Test Standards

The most commonly used and most comprehensive test standards are those published by the United States National Institute of Justice (NIJ). These were developed to provide police forces with a uniform standard against which to have body armour tested. Other organizations as a matter of course now use these standards for their own purposes.

The North Atlantic Treaty Organization (NATO) has developed its own standards which are commonly known by the acronym STANAG. Australia and New Zealand have developed some standards as well, which are referred to as AS/NZS. The United Kingdom Police Scientific Development Branch (PSDB) researched stab attacks and developed a standard and test regime which are now used worldwide and have been adopted as part of the NIJ Standard.

It is not unusual for users to develop a specific test requirement for a material based on its intended use. The Australian Ballistic Laboratory (ABL) is able to design and implement such test regimes on request. The accompanying photographs show the indoor range viewed from the rear and a view of the operator preparing to remotely fire a test.

Strike Plates

Users who purchase any armour, but particularly body armour, need to be assured that it will perform in the manner claimed by the manufacturer. As was explained above, numerous test standards have been developed to meet the needs of particular countries or groups. Some tests have been developed for particular applications such as stab protection.

Perhaps the most common form of testing is of strike plates; the hard armour inserts for body armour. These are generally tested to the United States NIJ Standard, although other standards are also used. The accompanying photographs show two strike plates which have been tested.

Back face Deformation

When body armour is struck by a projectile which does not penetrate, the rear surface of the armour will deform. This process is sometimes referred to as mushrooming. It is possible that this deformation can cause injury to the wearer even if the projectile has not penetrated the armour. This type of injury is called blunt trauma and can cause minor injuries such as bruising to more serious injuries where major organs are damaged. The National Institute of Justice Standard allows for a maximum deformation to a depth of 44mm.

Armour is tested using what is called a backing material. In this case it is made from plasticine, which will record the actual deformation which occurs. After testing, the depth of penetration is measured to determine whether the armour meets the NIJ standard. The accompanying photograph shows the Backface Deformation being measured, while the other shows the effect on a variety of bullets which have failed to penetrate a target.

Helmet Tests

Helmet technology has moved forward dramatically in recent years. The development of the United States Army helmet as a result of the Personal Armor Systems Ground Troops study was in the forefront of this process. Techniques which had been used in the development of fibre based body armour were applied to the construction of helmets for combat, riot situations and for recreation purposes.

This has necessitated the development of specific testing procedures for helmets. The most common is known as the V50 Test which identifies the velocity at which a projectile has a 50% chance of penetrating. The accompanying photographs show a helmet mounted in a special jig ready for testing. The second photograph shows the projectile and sabot used in the V50 Test.

Structural Tests

This area of testing covers a wide range of materials and applications. The materials can be steel, glass or fibre based armour in both soft and hard forms. The latter can be composites or are hard as a result of the manufacturing process. These materials can be used to protect buildings, to construct target ranges, in the protection of boats, aircraft and vehicles and many other applications.

Materials are tested against the conventional standards but clients often ask for specific test regimes to suit the purpose for which the armour will be used. Recently the laboratory was asked to test a sample to destruction to determine its lifespan in its planned use. ABL can develop specific tests to meet a clients needs. The adjoining photographs show ballistic glass and steel, which have been tested.

Stab Tests

Over recent years, the demand for some form of protection against stab attack has increased dramatically. Until a few years ago, the only forms of defence against this type of attack had changed little since the Middle Ages. The basic protection was provided by chain mail covered in a tough material such as leather. Even after the introduction of the 'miracle' ballistic fibres, it was still necessary to include some metal in the composite armour mix. Recent advances have now eliminated this requirement.

The most convincing research into stab attacks was conducted in the United Kingdom at the Police Scientific Development Branch. After some years PSDB developed standards for stab resistant body armour and a corresponding test regime. The accompanying photographs show the approved test rig being operated by the Manager, Proof and Testing. They also show the test blade about to impact on a stab resistant vest, which is being tested for certification.