The linear impactor was originally designed to simulate head-to-head collision between two NFL football players as a means of evaluating helmet effectiveness. While helmet tests are traditionally done using drop towers, the extreme closing speeds of player-to-player hits makes a drop test not feasible. The helmet being evaluated is positioned on the test headform, typically a Hybrid III automotive head and neck, instrumented to record linear and angular head acceleration as well as upper neck forces and torques.

The machine is charged with a pre-determined set pressure to achieve a desired speed and the impact ram is propelled into the helmeted headform. The advantage of this system is that the headform is free to deflect and rebound in a natural way to study complete head kinematics.

This system has been demonstrated to be both repeatable and reliable and is adaptable to other situations where bodily impacts are desired in the 5-13 m/s range. The impacting face may be replaced with other rigid or semi-rigid surfaces to simulate a broad range of impact conditions. The headform may be replaced with other parts of a test mannequin or perhaps a dedicated torso membrane. At Biokinetics we have used this machine to evaluate everything from football helmets to passenger bus window glazing in rollover situations.

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Mouthguards may protect your teeth, but what about your brain? To investigate the protective aspects of mouth guards in relation to concussion, a headform with an articulating mandible has been developed. Based on the 50th percentile Hybrid III manikin skull, the new headform has a steel mandible with a steel upper and lower dentition and compliant temporomandibular joints (TMJ).

The TMJ provides a biofidelic range of motion to allow for the insertion of mouth guards. Mandible force-displacement response has been validated under direct chin impact against cadaver performance corridors recently developed at Wayne State University. The headform was developed in conjunction with the National Football League to assess the capacity of mouth guards to reduce concussion risk among helmeted players. However it may also be used for military and automotive research of mandible, TMJ and dentition injury.

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The Ballistic Load Sensing Headform (BLSH) was originally developed to evaluate ballistic behind armour effects but can also assess blunt force trauma from a host of generalized head strikes (i.e. falls, vehicle interactions, less-lethal weapons). Injury risk prediction is based on the comparison of skull loading to human fracture tolerance.

 

The BLSH has an array of seven load sensors located behind the ballistic strike location. During the impact event, shell deformation that bears any load on the headform is recorded by the sensors. Optional headform models are available for front-rear, left?right and crown locations.The V50 of a helmet is first established with a penetration headform which offers proper helmet support and standoff as well as jaw and nape features for attachment of the retention system. The units are economical and suitable for multiple perforations before disposal.

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Blunt force impacts in the military environment can occur from multiple sources including airborne objects such as those ejected from IED blast, striking objects in a vehicle crash or simply falling to the ground. Automotive-style test dummies can measure distributed forces at low impact speeds. But what about for localized forces at high impact speeds such as from small projectiles, less lethal weapons or even behind armour effects?

The Blunt Trauma Torso Rig (BTTR) was developed to mimic the human chest response under moderate to high rate impacts with small projected areas. Blunt trauma is assessed by measuring the localized dynamic deformation and loading area and correlating this to injury thresholds derived from biomechanical studies.

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Biokinetics' helmet impact tower (HIT) is used to evaluate the impact performance of helmets across a range of test conditions specified in standards such as the ASTM, CPSC, DoT, ECE and Snell. The self-supporting tower consists of a pedestal, linear bearing rail, lift carriage, drop carriage and lift motor. The drop carriage supports the locking ballarm and headform and is automatically raised to the user-defined height where upon command the helmet is released in guided free-fall onto one of many steel anvils. The forces transmitted to the headform are measured with an accelerometer located at the head's centre of gravity.

A full compliment of impact headforms, data acquisition and measurement systems is provided. Testing is streamlined and data reporting is greatly simplified with the integrated Helmet Test Software (HTS) and electro-mechanical systems.

The drop tower complies with many helmet test standards and it can be customized the client's exact needs.

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The fore-aft and lateral crush resistance of a ballistic helmet shell or facial protector is described in several military helmet specifications. The Helmet Fatigue Tester (HFT) assesses the structural rigidity of a helmet or helmet component in any direction. It works by squeezing the helmet between two platens where the compression rate, measured force and number of compression cycles is computer programmed. The HFT has a peak compressive force of 4450 N (1000 lbf) and a maximum stroke length of 55 cm (22 in).

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