A LOW FREQUENCY DATA ACQUISITION SYSTEM FOR DYNAMIC ANALYSIS OF OFFSHORE PLATFORMS

An inexpensive, lightweight Data Acquisition System (DAS) has been developed capable of reproducing low frequency information (equivalent to 10 deg Hz) with an uncertainty of 0.3%. The DAS is a portable, single channel FM recording system comprised of two stages. Stage I consists of a frequency modulator with a constant frequency reference signal and off-the-shelf audio cassette recorder; Stage II consists of a frequency demodulator with flutter compensation. The DAS was designed to record accelorometer output of platform motion and accurately reproduce natural frequency shifts caused by temporal changes in mass and/or structural stiffness. However, any low frequency information of proper voltage, regardless of source is acceptable. The DAS makes low frequency data in general and dynamic offshore platform data in particular more accessible for analysis.

• Corporate Authors:

  Massachusetts Institute of Technology

  Department of Ocean Engineering, 77 Massachusetts Avenue
  Cambridge, MA  United States  02139
• Authors:
  • Mortensen, R G
• Publication Date: 1977-12

Subject/Index Terms

• TRT Terms: Data collection; Motion; Natural frequency; Offshore platforms; Structural analysis
• Uncontrolled Terms: Natural frequencies
• Old TRIS Terms: Platform motions
• Subject Areas: Bridges and other structures; Marine Transportation; Terminals and Facilities;

Filing Info

• Accession Number: 00170520
• Record Type: Publication
• Source Agency: Massachusetts Institute of Technology
• Report/Paper Numbers: MS Thesis
• Files: TRIS
• Created Date: Mar 7 1978 12:00AM