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Product Design: The Hard Case for Soft, Flexible Impact Protective Gear in Sports

Posted by Dave Sherman on Tuesday, September 8th, 2015 | No Comments »

By Dave Sherman, Technical Design Solutions Manager, XRD® Impact Institute

A couple of small knee pads?

A couple of small knee pads?

More than 65 million years ago, an epic struggle for the World Championship played out. On the one side, the Dinosaurs were the defending champions with a style that tended to be bulky and slow; they relied on heavy, hard shell armor to keep them safe. On the other side were the Mammals, challengers with a new style that replaced bulky armor with agility and speed. The results would change world dominance forever.

Today, there’s a similar, though less epic, change playing out in the nearest Dick’s Sporting Goods and other stores in the big box sports retail jungle. Athletes are choosing between:

Bulky, inflexible, hard-shell protective gear


Lower profile, moves-with-your-body, soft protective gear

To many people searching the aisles in big box stores, the choice seems clear: the bigger and more rigid a shin or shoulder pad, the better it will protect. We would like to challenge this assumption by providing you with more facts and data about protective equipment designs.

The truth is, bigger and more rigid protection tends to limit your performance and your overall enjoyment of the sport.

Testing Design Assumptions

Buster – one of the impact testers at the XRD Impact Institute.

Buster – one of the impact testers at the XRD Impact Institute.

First – let’s look at the data…

We went to the XRD® Impact Institute and designed an impact simulation that tested both hard shell and soft protective pad options. The impact test consisted of:

  • Mocking up various protective pad options
    • 5 hard shell materials with a range of stiffness, laminated to 3 soft foam materials, with different impact properties
    • 3 soft foam materials with no shell
    • 18 total samples were tested
  • Choosing an impact scenario
    • Dropping a 4 pound weight from 3 feet on each protective pads
  • Recording the results
    • Measuring the transmitted force through each protective pad sample
    • The lower the transmitted force, the lower the amount of impact felt by the wearer

The impact is equivalent to 16 Joules, which is an average sports impact. It’s akin to getting hit by a small stone while riding your bike.

Various impact protection foam samples used in testing.

Various impact protection foam samples used in testing.

The Value of Flexibility

Now let’s consider the value of flexibility. From an athlete’s perspective, soft and flexible gear delivers many performance benefits, such as:

  • More customized fit
  • Fewer hotspots against the skin
  • Gear that moves with you
  • Ensures more reliable and uniform protection

There are many ways a designer can achieve “flex” within a product, but one method is to start with soft, flexible component materials.

To determine flexibility in our test, we used a visual assessment of each protective pad combination and ranked them in order of stiffness. The materials ranked:

Screen Shot 2015-09-08 at 12.17.14 PM

Visual representation of shell material flexibility

Visual representation of shell material flexibility.

This image to the right demonstrates the flexibility of the shell materials with steel on top, foam-only at the bottom.

For foam, we chose materials that would give us a range of impact results. We chose an EVA foam that is commonly found in combination with hard shell materials in protective gear, and we chose two densities of XRD® materials.

The Results

Yes, 3mm steel sheets can offer good protection, but we’ve moved passed the days of knights in shining armor. Plus, the weight factor is a big disadvantage.

The data shows that a stiffer shell can make a poor impact absorbing foam, such as EVA, perform better. BUT the results are not significantly better than using ONLY a flexible, good impact absorbing foam, such as XRD technology.

Figure 1. Steel – Polycarbonate (PC) – Aluminum (AL) – polypropylene (PP) – PET – 2 no hard shell / only foam.

Figure 1. Steel – Polycarbonate (PC) – Aluminum (AL) – polypropylene (PP) – PET – 2 no hard shell / only foam.

The research shows that when measuring a product’s ability to provide great impact protection, the lower the transmitted pounds of force value, the greater the impact protection. Thus when comparing each of the materials above, we see that EVA offers the least impact protection when used by itself and in combination with PET, PP and AL. But EVA does becomes better at impact protection when combined with steel. On the other side, the data shows that using the 15 pcf XRD material alone (no shell combination) offers excellent impact protection (tied for 2nd best) while also offering greater advantages over the steel shell options (such as flexibility, lighter weight, breathability).

Soft Impact Protection Gear in Team Sports

2nd_skull_logoThere is growing awareness of the devastating effects of sports injuries, from head injuries in football to knee injuries in soccer. There is also evidence that the young brain is especially susceptible to head injuries. This has created changing safety standards, such as in women’s lacrosse. While there is no current or expected requirement for helmets in women’s lacrosse, soft helmets are allowed and being tested for safety standards that are expected to be adopted by US Lacrosse in 2015.

2ndSkull, manufacturer of protective headgear, has a lot of great data and research on impact protection. Did you know:

2ndskill_poron“By freshman year of high school, kids are already staring down at 80 MPH pitches. Wild pitches, line drives, and head-first slides are just some of the ways more than 18,000 kids suffer head injuries each year (baseball & softball).”

2nd Skull products are engineered to reduce impact. Each product includes a thin layer of lightweight XRD® technology.

G-Form Soccer Shin Guard

G-Form Soccer Shin Guard

G-Form is a company in Rhode Island that began by designing soft elbow and knee protective gear with flexible XRD impact protection. They recently introduced a soft shell soccer (international football) shin guard. Athletes experience the from the G-Form shin guard with XRD technology as they did with traditional hard shell shin guards, but the G-Form shin guards are much more conformable and comfortable.

Other examples are found in the work and safety market. We’ve even seen the conservative safety boot market move away from stiff, hard metal foot protection to soft, flexible protection. Additionally, our partners at Blundstone have won numerous design awards, including the coveted for their new with the XRD metatarsal guard.

Blundstone Boot, cutaway

Blundstone Boot, cutaway

Flexible impact protection solutions are replacing hard shell desig ns because athletes are having great experiences with them. Athletes not only reap the benefits of great impact performance, but also the added flexibility naturally improves their performance. Gone are the days of feeling like you are strapping on armor.

Say hello to greater freedom of movement and gear that allows you to focus on enjoying the moment ahead.

Note the slim design of the Blundstone Boot.

Note the slim design of the Blundstone Boot.

The transition from hard to soft shell gear will not happen overnight, and athletes will not see direct soft shell replacements of their traditional hard shell gear. The mammals didn’t replace the dinosaurs directly in their biological niches, but came at them from an angle. The dinosaurs were cold blooded and slow at night, when the first mammals, who were nocturnal, would eat their eggs. When the dinosaurs were active during the day, the mammals slept, still enough to not be found.

Likewise soft flexible protection is being adopted first in individual sports, such as extreme biking, long boarding, and adventure sports, where the athletes make their own equipment decisions. The first adopters include elite athletes looking for an edge or to further enjoy their ride without being restricted. As they adopt thinner, more flexible, and lighter weight protection, others will take notice and search for the same experience.

We’ve already seen evidence of this happening.

It’s happening all around you. People are beginning to see hard shell protection as outdated and old school. The best athletes are enjoying their sports more, and performing better, with soft protection.

Will you be the last dinosaur on the field?

Dave Sherman

Dave Sherman

Technical Design Solutions Manager at XRD® Impact Institute
Dave Sherman is the Innovation Leader at the XRD® Impact Institute - the research, design and testing facility of XRD® Impact Protection Technology. His experience involves a wide variety of foams including polyethlyene, polypropylene, EVA, rubber, polyurethane, silicone, and melamine. He has a Chemical Engineering degree from MIT and an MBA from RPI, as well as over 30 years of experience in the business of developing material solutions to meet demanding customer needs.

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