Defence

Vibration

Within the defence industry, the effect of vibration on components, systems, modules and complete structures is a major area of concern.

Based on our PULSE data acquisition system, our solutions include conventional vibration measurement, modal analysis and operation modal analysis.

With military vehicles the effects of shock and pyroshock have great influence on suitability for the designed function and on durability under hazardous and harsh conditions. PULSE is the ideal test platform for vibration testing on a wide range of vehicles, from motorcycles to tanks and armoured personnel carriers. For example, when installing vulnerable electronic equipment, it is vital to choose a location within the vehicle that is least affected by pyroshock And vibration test data is essential when compiling requirement specifications in purchase contracts.

> Case Study: Royal Neherlands Army
> Article: Developing I-deas
> See solutions for structural analysis

Acoustics

Brüel & Kjær’s modular and scaleable PULSE data acquisition platform together with a large range of software, is ideal for general noise and vibration testing within the aerospace and defence industries. Solutions can be provided from two up to hundreds of dynamic channels, with a variety of front-end modules depending on your application and bandwidth needs.

PULSE also finds itself in some unusual situations.  Terma A/S is a leading defence contractor in Denmark and specialises in the development and production of systems for Electronic Warfare Integration and Control, Tactical Reconnaissance and Environmental Surveillance.  Terma is involved in designing the next generation of pilot helmets, also referred to as Joint Helmet Mounted Cuing Systems, including 3D-Audio.
 
> Case Study: Terma
> Article: Noise Mapping of Military Vehicles
> See solutions for acoustic analysis

Shakers and Controllers

Brüel & Kjær can supply an extensive range of vibration exciters and digital closed-loop shaker controllers using the latest advanced technology.

The Royal Institute of Technology in Stockholm and Karolinska Institutet, one Europe’s largest centres for medical training and research, are together engaged in the study of vibration on military helicopter pilots. The test setup consists of a pilot’s seat and dummy flight controls mounted on a frame that is excited by a large shaker. The shaker is driven either by a swept sine wave from 2½ Hz to 30 Hz or by prerecorded field data.

> Article: Is your Random Vibration Testing Fulfilling MIL-STD-1540D?
> Article: Kurtosion® – Getting the Peaks back into your Product
> See solutions for vibration testing

Engine Maintenance

Vibration Check Systems for Jet and Turboprop Engines.
To ensure the safe operation and to optimise the uptime of fighters and transport aircraft, Brüel & Kjær provides systems for field-testing of specific engines based on PULSE. Typically, vibration measurements are made on the first order of the gas turbine generator and the free turbine (in case of turboprop configuration) according to the procedures specified by the engine manufacturers.

A simple user interface leads the technician from the identification of the engine, to the monitoring of the signals and comparison with threshold levels (for confirmation measurement). The user interface also helps the technician to store the signal in a database and to produce a service report where the results are clearly indicated as "go" or "no go". The report can be sent directly to the engine manufacturer along with the results for further analysis. It is also possible to have diagnostics software installed (this software is often referred to as the "expert system") to guide technicians in identifying problems faster.

The systems are available as field test systems (installed in weather and shockproof carrying cases) or for permanent test cell installations.

> Data sheet for PULSE Vibration Check System for Aircraft Engines
> Picture: Field test system in action
> Picture: Laptop in carrying case
> Picture: Carrying case 2

Modal Analysis

Both conventional modal analysis techniques and operational modal analysis (OMA) are widely used in the defence industry. Typically, modal testing applications are used to investigate the effects of vibration on complete structures and components. Testing is carried out during the R&D phase to ensure durability, to investigate fatigue, and measure local environment parameters. Modal analysis enables mathematical modelling programmes to be accurately verified.

The control, monitoring and analysis of modal testing frequently includes many parameters such as force, acceleration, strain and stress, voltages, temperatures and pressures. With its provision for recording DC inputs, and support for several hundred dynamic measurement channels, PULSE is ideal for your modal analysis needs.

> Case Study: Kongsberg Defence & Aerospace
> See solutions for structural analysis
> Learn more about the PULSE platform
> Operational Modal Analysis in the PULSE Catalogue
> Product Data: Structural Dynamics Test Consultants

Underwater Acoustic Ranging

The purpose of acoustic ranging, both static and dynamic, is to measure the noise generated by surface vessels and submarines at various speeds and when stationary.  A vessels acoustic signature is most important for its function in military operations – not only so that an individual vessel cannot be identified, but to ensure that vessels in the same class all have the same noise parameters.

Acoustic ranging is performed, for example, after major maintenance work, modifications or the installation of new equipment in order to reveal any changes in the noise levels of the vessel. New vessels are also measured to ensure that noise levels comply with the building specifications and NATO requirements.

Brüel & Kjær has a range of hydrophones, some of which are suitable for use at a depth of 1000 metres. Combined with our PULSE data acquisition system, we have an underwater noise measurement solution that is used throughout the world.

> Case Study: Royal Norwegian Navy
> Article: Maintaining Acoustic Stealth
> See our range of hydrophones
> Learn more about the PULSE Platform