This post written by Dave Sherman originally appeared on Rogers PORON Cushioning Blog


Rogers and the PORON Team are continually working with a variety of equipment and apparel manufacturers. From helmets to protective vests and footwear to apparel, each market has their own set of standards and testing methods.

We can only begin to imagine how confusing this information can look from someone ‘on the outside’ or who is simply trying to compare one product’s performance and another. To make things more confusing, many markets without pre-set standards or test methods will adopt methods from similar markets.

In light of the March Madness season, we’ll call this next group of standards and test methods “The Elite Eight.” We’ll do our best to break out the types of markets who use these methods and some general information about the tests, but as always, feel free to leave your comments and questions!

Some of the test standards we’ll review are:

1- Peak G
2- HIC – Head Injury Criteria
3- EN 1621-1
4- EN 1621-2
5- NIJ Standard 0101.06
6- EN 13158, BETA 2009 and ASTM F1937
7- ASTM F1614
8- ASTM F2413

Bracket Breakdown:

Head Protection Division

1- Peak G– Peak G measures the maximum deceleration experienced by a projectile (such as an anvil or flat tup) onto the material or product being tested. The Peak G is recorded as the total force returned to the projectile or not absorbed by the product being tested. The lower the Peak G’s, the better the impact protection material. Concussions typically can be recorded around 300 G’s. SNELL M2005 standards require Peak G to not exceed 290 G and DOT standards require Peak G to not exceed 400 G.

2- HIC: Head Injury Criteria – HIC integrates deceleration over time, offering another dimension to just Peak G force. Samples are impacted with 4.6kg, 160 mm diameter projectile with an impact velocity of ~2.8ms¹. Lower HIC scores imply better impact protection and simulate a lower risk/severity of impact-related head trauma – Winner

Motorsports Protective Apparel Division

3- EN 1621-1:1997 assesses devices that are designed to protect the shoulder, elbow and forearm, hip, knee and lower leg regions. The test apparatus consists of a mass of 5kg with a 40mm x 30mm striking face, dropped onto the sample mounted on top of a 50mm radius hemispherical dome. The anvil is further mounted onto a load cell, allowing a measurement to be made of the force transmitted through the protector. The kinetic energy of the falling mass at impact is required to be 50J.

A protector subjected to this test method is deemed to conform to this standard if the average transmitted force of nine tests is less than 35 kN, with no single test result exceeding 50 kN.

4- EN 1621-2:2003 defines two levels of performance for CE approved back protectors. The test apparatus and procedure is similar to that of EN 1621-1:1997, but with a different impactor and anvil configuration that is designed to represent the back. The impactor is a rounded triangular faced prism, of length 160mm, base 50mm, height 30.8mm and radius 12.5mm. The anvil is a radiused cylinder, with its axis orientated to the direction of impact, of height 190mm, diameter 100mm and rounded end radius 150mm.

When tested to the procedure defined in the standard, the two levels of performance are:

  • Level 1 protectors: The average peak force recorded below the anvil in the tests shall be below 18 kN, and no single value shall exceed 24 kN.
  • Level 2 protectors: The average peak force recorded below the anvil in the tests shall be below 9 kN, and no single value shall exceed 12 kN. – Winner!

Protective Vest Division

5- NIJ Standard 0101.06 is the standard for Ballistic Resistance of Police Body Armor developed by the law enforcement standards laboratory of the National Institute of Justice (NIJ), US Department of Justice. The standard has been updated to include additional non-impact test methods such as: complete submersion in water, accelerated conditioning and environmental tests and increased ammunition velocities for some threats.

Depending on the level of the test, typical body armor ballistic testing standards place the body armor over a piece of ballistic clay and measures the back face deformation (or the depth of the hole) after being shot by a particular caliber gun. A Kevlar material is used to ‘catch’ the bullet, but other materials are used behind the Kevlar to decrease this back face deformation. Depending on the level of the standard, back face deformation can range from less than 25 mm to 44 mm depth.

6- EN 13158 (European Norm Certification), BETA 2009 (UK Certification) and ASTM F1937 – 04 (American Society for Testing and Materials) – All standards to specify body protectors used in horse sports and horseback riding

The impact levels are depending on the test level. In all standards, the completed vest is tested by using equipment and test methods similar to the EN 1621 standards. Yet the force that is transmitted through the product is much lower than the motorcycle EN 1621 standards. In addition other factors are recorded in the standard such as fit, minimum thickness of the foam, zipper closures, etc. – Winner over EN-1621 and Ballistic Testing

Industrial Safety Division

7- ASTM F1614 – Measures the transmission of repeated impacts such as a vibration. Often used to compare insole impact levels.
8- ASTM F2413 – Standard specification for measuring footwear protection such as metatarsal guards.

ASTM F2413 is a more stringent test as it records a pass or fail rating whereas ASTM F1614 does not have a standard specification number for pass or fail.

My picks: HIC wins over EN1621-2, and EN12158 beats F2413. Then EN 12158 beats HIC.

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This post authored by John Coonrod originally appeared on the Rog-Blog hosted by Microwave Journal

Microwave circuit designers often have to choose, not only among different layouts and substrate materials, but among transmission-line technologies. Stripline has its advantages for certain components and circuits, and microstrip is popular for both active and passive microwave circuits. But when does a coplanar transmission-line technology make sense?

How do coplanar transmission-line technologies compare with other high-frequency printed-circuit-board (PCB) transmission-line approaches, such as stripline and microstrip? Stripline is often described as a “flattened coaxial cable,” with conductors on the outside of the dielectric material and the dielectric surrounding an internal conductor. Microstrip is even simpler, with a signal conductor on the top of a dielectric substrate and a ground plane on the bottom of the dielectric substrate. It is the most popular microwave transmission technology due to its simplicity and ease of fabrication.

In both stripline and microstrip, the choice of dielectric layer thickness directly impacts how the transmission lines are structured. In both cases, the impedance is determined by the separation distance between the ground layer and the signal conductor, with the two being isolated by the dielectric layer. This can be inconvenient, however, when the dimensions of a circuit are not compatible with the dimensions of a coaxial connector or device pin, where the conductor’s trace width may be too wide to fit between device pins. Some designers will build a taper into a conductor’s trace width in order to make the mechanical connection from conductor to pin or connector, but it is extremely difficult to maintain constant impedance with this approach.

Coplanar transmission-line technologies provide a means of moving signals from a PCB to a connector or device pin without unwanted variations in impedance that can cause signal reflections at higher frequencies. As the name suggests, a coplanar transmission line features a ground conductor that is coplanar with the signal conductor. The impedance is controlled by the line width of the signal conductor and the ground gap. As a result, the impedance can be maintained at some constant value, such as 50 Ω, even as the signal conductor’s width is tapered to a smaller size to meet a pin, and the impedance is maintained without changing the thickness of the dielectric substrate. Coplanar transmission lines come in a variety of configurations, including traditional coplanar waveguide (CPW) and coplanar waveguide with ground (CPWG). Because they can readily make signal transitions from wider transmission lines to relatively narrow terminations without altering the thickness of the dielectric material, they are widely used in CPW test probes for on-wafer testing of discrete and integrated circuits.

(Cross-sectional view of a grounded coplanar transmission line with electric field lines shown)

In terms of modeling, a CPW transmission line is often treated as a metal conductive strip separated by two narrow slots from a ground plane at some distance. The metal strip has a width dimension (W) and the slots have a width dimension (s). The CPW transmission line is symmetrical along a vertical plane. The conductor is separated by the ground plane by the dielectric material. If the dielectric is considered to have infinite thickness relative to the much smaller thickness of the conductor, the CPW structure can be modeled like a parallel plate capacitor that is filled with dielectric material.

Of course, a CPW conductor does have some finite thickness and CPW-based circuits will suffer some losses due to the conductors and the dielectric material. Most of the larger high-frequency design suites, such as the Advanced Design System (ADS) from Agilent Technologies (www.agilent.com) and Microwave Office from AWR (www.awrcorp.com) include CPW transmission-line models. Even some specialized analysis programs, such as Simulink from The MathWorks (www.mathworks.com), and electromagnetic (EM) simulators such as the Sonnet Suites from Sonnet Software (www.sonnetsoftware.com), are effective tools for modeling circuits based on CPW.

CPW-based circuits may appear to offer benefits over other transmission-line technologies, especially when tapered conductors are needed for transitions. CPW supports a large range of possible impedance values, making it possible to fabricate many different circuit functions, such as filters, couplers, and attenuators, with a single PCB laminate material. Microstrip approaches, in contrast, may require the use of hybrid PCB structures formed of laminates with different dielectric constants, to achieve the same range of impedances as CPW.

Laminate materials for CPW-based circuits should be characterized by tightly controlled material thickness and dielectric constant across a board, to ensure consistency of impedance in fabricated CPW circuits. For example, Rogers RO4000® Series high-frequency circuit materials, such as RO4003C™ and RO4350B™ laminates, provide the stable mechanical and electrical characteristics that make them ideal for CPW-based circuits. The former features a z-axis dielectric constant of 3.38 at 10 GHz, while the latter has a z-axis dielectric constant of 3.48 at 10 GHz, both controlled to a tolerance of ±0.05 across the board.

Both materials are hydrocarbon ceramic laminates that can be processed with the low-cost fabrication techniques used for FR-4 materials, except these are substrates engineered for higher frequencies. In addition to supporting extremely stable impedance by their controlled dielectric constant, they also feature a coefficient of thermal expansion (CTE) that is tightly matched to that of the copper conductor metal, so that both conductor and dielectric expand and contract together with changes in temperature. This results in excellent mechanical stability and high reliability when plated through holes (PTHs) are needed to connect different layers in a multilayer assembly.

Multilayer circuits are becoming more commonplace at higher frequencies, and these circuit constructions often consist of multiple transmission-line technologies, such as CPW and microstrip. As important as maintaining constant dielectric constant for controlled impedance lines, the tight tolerance in the laminate’s dielectric constant is critical for fabricating controlled-impedance transitions between microstrip and CPW, or CPW and stripline circuits. Both RO4003C and RO4350B laminates provide the levels of electrical and mechanical performance that makes them well suited for use in CPW designs.

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In case you missed it, a revealing study was conducted on SanFlickr Creative Commons/miggslives
Francisco’s BART (Bay Area Rapid Transit) system that tested the cleanliness of the seats on a BART rail car.  There have been complaints in the past about a cleanliness problem.  Some passengers take measures of standing up on the train just to avoid coming into contact with the seat cushion material.

The Bay Citizen commissioned Darleen Franklin, a supervisor at San Francisco State University’s biology lab, to analyze the bacterial content of a random BART seat.

Fecal and skin-borne bacteria resistant to antibiotics were found in a seat on a train headed from Daly City to Dublin/Pleasanton. Further testing on the skin-borne bacteria showed characteristics of methicillin-resistant staphylococcus aureus, or MRSA, the drug-resistant bacterium that causes potentially lethal infections, although Franklin cautioned that the MRSA findings were preliminary.

High concentrations of at least nine bacteria strains and several types of mold were found on the seat. Even after Franklin cleaned the cushion with an alcohol wipe, potentially harmful bacteria were found growing in the fabric.

Source: The Bay Citizen (http://s.tt/129fS)

It’s Not Your Customer’s Fault

Can you say “Yuck!”  Apparently replacement cars are on the horizon.  It sounds like BART is considering a plastic-type seat and sacrificing comfort.  Why does the customer always get the hit when it comes to riding public transportation?  It even went as far as asking riders to use hand sanitizers….making it their problem:

“… encouraged riders to wash their hands and use hand sanitizers available at BART stations.”

Hygiene has emerged as a key issue as BART officials determine what kind of seats to install for a new fleet of cars in 2017. In January, system employees were invited to test a variety of seat models at a Hayward warehouse. One employee, Melissa Jordan, filed a report on BART’s website about the trade-offs in selecting the new seats.

“Can I live with some type of seat that’s less cushiony — maybe padded vinyl instead of fabric — if it’s easier to keep clean?” Jordan wrote.

Source: The Bay Citizen (http://s.tt/129fS)

Alternative Seating For Comfort and Clean

The reality is, there are alternatives to seat materials that allow for both comfort AND cleanliness.  Rogers develops materials and seat cushions that do exactly that.

One of the issues facing the current BART seats is the polyurethane foam material under the upholstery.  While it is true that the upholstery itself should be of a bacteria-resistant non-woven material, the foam beneath must also not be a breeding ground for bacteria.  One solution to preventing bacteria growth is to build  cushions from open cell silicone foams!  There is a standard known as ASTM G 21:  Resistance of Synthetic Polymers to Fungi.  The test measures the growth of specific bacteria specimens and organism mixtures.  For those familiar with such bacteria, the ones observed are ATCC 9642, 11797, 6205, 9645, and 15233, with technical names such as aspergillus niger, penicillium funiculosum, and others.  The test uses a rating system from:

  • 0-4 where 0 is no trace
  • 1 is trace (<10%)
  • 2 is light (10-30%)
  • 3 is medium (30-60%)
  • 4 is  heavy (>60%).

Silicone foams for seating cushions receive ratings of either 0 or 1.  The problem with polyurethane materials filled with flame retardant agents (required for subway system passenger seating cushions) is that the fillers compromise the foam causing it to crumble over time and have large porous voids, which becomes a cesspool for bacteria and all kinds of spills.

The new BART specification for future builds already specifies silicone foam for all seats – however, why should the ridership have to to wait for the funding for those new build cars – when the seats could be changed out TODAY with refurbishments and replacements that use the silicone foam.

Besides resistance to bacteria growth, the silicone material is also resistant to fire spread and adheres to the smoke, and toxicity requirements of for subway passenger seating.

Finally, there is comfort.  A silicone foam will not deteriorate or change in its comfort-performing capabilities for a minimum of ten years!

Now BART has an answer to its problem.

Related Links about Rogers Silicone:

Video on Rail Car Seating 101: http://blog.rogerscorp.com/2011/03/04/rail-car-seating-101-silicone-vs-polyurethane/
Silicone Articles:  http://www.rogerscorp.com/hpf/bisco/articles.aspx
Silicone Materials: http://www.rogerscorp.com/hpf/bisco/producttype/4/Bun-Silicones.aspx

Creative Commons Image source: http://www.flickr.com/photos/miggslives/4782378772/

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In catching up on some internet reading, I came across this press release from Frost and Sullivan that talked about Megatrends and how those trends are driving growth in key markets, particularly Chemicals and Materials.  Frost and Sullivan defined Megatrends as “global, sustained and  macroeconomic forces of  development  that impact business, economy, society, cultures and  personal lives, thereby defining our future world and its increasing  pace of change.”

At Rogers, we are committed as a company to innovation around three key Megatrends that directly relate to how our materials help make a better world.  Our three Megatrends are:  Internet Growth, Clean Technology and Mass Transit.

What was interesting was seeing the overlap with what Frost is saying with the direction we are seeing in our business:

“Megatrends will have a profound impact on the future direction of the chemicals and materials industry,” notes Frost & Sullivan  Industry Principal Brian Balmer. “For instance, the growth of mega  cities will stimulate growth for many chemical products such as glazing  with added acoustic insulation, and materials such as plastics and adhesives that enable the production of more compact home appliances.”

“Over the longer term, continued urbanisation in developed countries will result in demand for more materials that contribute to making  ‘healthier’ buildings…  Similarly, social trends, in particular for more environmentally  sustainable solutions, will be the single biggest factor affecting  future chemicals demand,” states Balmer.

“Products designed for modern and future lifestyles (‘GenerationY’) use a wide range of innovative chemicals,” remarks Balmer. “These  include structural materials such as engineering plastics for more  compact and more feature-packed convergent devices such as smartphones,  composite materials for lighter, stronger sports equipment and  eco-friendly materials for bio-sourced, recyclable, re-usable or  bio-degradable packaging.”

Product areas that will emerge at the forefront in future due to the impact of Megatrends range from nanomaterials, smart materials and  sustainable/renewable materials to organic electronics, biotechnology and carbon fibre and engineered natural fibres. Their growing presence will, in turn, have ramifications for several  chemicals.

Looking at our Megatrends, here’s what we see:

1. Internet Growth

As the internet continues to expand, mobile data traffic is expected to double every year through 2014, while Internet traffic will expand 46% annually. Demand for speed and bandwidth of network systems, and sales of smart phones, tablets, and mobile computers are expected to increase at double-digit rates.

Rogers is responding with:

  • Printed circuit materials critical to high speed performance of fast-growing wired and wireless 3G and 4G infrastructures
  • High performance foams to seal and protect top brands of popular smart phones, tablets, and notebook computers

2.  Clean Technology

Demand for clean technologies will grow rapidly over the next five years and beyond, with deployment of renewable energy and highly efficient technologies to reduce carbon emissions for the transport sector and for energy efficiency in buildings, industry and agriculture.  This trend is driving the need for specialty materials to enable new hybrid/electric vehicle technologies, improve motor efficiencies, and increase wind and solar energy performance.   Includes technologies in renewable energy (wind power, solar power, biomass, hydropower, biofuels), information technology, green transportation, electric motors, green chemistry, lighting, and many other appliances that are now more energy efficient.

Rogers is responding with:

  • Power electronic solutions for wind and solar power conversion over long distances
  • CleanTech materials to seal and protect batteries in hybrid electric and electric vehicles

3.  Mass Transit Expansion

Increasing urbanization and steady growth in urban populations worldwide, combined with the drive for sustainability, is driving demand for Mass Transit solutions (rail, aircraft, bus, and others) worldwide. Railways in India and China are expanding at a rapid pace. New components are in constant demand, and complexities of Mass Transit require innovative, high-reliability products and materials to ensure passenger safety.

Rogers is responding with:

  • Power electronic components and thermal insulation for power conversion in rail propulsion systems
  • Robust seating, sealing, and vibration isolation cushioning that meet stringent requirements for long life and passenger safety

And while it’s good to be on the forefront of trends, Rogers continues to be committed to evolving our materials to better serve the needs of our customers.  We work hard to stay close to understanding the needs of the design engineers who reach out for help.  Let us know how we can better serve you.  We’re here to assist.

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This post written by David Sherman originally appeared on Rogers PORON Cushioning Blog.

You’ve probably heard quite a bit about concussions in the news lately.  In recognition of Brain Injury Awareness month, which takes place in March, the Brain Injury Association of America (BIAA) is launching a nation-wide campaign to ensure coaches of school athletic teams and extracurricular athletic activities are trained to recognize the signs and symptoms of concussions.

All of us at Rogers are excited to see that proper attention is finally being brought to the causes and effects of brain and impact injuries.  Extreme impact protection is the very reason we developed our PORON XRD technology, which is not only used in helmets, but also in compression garments, elbow and knee pads, and protective footwear.

As we travel around to trade shows all over the world, we are consistently asked how PORON XRD Material works.  How can such soft, flexible and breathable foam protect against something like a baseball flying at 100mh?  It all has to do with a short lesson in physics 101 and strain rate dependant materials.

Strain rate dependent materials are used in a variety of protective applications mentioned above.  They are useful in these applications because of their unique ability to adapt to the applied impact.  At low strain rates the material feels soft and contours to the body.  While at high strain rates the material instantaneously stiffens to absorb the impact and then returns to its original ‘resting’ state.

For those who want more technical information….

PORON XRD Material gets its softness when at rest or simply being worn, by being above the glass transition temperature (Tg) of the urethane molecules.  (Glass transition temperatures are similar to a melting point – for those who are not the foam geeks that we are.)

When stressed at a high rate or impacted quickly, the glass transition temperature of the material goes up to the point where the urethane momentarily “freezes.”  (Think of water freezing into ice.)  Many materials have glass transition temperatures, which is why strain rates are always specified in material testing.

When impacted, it is the firming of the material that allows PORON XRD Material to instantly form a comfortable, protective shell around the wearer.  Unlike many other materials which often maintain their “frozen” state, PORON XRD Protection immediately returns to its soft, flexible and contouring state.

For a more visual example, think of diving into water at a low height versus a higher height.  At low heights, jumping into water feels very soft and helps cushion the dive.  But at high heights (i.e. jumping from a bridge) the water feels like frozen ice.  This is due to the speed at which the person is entering the water.

Another example is to envision removing a Band-Aid™.   If you remove a Band-Aid ™ slowly, the

adhesive sticks to the surface, but if you remove it quickly, the adhesive freezes and sticks less.

PORON XRD Material was engineered to react very quickly in various impact situations.  For example, PORON XRD Technology is effective at absorbing not only smaller, repeated impacts (such as nudging players during a basketball game) but it is also effective at absorbing larger impacts (such as in a ballistic vest applications).  Rogers’ ability to manipulate the PORON XRD chemistry makes this unique material soft and flexible at rest or when it’s wrapped around your body, but instantly absorbs energy upon impact.

If you would like more information on all the various testing methods that we have conducted on PORON XRD Materials, we have plenty to share!  Just give us a comment below.

Please come back and visit us!  We will be posting some interesting news over the next several weeks in collaboration with our PORON XRD partners in recognition of Brain Injury Awareness Month.   As always, we would love to hear your questions and comments/views you may have on our products as well as how brain injuries/concussions are treated among team sports.

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