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Laboratory Memorandum (National Research Council of Canada. Institute for Ocean Technology); no. LM-2005-09, 2005
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Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Carriage link trusses
National Research Council Canada Institute for Ocean Technology Conseil national de recherches Canada Institut des technologies oc ´eaniques
Laboratory Memorandum
LM-2005-09
Carriage Link Trusses
T. Slade
May 2005
DOCUMENTATION PAGE REPORT NUMBER
LM-2005-09
NRC REPORT NUMBER DATE
May 2005 REPORT SECURITY CLASSIFICATION
Unclassified
DISTRIBUTION
Unlimited TITLE
CARRIAGE LINK TRUSSES
AUTHOR(S)
Trent Slade
CORPORATE AUTHOR(S)/PERFORMING AGENCY(S)
Institute for Ocean Technology, National Research Council, St. John’s, NL PUBLICATION
SPONSORING AGENCY(S)
Institute for Ocean Technology, National Research Council, St. John’s, NL IOT PROJECT NUMBER
2064
NRC FILE NUMBER
KEY WORDS
Truss, links, carriage
PAGES iii, 15
FIGS. TABLES
SUMMARY
Truss type links were designed and fabricated to connect the service carriage in the towing tank to the main carriage.
ADDRESS National Research Council Institute for Ocean Technology Arctic Avenue, P. O. Box 12093 St. John's, NL A1B 3T5
National Research Council Conseil national de recherches Canada Canada Institute for Ocean Institut des technologies
Technology océaniques
CARRIAGE LINK TRUSSES
LM-2005-09Trent Slade
TABLE OF CONTENTS
Design ... 1
Installation... 2
Maximum Stress (4200 lbs) ... 3
Maximum Displacement (load 4200 lbs)... 4
Sag with 20 Kg in Middle... 5
Natural Frequency Mode1 ... 6
Natural Frequency Mode2 ... 7
Natural Frequency Mode3 ... 8
Natural Frequency Mode4 ... 9
Natural Frequency Mode5 ... 10
Truss... 11
Adapter... 12
Carriage Mount ... 13
Mirror carriage Mount ... 14
Design
Truss Type Links to connect the Towing Tank Carriage to the Service Carriage
A full-scale life raft was to be towed, tracked and stopped at the end of each run in IOT’s Towing Tank. The service carriage is to be placed behind the carriage and attached with truss type links. The ideal situation would have the service carriage placed 12m back from the end of the carriage, since the tank is 12m wide to give a 12m x 12m square. The design for these links has incorporated the increased load of a future proposed wind carriage adaptation. Design criteria – able to with stand 6265Kg of dead load, with max deceleration of 3m/s^2. Maximum load on each link =6265Kg*3m/s^2 = 18796N / 2 = 9397N.
The truss connections are to be pinned at each end so the following formula applies:
Euler’s Formulae for struts hinged at both ends P = pi^2 E I P = 18.8 Kn
--- Material Aluminum E = 69E9 GPa L^2 L = 12m
Solving for I = 3.98 m^4 or 9.55 in^4 note 1m^4 = 2.4e6 in^4 Each link needed 9.55 / 2 = 4.78in^4
Section chosen has an I = 113in^4, the section chosen has a I value of 23 times what was needed. This was required in order to achieve a natural frequency above 10 Hz.
A concept was created and an Algor model was generated to analyze the stress, displacement, sag, and the modes of Natural Frequency.
Both steel and aluminum was investigated, Aluminum was chosen because it was lighter, the natural frequency was about the same, and the material cost was less.
The 12m section was to be divided into three 4m sections for ease of moving the pieces around and for future use if 12m was too long.
Directory location:
Cad_User\projects\42_2064_16_Life Raft Operational Performance/Phase 3 – CWTT/TRUSS.CKD
Installation
In order for the Carriage Mount to be removable for the Towing Tank Carriage, mounting plates had to be welded on. The Carriage Mounts could then be bolted to the carriage via the mounting pads. Six 4m sections of Truss’ were fabricated, 3 for each side and an Adapter to link these truss’ to the service carriage.
