The main application is the large scale modal testing and analysis of space components, including the Space Shuttle and International Space Station modules. In the coming months NASA is scheduled to perform a survey of the X33 Reusable Launch Vehicle (RLV). The experimental X-33 is based on a lifting body shape and is a remotely-piloted, sub-orbital vehicle, capable of altitudes up to 80km and speeds of Mach 15.
Because of their size and the huge aerodynamic forces, such structures need to be characterized in great detail. According to Tim Driskill, Senior Test Engineer, modal surveys typically use around 450 triaxial transducers to obtain a sufficient spatial resolution - making 1350 channels in all. It takes around a week to mount the structure in the test fixture, another week to instrument it, and another week for the measurement and data validation.
One handy feature of the SCADAS III will enable operators to know when a transducer is connected properly: as the circuit is made, a LED on the front panel switches from red to green - giving an immediate feedback of a good connection, visible from far away.
Broadband random is used to excite the structure at relatively low levels, usually by three to four electrodynamic shakers. MIMO Stepped sine techniques are occasionally used to describe the structural modes in greater detail - long time readers of the LMS Newsletter may recall an article back in 1991 which covered the non-linear characterization of the Space Station Common Module. The results are then used by the analysis group for FE model correlation and updating.
About LMS International
LMS is an engineering innovation partner for companies in the automotive, aerospace and other advanced manufacturing industries. LMS enables its customers to get better products faster to market, and to turn superior process efficiency to their strategic competitive advantage. LMS delivers a unique combination of virtual simulation software, testing systems, and engineering services. We are focused on the mission critical performance attributes in key manufacturing industries, including structural integrity, handling, safety, reliability, comfort and sound quality. Through our technology, people and over 25 years of experience, LMS has become the partner of choice for most of the leading discrete manufacturing companies worldwide. LMS, a Dassault Systèmes Gold Partner, is certified to ISO9001:2000 quality standards and operates through a network of subsidiaries and representatives in key locations around the world.
