|
Laser Scanning
Supports Fast and Accurate Stress Analysis Simulations
The Company:
A
consulting firm that solves difficult engineering problems through
analysis, materials and performance testing, troubleshooting,
monitoring, and maintenance.
The company serves both OEMs and end users in many industries including
pump, compressor, and turbine manufacturers, biomedical, military
components, and electronics. They also develop software to simulate and
analyze stress, failure, and vibration, and to troubleshoot and predict
problems.
The Challenge:
A
US company with a plant in Mexico contacted the consulting company about
a problem with the forged metal turbine blades in their axial flow
compressor. Many of the forged blades exhibited cracking, and their
engineers could not determine the cause. The client did not possess the
blades’ CAD drawings, so they were not able to perform simulated stress
analysis with the exact CAD models.
The consulting company was tasked with determining why the blades
cracked and how to remedy the problem. The senior engineer on the
project knew that in order to perform the appropriate stress and
vibration testing they needed to recreate the CAD solids model perfectly
by reverse engineering the actual physical blade.
The Solution:
The engineer, who had successfully used GKS Inspection Services, a
division of Laser Design, Inc., in Minneapolis, MN, for reverse
engineering a part in the past, sent four sample blades to Larry
Carlberg, service bureau manager at GKS for scanning. The surfaces of
the blades were irregular, with curves, scallops, and cupped shapes
which vary in thickness from the base to the tip
With over 25 years in the business, GKS metrologists have experience
with all kinds of custom projects. Carlberg explained the approach he
would take and how to address the issues of the irregular surfaces.
Because the laser scanning system projects a line of laser light onto
surfaces while cameras continuously triangulate the changing distance
and profile of the laser line as it sweeps along, the problems of
missing data on an irregularly shaped surface is eliminated.
 The
system measures fine details and captures complex freeform geometry so
that the object can be exactly replicated. Laser scanners quickly
measure articles, picking up tens of thousands of points per second, and
generating huge numbers of data points without the need for templates or
fixtures.
Carlberg used the Laser Design Surveyor 3500 system with the RPS-450
laser probe because of the parts’ accuracy needs. “We scanned the
parts very quickly,” said Carlberg, “since
we have done this type of work many times for various clients and have
good experience in collecting point data.”
The most challenging part of the project was not in scanning the parts,
but in creating an exact model that was acceptable to the consulting
company. Carlberg explained, “The complex curves around the base of the
blade, normally called a fillet radius, are constantly changing as they
proceed around the blade. Defining this shape in as Pro/E entities is
very difficult due to the limitations of the software.” The software
code simply does not contain infinite possibilities for defining
curves.
Carlberg continued, “Curves that change in three directions are nearly
impossible to define in traditional CAD. We solved this problem by
importing the complex curve geometry from the surfacing package Geomagic
Studio. Although the customer cannot easily modify this imported
geometry, it does provide an accurate
representation of the real part.”
With the “reconditioned” scan data from GKS, the engineer created
computer models of the blades and imported them into the company’s
analysis software. He then applied the physical properties to the
computer models for stress analysis. The density was applied to within
a few percentages for the weight of the blades, which is an acceptable
variance. “We couldn’t have done this with any confidence without
having the computer-generated part.”
The Results:
“The quality of GKS’s work was good. We were able to determine why the
compressor blades were failing. The scanning technique functioned really
well in giving us reliable data to work with,” commented the engineer.
After importing the scan files of the blades into the solid modeler
software ProEngineer, the consulting company’s engineers performed
finite element analyses. They were able to recommend changing the blade
material to correct the cracking problem based on the test results. The
senior engineer concluded, “GKS provided an important link to bring the
actual physical part into a simulation.”
For additional information about how GKS Inspection Services can improve
your manufactured product, save you money and decrease your development
time, call Larry Carlberg at 952-252-3433 or send email to
measure@gks.com or visit GKS Inspection Services’ web site at
http://www.gks.com.
|
