Since the founding of the company in 1971, Frazer-Nash Consultancy has been at the forefront of the development and application of computerised simulation techniques. Frazer-Nash has considerable simulation experience which ranges from the analysis of vehicle crashworthiness and the examination of rotary machinery performance to the simulation of human injury mechanisms.
Our simulation technologies and skills cover a wide range of areas:
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Accident Investigation
Our simulation skills are often called upon as part of an accident investigation, either to recreate the incident, and hence provide evidence with regard to the cause or subsequent damage mechanisms, or to understand how design changes could mitigate the consequence of future similar incidents. Technologies that can be utilised in such investigations include:
- Examination of vehicle kinematics prior to and during the event, e.g. the motion of a petroleum tanker leading to a roll-over
- Simulation of the structural response (crashworthiness) of the vehicle or structure
- Prediction of the pressures generated in a blast event
- Examination of the injury mechanisms to people involved in the incident
Frazer-Nash has provided expert witness testimony in a number of litigation cases and a number of our staff are accredited for this purpose.
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Blast Propagation and Structural Response
Frazer-Nash has many years' experience of the simulation of explosive and other blast events. Our capabilities include the simulation of the blast wave propagation, both in air and water, together with the prediction of the response of structures and injury to people.
Recently conducted projects include:
- Examination of rarefaction waves generated by a pipe failure
- Prediction of the charge size required to demolish a masonry building
- Assessment of the response of offshore blast panels due to a gas explosion
- Evaluation of damage to an oil supertanker as part of a litigation case
- Examination of the integrity of equipment attached to submarines
Blast wave propagation studies are conducted using a number of tools, depending on the particular application. For water-borne shock, DYNA3D is used. For air-borne shock, tools which can be applied include: FLUENT CFD analysis, SALE or other software as appropriate. Structural response modelling is normally conducted using DYNA3D. However, for simpler structures, GENDYN models can be used effectively.
Crashworthiness
Frazer-Nash designs crashworthy structures for land, sea and air vehicles. We offer a range of services which encompass the complete design process from concept through to prototype test and full production. The key design aims are the same for all applications and relate to ensuring controlled collapse of the exterior whilst maintaining safe passenger spaces.
We make extensive use of the DYNA3D and ABAQUS finite element codes in the design process. These computer based techniques facilitate the rapid development of designs at a minimum cost to the client.
Frazer-Nash is prominent in the rail industry and has designed the crashworthy cab and non-cab ends for most of the crashworthy trains on UK railway lines. The recent successful demonstration of the crashworthiness of the Heathrow Express rolling stock represents the latest achievement in this area for Frazer-Nash Consultancy. The design and structural simulation work was undertaken for Construcciones y Auxiliar de Ferrocarriles (CAF) of Spain and was completed in rapid time, without the need for development testing.
Other areas where Frazer-Nash has applied its structural design and analysis expertise include:
- Bird strike on aircraft
- Blast proof vehicles
- Ditching of helicopters
- Rollover of petroleum road vehicles
- Launching of freefall lifeboats
- Structural response to blast
Human Injury
For over twelve years, Frazer-Nash has been working in the field of human injury biomechanics. Much of this work has been for the Defence Evaluation and Research Agency (DERA) and has involved the use of computer models to develop a detailed understanding of the mechanisms of human injury and methods of providing protection. We have also developed a number of mechanical surrogates which replicate the response of sections of the human body to impact and blast.
There are two simulation techniques used in our human injury work:
DYNAMAN
Is a finite element model of a human based on the DYNA3D code. Any size of adult or child can be modelled and the anatomical joints can be assigned any characteristic. Hence the model can represent the various levels of human attentiveness and strength, such as a fully braced or unconscious person. Previous applications of DYNAMAN have included models of:
- Vehicle occupants in crash event
- Human response to blast
- Passenger response on escalators during emergency braking
- The response of wearers of lifejackets during self-righting.
Clients for DYNAMAN work have included: rail operators, The Railways Inspectorate, DERA and the Health and Safety Executive.
Detailed Body Part Models
These are used to examine the actual mechanisms of injury within the body. Sections of the body including the internal organs are modelled explicitly, using the finite element code DYNA3D, and appropriate loads are then applied. The stresses and pressures generated within the body can then be examined and correlated with observed injuries. These models are used to develop a full understanding of how injuries occur and hence how to protect against them. Mechanical surrogates have also been designed using the simulation work to assess the performance of various concepts. Typical projects include:
- Development of a rig to simulate thoracic response to impact
- Examination of the mechanisms of traumatic amputation of limbs
- Investigation into the mechanisms of lung injury in blast and impact
One further area of human injury work in which we are involved is probabilistic approaches. Typically such approaches are risk based and used in support of safety assessments of plant or equipment.
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Interaction of Structures with Water
Frazer-Nash has developed two techniques for examining the interaction of structures with water:
- The first technique comprises an explicit model of the water using fluid material models within finite element codes such as DYNA3D. This technique is suitable when there is minimal relative movement between the structure and water, but has a number of limitations to its accuracy and applications.
- The second technique uses a development of the DYNA3D finite element code produced in-house that allows the complex water interaction forces to be modelled using a series of complex pressure loads. All the forces generated by the interaction of water and a structure are included in new algorithms that have been added to the code, namely: buoyancy, drag (including cavitation effects), wave slap (impact forces) and added mass effects. This new technique, called HydroDYNA, has been validated for a number of applications including lifejacket self-righting performance, free-fall lifeboat launch and RNLI lifeboat motion through water and in drop tests.
If you would like further information about our services or products, or want to know if we can assist you in a particular project, please complete the form on the Contact Us page.