Customer Solutions
Simulating Aerodynamic Loading on an Aircraft Structure using NI Products
Author(s):
Bernard Killeen, Richmond Measurement Services and NDT Services; Joe Manning, Richmond Measurement Services and NDT Services
Industry:
Aerospace/Avionics
Product:
Data Acquisition, Measurement Studio, PXI/CompactPCI
The Challenge:
Determining a method of applying representative aerodynamic loads to a radar dome and recording the resulting strain applied to the structure.
The Solution:
Using National Instruments data acquisition (DAQ) and Measurement Studio software to design and construct a test frame with a novel pressure-control system
Developing a Test Frame and Constructing a Pressure Control System
Richmond Measurement Services (RMS) and NDT Services work together to solve many test & measurement related problems. Chelton Radomes of Stevenage contracted us to determine a method of applying representative aerodynamic loads to one of their radar domes, known as a radome, and record the resulting strain applied to the structure. At RMS and NDT, we developed a test frame and constructed a novel pressure control system.
Pressure Control
We simulated aerodynamic loading by applying pressure into individual pockets placed in contact with the radome surface. We can inflate or deflate each pocket independently of its neighbours in the pressure range 0 to 800 mbar. The test specification required us to control the pressure at 5 mbar and measure to 1 mbar. A specially constructed control cabinet houses inlet and exhaust solenoid-operated poppet valves. We required 40 individual pockets to map the pressure profile. The same enclosure houses pressure sensors so we can accurately monitor the line pressure in each compartment.
At RMS, we have many years of experience using National Instruments products. We implement NI software and hardware with ease to produce robust and reliable systems. Using a PCI-DIO-96 parallel 96-bit parallel digital I/O board, we control the inlet and exhaust valves. We measure manifold and line pressures using a PCI-6071E 64 channel acquisition card. In addition to pressures, we routed the strain gauge signals into the PCI-6071E.
Providing Reliable Test Software
We wrote the control and acquisition software in Visual Basic using NI-DAQ and Measurement Studio. We used a dual-screen PC system running Windows 2000. At RMS, we use a core acquisition system that we developed over many years and add application-specific modules. The user interface consists of a hierarchy of screens, so we can view the fundamental inputs for diagnostic purposes, view the derived data for online analysis, and use the test control screens during the test sequence. Timescales for the test system development were short, so we emphasized manual operation and software reliability rather than advanced functions. The entire test system performed nearly flawlessly during the test schedule, and Chelton Radomes was pleased with the quality of recorded data.
The test requirements document defined loading patterns and load tolerances that should be achieved. The control and recording system that we constructed achieved the required tolerances with few exceptions. Where tolerance was not achieved, Chelton Radomes was readily able to asses the impact on the results. The overall conclusion was that the test objectives were met. With this approach to simulation of aerodynamic loads, Chelton Radomes can execute design evaluation in a cost-effective and timely manner.
For more information, contact:
Bernard Killeen Joe Manning
Richmond Measurement Services NDT Services
www.RichmondMeasurementServices.co.uk www.NDTServices.co.uk.
