Advanced computer programming, combined with materials developed specifically for military defense applications, is leading the way toward the development of the next generation of body armor for law enforcement officers.

Commissioned by Scotland Yard, the United Kingdom's Defence Evaluation and Research Agency (DERA), based in Farnborough, Hampshire, is using computer technologies to study human stabbing actions on synthetic skin material. The combination of technologies is designed to mimic the reaction of the human body to a deadly assault and record those effects in the search for an efficient and effective armor for police officers.

The new research, which is expected to lead to substantially higher levels of protection against the effects of blunt trauma, as well as knife and gunshot penetration, has for the first time, provided detailed scientific information on the levels of threat posed.

Using recently developed synthetic human tissue materials, defense scientists have built a lifelike dummy capable of reacting to body blows in the same way as the real victims of assault. Meanwhile, other scientists, also based at DERA, have designed equipment that, with the help of computer analysis, simulates knife attacks in "virtual reality," as a first step in understanding this extremely complicated threat.

Problematic Knife Attacks

Knife attacks, unlike other forms of assault, present a wide range of difficulties, including the sharpness and width of the blade, the force applied, the direction of travel and the weight behind the initial thrust, all of which will vary from one attack to another. With every blow to the body, shock waves are set up which, whether or not the knife penetrates  the armor, are potentially fatal. The recognition of these difficulties, coupled with the concern of senior police officers and others about what they see as the inadequacies of the current test methods for body armor, has led to the present request for the military's help.

"Body armor in the United Kingdom is, at the moment, tested by having a weighted knife dropped on it, fired at it or swung at it on the end of a metal arm," said a source within the industry who preferred not to be named. "The problem is that none of these test comes close to replicating real life. Nor can they tell us anything about the absorption properties needed in a vest to protect human against the potentially fatal effects of blunt trauma."

This somewhat pessimistic view is not, however, universally held. There are some, like Dr. Mike Taylor, Director of Technology Development at Scotland Yard, who believe that these methods can provide a valid starting point in body armor testing from which further progress can be made. Within this view, technology convergence is now making it possible to develop new testing procedures at the same time that new lightweight substances, originally conceived for the defense market, are being produced.

"From my previous work in the area of defense I was aware of DERA's research program and of the new composite laminates that were evolving for use in the aerospace industry," said Taylor. "It occurred to me that many of the properties exhibited by the new materials were exactly what we were looking for in our body armor.

"What (London) police officers now have in the way of protection is the very best that is currently available but it can be improved by the use of advanced materials and advanced testing procedures. And this is exactly why we have approached the military for help."

The Threat Defined

But before assistance could be given, the scientist had to understand the parameters of the threat being faced by officers on the street. Research in America and elsewhere has tended to concentrate on the levels of threat posed by ballistics, particularly those faced by soldiers on the field of battle. Little or no data was available to assess attacks by a pointed instrument, while still less was known about the blunt trauma effect on the human body, resulting from a high impact blow.

Simply providing an armor that prevented penetration by a pointed instrument or bullet or explosive charge would not deal with the effect of the shock waves caused by the striking force of an object. Blunt trauma was and continues to be the cause of grave concern.

"Just firing a bullet or swinging a knife at a piece of armor and seeing whether it has penetrated or not, does not prove the effectiveness of the armor," said a DERA research scientist. "Even if the projectile does not penetrate, the effect of the blunt trauma might still kill or injure the victim."


Therefore, as a first step, a team now led by DERA's Graham Meeks, produced a knife handle, crammed with electronic sensors and capable of accepting a range of blades. This was then linked to a computer before being given to a large number of volunteers, who were invited to stab a target dummy designed to recoil as much like a human as possible. Each stabbing action was digitally recorded for its degree of force, velocity and direction.

"In the initial stages we wanted to produce a force/ velocity curve to understand the impact event," said Graham Meeks. "But there was little to be gained from stabbing an object that did not respond as a human would do. Stabbing actions alter according to the resistance offered. A person stabbing a piece of solid wood acts differently than one stabbing a piece of plasticine or another human being and it was therefore important that we created, as closely as possible, the same conditions for the tests as would be met in real life."

The absence of high-tech instrumentation and materials able to respond to the threat in the same way as human skin and tissue has meant that it has not, until recently, been possible to accurately measure the physical effects on the human body of an impact- at least until after the event. Major advances, closely based on military-defense-related technology, have not produced the skin and tissue simulates, making a substantial difference to the research into a better level of body projection.

"In a sense, the origin of the trauma is unimportant," said Dr. Sandy Bell, the leader of the team looking at the effects of blunt trauma. "The shock waves set up by an explosive charge are generically similar to those set up by a knife or a bullet striking the body armor."

"What we have found is that some types of body armor actually make the trauma effect worse and it is important that we understand how much the human body is capable of withstanding."

Computer Assistance Critical

But it was still necessary to know the exact form and distribution of the energy (or shock wave) and it was the third of the recent advances that has made this possible. Computer- based analytical methods now allow snapshots of the effect that a blow is having on the human dummy. In the split- second of time being covered, the analysis shows the distribution and form of the shock waves and the effect that, at each moment in time, the trauma is having on the "body."

It will, according to Scotland Yard's Dr. Taylor, be another year, at least, before the results of the present research begin to bear fruit. The level of technical knowledge is not yet advanced enough to convert the latest, manmade, laminates into a form capable of creating a woven material. Even when it is possible, it will still be necessary to achieve the correct geometry in the weave that retains and preferably enhances the existing properties of the substances. He and the DERA scientists, however, remain optimistic that, in the fullness of time, a way will be found to build armor that will offer substantial improvements in the level of protection of officers.

Looking to the Future

There is little doubt that improvements are necessary and overdue. Research in the United States and in the U.K. show that officers will not wear body armor if it was too hot, too heavy, restricts movement or cannot be concealed. Perhaps because of this, current body armor tends to be issued on the basis of the threat being faced. Officers dealing with an armed situation will, for short periods, wear armor that would be wholly unsuitable for routine patrol work. On the other hand, the search for comfort has inevitably reduced the level of protection offered to the officer on the street.

There is no question that the existing American NIJ standard of a 44 mm "backface deformity" for ballistic protection, i.e. the depth of the dent caused by the bullet hitting the armor, has saved a great number of lives in the states but complaints about wearability continue and there is mounting medical evidence of the substantial, if nonfatal, risks inherent in the blunt trauma effect occasioned by a 44 mm backface deformity.

With growing levels of violence being faced by officers the world over, society owes them an obligation to produce the best protection of which technology is capable. The DERA research is a valuable contribution to this effort.

Patrick Hook retired in 1994 after a varied and distinguished 31-year career with the Metropolitan Police in London, rising to the rank of chief inspector. His last four years of law enforcement service were spent at the famed Scotland Yard where he was involved in planning and developing policy on a wide range of issues. Hook, who resides in England, is a prolific freelance writer in Europe often on police matters. This is his first contribution to POLICE.