3D profilometry for turbine blade shape profiling

• Main Author: Chng, Sian Shing.
• Other Authors: Anand Krishna Asundi
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Manufacturing::Metrology
• Online Access: http://hdl.handle.net/10356/40097
• Institution: Nanyang Technological University

The rising need for fast and accurate 3D profile measurements has been a concern over the years. There is an increase in popularity for 3D profile measurement by optical technique known as ''Fringe Projection Profilometry''. It allows for fast 3D profile measurement with totally no contact with the measuring object. The Compact Fringe Projection Profilometer is designed to carry out 3D profile measurement on engineering components such as turbine blades conveniently. It consists of a CCD camera and a digital light projector as the measuring apparatus which are connected to a personal computer. The camera and projector will take command through the interface of the software known as ''Fringe''. This profilometer will require two types of calibrations known as ''Out of Plane Calibration'' and ''Camera Calibration''. A comparison is to be made between the Compact Fringe Projection Profilometer and Laser Displacement Sensor System in term of factors such as measuring time, repeatability, measurement range and setup cost. The Laser Displacement Sensor System, LDSS, is another system which can also perform the task of 3D profile measurement such as turbine blades. It consists of a CCD laser displacement sensor, a motorized translation stages, a multi functional controller, a data acquisition system, a multi functional controller and a computer for processing. This system performed 3D profile measurement based on point by point scanning by the CCD laser displacement sensor. The supporting software for this system will be LabView. Both systems were evaluated in term of repeatability through measurements of turbine blades. An evaluation test known as "Merging Test" was conducted. A line on the turbine blade and hemisphere were to be measured by the two systems and the profiles were merged together. The main attention will be mainly on how well the profiles can be closely fitted together. The final result concluded that the designed Compact Fringe Projection Profilometer was able to carry out turbine blades profile measurement with high repeatability and able to provide 3D profile results that were comparable to LDSS.