T
extile production has been at the center of the evolution of manufacturing from very
early times. Textiles touch so many aspects of people’s lives, and the ways of making and enhancing
them have advanced over millennia. Textile technology developments were prominent in the escalation
of manufacturing activity that defined the Industrial Revolution; and the conversion of basically
manual processes to power-driven, resource-consuming technologies, as well as the increasing use of
toxic process chemicals whose residues were released into the environment, contributed
significantly to the acceleration of environmental degradation that became a hallmark of industrial
development.

In support of efforts in recent years to reverse the impacts of this degradation on quality
of life and the balance within Earth’s ecosystem, the textile industry once again has a significant
role to play. Enlightened manufacturers are redesigning processes and products to reduce their
environmental impact. In the process, they are reducing energy usage and replacing fossil fuels
with renewable and alternative energy resources when possible or practicable. They are reducing
water usage as well as waste and emissions volumes, and reclaiming and recycling materials that
would otherwise be disposed of and giving them renewed purpose. They are choosing earth- and
people-friendly process chemicals to replace more toxic ones. And these enlightened measures not
only restore the ecological balance and safeguard human health, but also often benefit a company’s
fiscal health.

In a series of occasional articles,

Textile World
will examine how some textile manufacturers are transitioning operations to increasingly
sustainable models. This first article focuses primarily on renewable and alternative energy and
improved efficiencies, taking into account other aspects of sustainability if they apply here.
Later articles will focus on other aspects of sustainable textile manufacturing.

Interface

Atlanta-based modular and broadloom carpet manufacturer Interface Inc. has been measuring
progress in its journey toward becoming a “restorative enterprise” — one that ultimately gives
back to the planet more than it takes — since 1996, two years after company Founder and Chairman
Ray Anderson’s “epiphany” regarding the notion that business and industry must take the lead in
reversing the environmental damage they have wrought. The company’s goal of reducing its
environmental impact to zero by 2020 includes deriving all of its energy from renewable resources.
Its effort to reach that goal also includes revamping manufacturing processes to reduce energy
usage; upgrading heating, ventilation and air conditioning systems; installing skylights; and
improving the efficiency of artificial lighting systems. “This is a much bigger part of our
initiative than renewable energy,” said Erin Meezan, the company’s vice president, sustainability.

Since 1996, Interface has reduced total energy use per unit of output at its carpet
manufacturing plants by 44 percent, and non-renewable energy use per unit by 60 percent. Renewable
inputs such as solar, hydroelectric, landfill gas (LFG) and geothermal now provide 28 percent of
its total energy needs. Globally, seven of its manufacturing plants use 100-percent renewable
electricity; and 89 percent of its overall electric power is renewably sourced, including power
received directly from the grid, purchased as renewable energy certificates (RECs) or generated
on-site.

Interface also has cut net greenhouse gas (GHG) emissions by 71 percent since 1996, with 34
percent coming from reductions and 37 percent from offsets.

Milliken & Company

Spartanburg-based textile and chemical manufacturer Milliken & Company has been
measuring its energy consumption since the early 1990s. According to Cassidy Carlile, director of
corporate environmental, the company generally sets energy reduction goals of 5 to 10 percent per
year. Its GHG emissions from operations have been reduced by 28 percent since 2000. When carbon
sequestration in the company’s considerable forest acreage is added in, Milliken is certified to be
a carbon-negative manufacturer — the only textile or carpet manufacturer to achieve that status.

Milliken receives 5 to 10 percent of its total power needs from its hydroelectric plant in
South Carolina, which provides power to a couple of local plants, with the rest sold locally and
into the grid. The company’s LaGrange, Ga., carpet manufacturing plant uses more than 80 percent of
the LFG produced at the LaGrange landfill, which also provides LFG to Interface’s carpet plant in
LaGrange. LFG comprises 20 percent of the boiler fuel consumed at Milliken’s plant. An LFG project
also is underway to provide fuel to its plant in Inman, S.C.

Since the mid-1990s, wastewater biosolids have been used as boiler fuel at Milliken plants
where they are generated. “This has allowed us to take them out of landfills and get energy value
out of them as well,” Carlile said. The company also diverts solid waste to waste-to-energy (WTE)
facilities for use by other entities.

Shaw Industries

Dalton, Ga.-based Shaw Industries Inc. — a manufacturer of carpet, hardwood, laminate and
tile flooring products — annually converts some 18,000 tons of post-industrial carpet waste and
wood flour to steam energy at its WTE gasification plant in Dalton, reporting the energy produced
saves more than 2.5 million gallons of fossil fuel at an adjoining laminate plant. Another project
called Re2E (Reclaim-to-Energy) is underway that will convert more than 38,000 tons of
post-industrial and post-consumer carpet to provide more than 90 percent of the steam and half of
the electricity needs at one of its carpet plants in Dalton. The project is expected to cut steam
production costs significantly.

Shaw’s Andalusia, Ala., yarn plant is replacing some of the diesel fuel that backs up the
natural gas used in its operation with biodiesel derived from used cooking oil it collects from
local businesses, employees and the City of Andalusia. Cary Baker, the plant’s director of
operations, said the “Yellow Grease” reduces the plant’s fuel costs as well as suppliers’ disposal
costs. “We’ve probably saved $10,000 to $12,000 year-to-date,” he said, adding that the savings are
transferred to the plant’s freight account to improve competitiveness in that area of the business.

These measures support Shaw’s goal to derive 10 percent of its power from alternative
sources by 2017 as well as reduce waste sent to landfills.

Victor Group

Hydropower is the source of more than 91 percent of the energy used by Canada-based
contract, residential, outdoor and apparel fabric producer Victor Group Inc. at its Canadian
locations. In addition, the company’s manufacturing facility in Fall River, Mass., offsets a
portion of its electricity usage internally with RECs from the Canadian operations, and is
investigating local green energy options for future use if needed, according to Paul Bennotti,
marketing director.

FesslerUSA

Orwigsburg, Pa.-based knitwear and fabric producer FesslerUSA expects to provide 90 percent
of its electricity needs from a 1-megawatt solar array planned for its Deer Lake manufacturing
plant, making it immune to an expected 40-percent jump in Pennsylvania’s industrial electric rates
after the first of next year. The company also has installed more efficient lighting and variable
speed drives on some motors, and applied reflective paint where it can be effective, said Jenny
Russo, financial analyst.



November/December 2009

T
he street sign at ILC Dover’s headquarters — One Moonwalker Road — gives a strong hint
about what goes on inside the 260,000 square feet of office, development and manufacturing
buildings located there: Spacesuits for the Apollo astronauts in the 1960s and ’70s; gear for the
space shuttle crew that repaired the Hubble telescope in May 2009; and now, inflatable houses
designed for future outposts on the Moon — or even Mars. ILC may need to come up with a new street
name.

A leader in the development of flexible material systems that withstand extreme
environments, Frederica, Del.-based ILC has provided solutions to the National Aeronautics and
Space Administration (NASA) since the early days of the US space program. The company designs both
hardware and softgoods for the wide-ranging challenges of space exploration — from the high heat
of re-entry, to the profound cold of a lunar night, to the airbags that cushioned the landings of
the Mars Rovers. ILC makes a multitude of earthbound commercial products as well, from innovative
containment systems for packaging powder pharmaceuticals to highly advanced protective military
gear.

Still, it’s the inflatable lunar habitat idea that grabs one’s imagination. From the first
Moon landing in 1969 to the last trip there three years later, no one ever spent more than three
days on the surface, and they took the lunar module with them when they left. In the 21st century,
NASA’s Constellation program — to return to the Moon, set up a permanent base, and from there send
people to Mars – started taking shape. This program created a host of new challenges, including the
most basic one: if a crew is living on the Moon for months on end, where is everyone going to
sleep?

Launching A House Into Space

ILC’s engineers are working on the answer to that. In partnership with several different
branches of NASA, including Langley Air Force Base and the Johnson Space Center, the company has
been developing ideas for different configurations of lightweight space habitat structures.

“There’s a keen interest among the Constellation management and engineers for softgoods
solutions,” said Cliff Willey, ILC program manager of space inflatables. “When you are launching
equipment into space on a rocket, everything needs to be as lightweight as possible, packed
densely. In the case of a habitat, you want to be able to deploy something that can expand to be
much bigger on the surface of the Moon without a lot of mechanism. An inflatable, soft item is very
good for that.”

ILC recently completed the design work on one such project, a “mid-expandable” habitat with
two hard endcaps and a deployable softgoods section in the center. The endcaps for the current
prototype are being built by NASA Langley Research Center out of low-cost metal, but a lightweight
aerospace composite is envisioned for lunar deployment to reduce mass. For transport, the softgoods
section packs into the endcaps. During deployment, it is unfolded and inflated by air pressure,
more than doubling in length. The midsection’s unique fabric lobe system allows for a structure
that is much lighter in weight but has a higher volume than a similar hard-material configuration
would be. The endcaps are where doors, airlocks and other structures are mounted.

Harsh Lunar

Environment Poses Unique Risks

The Moon’s environment contains a host of external hazards, including extreme temperature
fluctuations — which softgoods withstand much better than metals — plus radiation, dust,
bombardment from micrometeoroids, and low gravity. All these are taken into account by engineers
designing the lunar habitat, which has as many as 10 outer protective attenuation fabric layers
built up over two internal structural layers. Although exact material specifications are still
under study, the outermost attenuation layer will likely be constructed of Ortho-Fabric, which
consists of a blend of Gore-Tex®, Kevlar®, and Nomex® materials. The thermal micrometeoroid portion
of the attenuation layers might be constructed of layers of aluminized Mylar®, laminated with
Dacron® scrim.

But the biggest challenge ILC’s engineers faced when designing the multi-layered habitat was
not external: It was the inflation pressure on the two innermost layers of the structure. “You have
to come up with a pretty clever design to handle the high loads inside a dwelling that is
pressurized to a level in which astronauts can live,” said Ric Timmers, ILC senior analysis
engineer. “The skin load on the internal layers is proportional to the internal pressure times the
radius, so you need to find a material that’s able to handle the pressure on a big structure like
this one, which is 3 meters in diameter.”

In the zero-atmosphere Moon environment, not only do you need to control for oxygen leakage
through the habitat walls, but also, any significant fabric failure would result in a devastating
outward explosion of the structure. ILC’s solution was to design an interlocking webbing net over a
gas-impervious, coated fabric. The 2-inch-wide webbing is constructed of Vectran® in a plain weave
and has an advertised breaking strength of 24,000 pounds. The fabric was deliberately oversized so
that it would bulge slightly between the webbing panels, transferring the pressure load to the
webbing. This unique combination of fabric and webbing working together would allow the habitat to
be inflated to 9 pounds per square inch (psi), an acceptable pressure for humans living on the
Moon, while meeting NASA’s space construction safety standards.

Physical Prototyping

Would Send Costs Out Of Orbit

Testing the integrity of the design on the Moon’s surface was obviously impossible. Building
numerous prototypes out of custom fabric, and pushing habitat models to destruction, would also be
prohibitively expensive, as well as time-consuming. 

“Earlier, we were contemplating building a test rig and physically measuring the pressure
load on the fabric, the tension in the webbings, the pressure behind the windows — all
simultaneously — but we were looking at well over $1 million for a test like that,” Willey said.
“That’s when we backed off and decided to go with realistic simulation. We couldn’t be Edisonian
about this, relying on trial and error. We had to be able to build a reliable, finished product
design the first time out.”

Realistic Simulation

Provides Down-to-earth Answers

So, the group turned to Abaqus finite element analysis (FEA) software, from the SIMULIA
brand of France-based Dassault Systèmes, to test virtual models of the fabric and webbing under
varying load scenarios. They also used FEA to evaluate the robustness of some minor structural
components, such as the metal brackets holding the webbings. “We relied heavily on analysis with
Abaqus for this project,” Timmers said. “It would have been pretty risky to do this without FEA —
you had to sleep at night!” 

Abaqus/CAE, the pre- and postprocessor for the Abaqus Unified FEA product suite, was used to
model the 3-D geometry of the design as the basis for the simulation. The group then ran the
simulation models with two central processing units on a Linux machine using Abaqus/Standard, which
provides all the material, geometry, and loading nonlinearity needed to simulate fabric structures.
“Our models were fairly straightforward, so static loading was appropriate for what we needed to
know,” Timmers said. 

FEA Helps Identify

Safe Fabric Yield Strength Limits

ILC began its analysis of the fabric/webbing system by modeling a unit cell of fabric
constrained by a square of the webbing net. “We used a simple planar approach for this analysis
since the out-of-plane curvature of each unit cell was negligible relative to the full radius of
the entire habitat,” Timmers said. When setting up the model, the group measured the sides of the
cell from webbing center to webbing center instead of from webbing edges. “We used the midpoints
rather than the edges because we wanted to be more conservative in our analysis by imagining that
the webbing wasn’t there, as a sort of worst-case scenario,” Timmers said.

To model the fabric itself, membrane elements were selected, and all degrees of freedom at
the perimeter of the unit cell were held fixed. Then, the model was oversized slightly, using what
Timmers calls “a neat thermal expansion coefficient technique” that raised the temperature until
the fabric expanded to a set percentage, to simulate the bulge of fabric between webbings. Finally,
the nominal 9 psi of pressure was applied to the model, and Abaqus calculated the resulting stress
in the material. With a center load result of 74 pounds per inch (lbs/in), and an edge load of 84,
the material was well within NASA’s required safety factor of four, as the ultimate tensile
strength of the fabric was approximately 500 lbs/in.

“Using Abaqus FEA to identify the allowable limits of the fabric’s performance was very
useful because with this type of structure you have to be really sensitive to total mass,” Timmers
said. “When we found one material that worked, we could use Abaqus to virtually test another,
lighter material to see how much we could save on total weight and still provide the right factor
of safety.” The final fabric selected for the lunar habitat was a 0.0075-inch-thick, 200-denier
Vectran with a urethane coating impermeable to gas leakage. The weave is plain, with a yarn count
of 50 by 50 threads per inch. The ultimate tensile strength is 551 lbs/in in the warp direction,
and 520 lbs/in in the fill direction.

Keeping The Web Of Safety Intact

In addition to low stress in the fabric restraint system, another important contributor to
the habitat’s stability was evenly balanced loading of the ring of webbing itself. To test this
part of the design, the ILC team used Abaqus to simulate just the critical axial, or end-to-end,
length of the webbing. Hoop webbings around the circumference are more isolated from one another
and are less sensitive to any uneven lengths among them. The purpose of the model was to simulate
“manufacturing uncertainties” that might unexpectedly shorten the length of a single webbing.

“Our biggest concern this time was that any deviation in the length of one webbing could
foreshorten the whole system, concentrating 100 percent of the load on a single section and leading
to a cascade of breakage,” Timmers said. The team set up their model with all 26 axial webbings
fixed to a flat plate representing the hard endcap of the habitat. The usual 9-psi pressure load
was applied to the surface of the plate to simulate conditions in an inflated habitat. When one
webbing was shortened by just 0.125 percent, the analysis results showed that the load on it jumped
to 4,815 pounds, versus 3,600 pounds on the rest of the webbings. But since the breaking strength
of the Vectran webbing chosen for the habitat was 24,000 pounds, the safety factor of four was
still met.

How long will such a well-designed structure last on the Moon? “The intended design life of
the lunar habitat is at least 10 years,” Timmers said. While accelerated aging studies on the
component materials and creep testing on webbing material have already been carried out, additional
long-term durability studies are still pending.

Camping On The Moon, Mars

— Or Even Just The Antarctic

With their habitat design complete, ILC teamed with NASA to build a prototype for “Camping
on the Moon,” now on display at NASA Langley. Real-world verification tests of a full model —
including a deployment run-through, a high-pressure test, and tear-resistance evaluation — are
pending further funding.

“We may very well run these tests ahead of time with Abaqus,” Timmers said. “It’s ideal to
use a combination of modeling and testing back and forth, applying FEA to dial into just a few
possible scenarios.”

Whatever the timeline for deploying astronaut habitats on the Moon or Mars, ILC’s unique
approach to such structures has applications closer to home as well: potentially as hyperbaric
chambers for health clubs or hospitals; or, already, as dwellings for polar- or desert-based
scientists. A similar habitat designed with Abaqus Unified FEA has been tested in the harsh
environment of the Antarctic and will be going to the Arctic as well. The polar habitat model had
requirements around wind, snow and ice loading, all of which are absent on the Moon, so the
material selected was several layers of polyurethane-coated nylon separated by layers of
Thinsulate™.

What will the address be in the Arctic — One Icewalker Road? The ILC engineers hope One
Marswalker Road is not that much farther away.

Editor’s Note: Lynn Manning is a science and technology writer based in Providence, R.I.