Body Structures Laboratory

Materials Development

We can develop materials and material models for safety applications, especially in load/deflection characteristic tuning for energy absorbing materials.

Impact Testing

FMVSS 201 "HITS" System

The MIRA "HITS" (Head Impact Test System) is a free flight headform launcher. The system allows impact tests to conform to FMVSS 201.

The featureless (noseless) head impactor is fitted with a tri-axial accelerometer. This is used to determine the head injuries sustained whilst impacting interior trim components. The launcher is very compact and highly adjustable. It can be used within a complete vehicle with minimal modifications (typically unbolting the doors is all that is required).

Trim Impact Simulation

Interior trim design can be optimised using MIRA's correlated headform model. Material characteristics and trim profiles can be modified to conform to FMVSS 201. These modifications can also be verified using the "HITS" rig facility.

Pendulum Impact Tests

Pendulum head impacts are used to evaluate the energy absorption characteristics of interior components and structures. The primary standard which calls for this type of impact is ECE Regulation 21. and derived legislation.

The impactor is swung around a pivot point (representing the occupants hip point). Accelerometer readings from the headform should not exceed 80G for more than 3ms.

The pendulum impactor system can also be used for other impact tests. Using alternative impactors, tests can be undertaken on "plastic" fuel tanks at low temperatures to demonstrate toughness.

Bumper testing to ECE R42 and US Federal, FMVSS tests for parking damag

In addition to testing against legislative approvals we regularly conduct these tests as part of benchmarking programmes or in the development of new bumper systems including correlation against CAE models.

Drop Rig Head Impact Tests (Linear Guided)

Linear guided head impacts are used to evaluate the energy absorption characteristics of steering systems.

Body Block Testing

Door System Impact and Intrusion Testing

MIRA can undertake the quasi-static door intrusion test to FMVSS 214. This test involves pushing a rigid half cylinder into the door above the sill height. The resistance that the door provides must meet certain load/deflection criteria.

The system can also be used to evaluate different door beam types in a very repeatable manner (although strain rate sensitivity must also be considered). Other side impact simulations can be undertaken on the stopping sled system. These small dynamic impacts can simulate cycle/motorcycles intruding into the structure. They can also be useful for side airbag sensor calibration work.

Side Impact (Vehicle Moving)

The increasing application of side airbags calls for new and realistic crash tests. MIRA has developed and successfully applied a new technique for propelling a vehicle laterally against any one of the MIRA selection of poles.

The test determines the effectiveness of head protection airbags, and is extremely useful for side airbag sensor calibration.

The sideways propulsion system is also useful for evaluating side airbag system sensitivity to kerb strikes. The system is much more repeatable and safer than the usual method of a driver trying to slide the car at a kerb on a test track.

Frontal Impact Tests

Frontal impacts are generally done in the internal test facility. Various barriers can be mounted to the 130 tonne main block or the Microcell array can be used. The entire block can be moved to one side on a cushion of air, to leave space for side, rear and car to car impacts.

Full frontal impacts can be undertaken, to ECE Reg 12, FMVSS208, ADR69 and similar tests. 30 degree angle tests (left or right hand) can be conducted with or without anti-slide devices. Low speed insurance repairability tests can use either the rigid offset barrier (European) or the angled barrier (USA). Accurate speed control and a wide range of barriers also allow almost any type of airbag calibration test.

Frontal Pole Impact Tests

Frontal pole impacts are important for identifying stiffness problem areas in vehicle front structures.

They are also very important for evaluating airbag sensor systems. Like underride tests, they often give later airbag fire times depending on the vehicle structure.

There are few recognised pole impact standards, but MIRA has a very wide range of sizes and types to suit almost any requirement.

Diameters available are:

180mm
255mm = 10"
200mm
220mm
360mm
330mm = 13"
355mm = 14"
432mm = 17"
177mm = 7" Short (IIHS Rear)

Underride Impact Tests

Underride impacts are generally undertaken in the internal test facility. The underride barrier can be adjusted in height to simulate the rear structure of almost any truck.

The construction of this barrier is very strong and particularly stiff vertically.

Underride tests are generally used as airbag sensor calibration tests. The front longitudinal structures pass beneath the barrier, giving high intrusion levels with a very soft crash pulse. The acceleration levels usually only reach airbag trigger levels when the engine is pushed back into the bulkhead. This causes a very late airbag fire condition.

Offset Impact Tests

Offset frontal impacts fall into 2 distinct groups. The MIRA facility is very well suited to undertake either types.

Offset Rigid Impacts

Rigid offset impacts are generally no longer used for injury assessment. However, the European insurance impact test calls for a 15km/h impact into a radiused barrier with 40% overlap.

Offset Deformable Impact

Offset deformable impacts (using an aluminium honeycomb impactor face) are now used for European legislative tests, EuroNCAP tests and American IIHS insurance tests. The very large Perspex covered pit, allows excellent high speed underside photography - vital for identifying structural deformation events.

Frontal Crashworthiness Simulation (Real World)

Although there is a basic requirement for compliance to legislative and the more demanding consumer tests, in most cases, even more demanding "in-house" standards are required. These "due-care" scenarios (pole impacts, dynamic roll-over, underrides, car to car impacts etc) are being analysed and developed for at vehicle concept.

The MIRA Microcell system is currently one of the few ways of gaining an insight into the "compatibility" of a vehicle design. CAE together with tools such as Microcell is becoming the main route to developing understanding in these areas.

Microcell

Microcell is a unique barrier load cell system developed by MIRA.

It allows load paths to be determined to an extremely high resolution - ideal for compatibility studies.

The data can be fed into a computer model as a boundary condition - for model correlation, or can be manipulated in a number of ways for easy visualisation.

Rollover Crash Tests

MIRA can undertake a number of different types of full vehicle rollover tests. These are normally undertaken on the HAVOC open air crash facility. Our current capabilities include:

FMVSS208 rollovers

We are currently expanding our range of capabilities to allow us to undertake "trip-over rolls" and "low roll rate rolls" (such as when dropping down an embankment). These tests are very important for curtain airbag sensor calibration.

MIRA has developed a rig to facilitate testing of systems to mitigate rollover ejection following guidelines and research conducted by National Highway Traffic Safety Administration (NHTSA) in the USA.

Rollover Ejection Mitigation

Commercial Vehicles

Cab Structure Testing

Many of our structural test facilities are designed with commercial vehicles in mind, so MIRA can undertake full cab structure development work to the very latest legislative and customer requirements.

Cab Load Simulation Push Testing

The MIRA truck cab push rig applies load to the back of a truck cab to simulate load movement during a violent stop.

Loads of up to Z kN can be applied in accordance with ECE Regulation 999.

The support frame bolts to the top of the vehicle chassis to provide a reaction load path. Load and deflection data is then recorded to show how the structure of the cab behaves.

Cab Roof Integrity Testing

The MIRA truck cab roof crush rig is effectively a large hydraulic press. Loads of up to Z kN can be applied in accordance with ECE Regulation 999, and cabs of different heights can be accommodated.

Load and deflection data is recorded to show how the structure of the roof behaves.

Load and deflection data can be recorded to show how the structure of the roof behaves under pressure.

ECE Reg.66 Bus Rollover Tests

MIRA can undertake the static rollover test as described in ECE Regulation 66. This test is intended to prove the structural integrity of the roof structure of buses and coaches

Compatibility - Real World Vehicle-to-Vehicle Impacts

Structural Aspects

The subject of compatibility is one of the major issues facing the automotive industry.

Compatibility is the study of how vehicles transfer load and deform when they impact each other. The main problems occur when the structural members of one do not align with the structural members of the other.

Injury Aspects

Compatibility is not only a structural issue. The misalignment of structural members can cause very late airbag firing times in frontal impacts.

When designing "compatible" vehicle fronts, the effects on pedestrian safety should not be overlooked.

In side impacts, additional injury risk can be caused by some front structure features, such as bull bars.

MIRA is currently undertaking research in the area of compatibility.

Car-To-Car Impacts (Both Vehicles Moving)

MIRA can undertake moving car to car impacts in either the internal crash laboratory or outside on the HAVOC facility.

Tests in the main crash laboratory have the advantages of being independent of weather with good temperature control, excellent speed control and underside high speed photography. Test speeds of up to 35mph for each vehicle up to 2.5 tonnes are possible, with any amount of overlap.

Tests on the HAVOC facility can be undertaken at higher speeds with heavier vehicles. It is also very useful to have large amounts of open run off space when the departure directions cannot be accurately predicted.

Occupant Protection

MIRA has wide experience of modeling vehicle occupants and their protection during impacts.

Some of the benefits of using occupant simulation are:

• A wide variety of occupant sizes and positions can be assessed at low cost
• A range of impact types and speeds can be assessed
• Effects of specific component changes can be determined quickly
• The effects of different intrusions and acceleration can be determined

Working together, MIRA occupant analysts, structural analysts and integration engineers provide customers with highly effective solutions.

CAE Modeling

FMVSS 208 Developments

MIRA is well equipped to develop restraint systems which meet the demanding new Federal requirements.

New tests have been implemented using 5th percentile Female Hybrid III dummies to test restraint system performance for this high risk population group. The new tests for 5th Percentile female include 30mph belted and unbelted tests and a 25mph 40% overlap offset deformable impact test.

New Out Of Position (OOP) tests also assess the risks to vulnerable occupants. 1 year, 3 year, 6 year and 5th percentile female dummies are checked for static deployment suppression and low risk deployments.

Occupant Restraint System Simulation

When designing or optimising a restraint system, there are very many variables which can affect the performance of that restraint system.

The physical effects of the components must be understood. These can predicted using computer models or tested directly if parts are available.

The component characteristics are then combined into the system model, which is used to consider combinations of variables.

It is not practical to test or even model the many hundreds or even thousands of permutations of variables.

Hence MIRA uses a recognised technique known as "Design of Experiments" (DOE).

The DOE process is used to identify the most influential system variables from a large number of variables. This in turn determines the combinations of variables which are modeled, sled tested and crash tested.

Frontal Airbag System Simulation

MIRA Crashworthiness and Impact Analysis assist or lead the development of airbag systems by evaluating the effects of different parameters on injury levels.

These parameters include:

• Bag Size
• Fold Pattern
• Vent Sizes/Material Porosity
• Inflator Performance

Different sized occupants, occupant positions and impact types can be modeled, as can the effects of high and low temperature (gas generators change performance with temperature).

Front Airbag & Seat Belt Development

Frontal occupant restraint system development is one of the main activities for the HyGe facility. The ability to be able to "tune" the crash pulse to suit a particular vehicle and impact type is very important. The system is very repeatable and cost effective, as the vehicle body is not damaged from test-to-test.

Typically, only the seats, belt and airbags are changed between tests. The small number of variables means that effects from changes in design level of the test components are much clearer than in a series of crash tests.

Seat Belt Anchorage Test Rig

MIRA's seat belt anchorage rig is the most sophisticated of its kind. Capable of loading the seats under test in only 100ms the rig has a capacity of 30 Tonnes it has a quadruple ramping system making it ideal for testing coach and minibus seat belt anchorages.

Airbag Development (Static Deployment)

MIRA can undertake static airbag deployment work for system development, conformance checks or can use the facility to determine occupant location risks for "smart" systems.

• Typical tests which can be undertaken are:
• High Temperature - Airbag most aggressive
• Low Temperature - Airbag least effective
• Different Occupant Positions - Compare "OOP" risk levels
• Child Seat Risks - Determine which configurations are acceptable

All tests can be instrumented and filmed at high speed. This is particularly useful for determining tear seam performance for seat mounted side airbags, for example.

Airbag Calibration Services

Airbag calibration is a complex balance of a number of different requirements.

MIRA has considerable experience in optimising sensor system for customers. In very simple terms, the main requirements are:

• Must Fire Threshold - The levels of impact above which the airbag is deployed.
• Must Fire Time - The instant at which the airbag fires relative to the start of the impact.
• No Fire Threshold - The level of impact below which the airbag is definitely not deployed.
• Abuse Conditions - The possible events that may be misinterpreted as impacts.
• Out Of Position - Suppressing deployment when occupants are in hazardous locations.

The experience of MIRA engineers can assist in whatever type of calibration you need - from a simple frontal pretensioner fire to a smart side curtain bag.

Safety Integration

What is Safety Integration?

Safety Integration is the activity which pulls together all aspects of passive vehicle safety and makes those aspects work in the optimum fashion.

Why is it necessary?

It is most important for someone within the development process to have a good grounding in all the areas, or else inappropriate solutions could be developed.

For example:

A frontal airbag system does not deploy fast enough. Do you:

• Use a more aggressive inflator?
• Reduce the thickness of the module tear seam?
• Change the airbag sensor calibration parameters?
• Increase the bumper crush can stiffness to give a sharper crash pulse?

Any or all of these may be the solution, but the safety integration engineer understands the likely magnitudes of each, understands the knock-on effects and understands the costs.

A MIRA Safety Integration Engineer can advise the development team on the optimum solution.