harley-Davidson, DADiSP
the graphical display and data management software by
DSP Development Corporation
provides the standard platform for PC-based data
acquisition and analysis required. It standardizes the analysis
capabilities of the various instruments so that data from different
sources may be compared.
The data acquisition instrumentation at the lab falls into three basic
categories; the system provides DADiSP file formats, the system uses a
PC plug-in board, or the system has a GPIB port. The optional GPIB
module, a DADiSP product that supports instrumentation control and data
acquisition, provide the additional flexibility to incorporate the
other data acquisition systems used in the Structures Lab.
Frame Load and Deflection
In testing frame stiffness, data is collected for a torsional load and
up to ten channels of displacement data. The testing procedure
consists of mounting the motorcycle frame rigidly to a bed plate
through a swing arm pivot. The remainder of the frame is allowed to
float on a low friction surface. Linear Variable Differential
Transformers are located geometrically at various points on the
motorcycle frame to accurately measure the deflection of the frame when
the torsional load is applied to the steering head of the frame. The
load and frame deflections are measured and collected in real time.
XY Displacement vs Load
A PC-based data acquisition card is used in connection with DADiSP to
read the data directly into the DADiSP worksheet. The necessary
conversions are then accomplished transforming the analog voltages into
ft-lbs for torque and thousands of an inch for the displacement data.
The DADiSP XY functions plot the individual displacement channels vs.
the torsional load. The linear regression of these XY plots is then
calculated giving a stiffness parameter allowing different frame types
and material to be accurately compared.
DADiSP Builds Stiffness Database
Using DADiSP enabled Harley-Davidson to build a database of the
stiffness parameters of motorcycle frames. This lets them accurately
evaluate how changes made in the frames affect the overall stiffness
characteristics. This becomes an important characteristic in the final
motorcycle, since the stiffness of the frame affects many
characteristics of motorcycle design. "DADiSP provides a standard
platform for laboratory instrumentation in the Structures Lab and
allows the materials which compose a motorcycle to be accurately
characterized," says Phil. These measurements ultimately contribute to
the way a customer feels when riding a Harley-Davidson motorcycle, and
thus how he or she perceives Harley-Davidson Motor Company, the leading