Trauma Pads for Hard or Soft Armor - Necessity?
There is little info on the real purpose and proper application of "trauma pads" or similar trauma reducing inserts designed as appliques to soft or hard armor systems, though the concept has existed for decades.
Generally speaking trauma inserts made for soft armor go in front of the main soft armor package and are typically situated in the center chest area, roughly over where the heart of the wearer should be. These are made from ballistic materials such as Kevlar or UHMWPE and can come in soft or hard forms. Trauma inserts for hard armor are typically soft pads composed of high density foam, soft ballistic material such as Kevlar, or a combination of the two. These are always placed behind the armor plate.
The general idea of such trauma pads or hard trauma plates is to reduce blunt force trauma generated by a projectile strike to the wearers armor. Some are designed to offer increased "special threat" projection from certain threats that a typical soft armor vest may not stop on its own. This is the case with the ATT Tactical insert pictured above, right.
Trauma inserts for soft armor vests typically only offer coverage up to 6"x8", with other common sizes including 6"x6" and 5"x7". They are mostly meant to reduce blunt trauma over vital areas such as the heart, with the idea being they improve survival rates or at least lessen the injuries received in those areas. This all assumes the projectile strikes the trauma insert of course.
However their level of necessity is questionable. Some soft armor carriers are not designed to accept any trauma inserts. Aside from that soft armor made to meet NIJ standards is meant to be stand alone, that is to say a hit over a vital area should not be fatal or even result in particularly serious injury assuming the striking projectile was within the armors range of rated threats. Real world shooting events in which wearers have been struck in the chest, even multiple times, with no trauma inserts over their base soft armor package typically result in positive outcomes for the armor wearer.
In regards to the soft trauma pads designed to be worn behind rifle rated armor their efficacy is somewhat debatable and their actual utility even more so. While they may reduce blunt force trauma from a hit to the armor they will not offer increased ballistic protection from threats that may penetrate the armor (at least in the case of non-ballistic backers) nor are they a necessity at all. Aside from that they will of course increase the weight and bulk of your armor system.
Stand alone rifle plates (which the vast majority of rifle plates on the market are) are designed to work without any supporting soft armor or trauma pads. Whether the armor is ceramic, UHMWPE, or metallic based (steel, titanium) trauma pads or supporting soft armor are not needed assuming the plates are stand alone.
With all that said I'm of the opinion that the very concept of the trauma insert for stand alone armor systems was created by the armor industry largely as a way to sell more product. They are, in my opinion, a product that serves primarily to get buyers to spend more money and increase the overall weight/bulk of their armor with little meaningful gain. However there is no measurable downside to their use other than the aforementioned increase in cost and minor increase in weight/bulk.
That said if you feel more comfortable with using trauma inserts in your armor system and find the minor downsides acceptable then by all means do so, but know that they are not a necessary part of a stand alone armor system.