HMS Dauntless stays on TRaC

HMS Dauntless, the second of the Royal Navy's class of air defence destroyer arrived at Portsmouth Naval base for the first time in December. Dauntless is one of six new Type 45 destroyers which will provide the backbone of the UK's naval air defences for the next three decades.

The impressive Sampson Radar from BAE Systems Integrated System Technologies is a striking feature, and was a particularly interesting project for TRaC in supporting BAE Systems Integrated System Technologies with qualification through means of vibration testing, finite element analysis and modal testing.

Image courtesy of BAE Systems Integrated System Technologies

Owing to the size of the unit under test (7m and 6 tonnes), the process for qualification went beyond conventional testing, and TRaC Employed a number of physical and theoretical methods to support BAE Systems Integrated System Technologies validation of the structure, including:

• Conventional Vibration of sub-sections at TRaC's Warwick and Wimborne laboratories
• Modal testing at BAE Systems on the Isle of Wight, using an electrodynamic shaker suspended from a crane to drive the natural frequencies of the system.  TRaC engineers conducted Finite Element Analysis to prove the testing technique, de-risking the methodology in advance of carrying out the study. BAe engineers then compared the predicted modal results with those measured.
• Data was captured during the vibration testing and submitted to BAe Systems for qualification purposes.

The analyses was conducted in Nastran. The 3D model of the Raydome assembly was supplied by BAE Systems Integrated System Technologies. TRaC engineers extended the model to include the excitation system, repeating the analysis to replicate the test arrangement.

TRaC engineers have carried out a wide range of Modal test studies using alternative techniques.  In addition to conventional hammer testing, structures have been mounted on fixtures and excited by a conventional electromagnetic shaker or driven by a suspended shaker as in the case of the Sampson project.  Structures tested include a whole railway engine system in addition to a wide range of Aerospace and commercial products.

The customer needed our assistance to undertake the modal testing and TRaC's innovative approach was fundamental in solving the issues poised.  The contract worth in excess of 200K was awarded to TRaC.

A combination of Finite Element Modelling and Modal Testing was used to determine the local vibration environment of the Sampson Radar sub-assemblies that were deemed critical or significant by BAE Systems Integrated System Technologies. These sub-assemblies were then subjected to classical sinusoidal and random vibration qualification testing but to spectra modified, as a result of the Modelling and Modal Testing process.

The full Radar Array, a two-dimensional structure 3m x 3m was tested in a bespoke fixture, designed and manufactured by TRaC, which enabled the Array to be maintained in its in-service configuration whilst transmitting the vibration to the specified mounting locations.  The Array was tested using one of TRaC's two LDS 964 electrodynamic shakers and successfully demonstrated the integrated approach of combining modelling, experimental testing and qualification testing - all of which are carried out in-house by specialist engineers with extensive experience of these theoretical and practical disciplines.  

TRaC provides leading engineering services in static and dynamic structural analysis using Finite Element Analysis (FEA) techniques.  A typical stress analysis will involve finding accurate stress values either by hand calculations or FEA. Detailed fatigue assessments can be carried out to determine the components durability. TRaC can also perform physical testing of a component and correlate this back to the FEA model. This can be invaluable when developing a new component and understanding how it's performance will compare to the in-service component which has been physically tested. Our analysis team are able to apply their many years of experience in solving complex engineering problems to assist in the development of your products.

TRaC have expertise in the following market verticals:

Aerospace, Defence, General Engineering, Energy, Automotive, Rail, F1, Nuclear, Oil and Gas and Traffic Management