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A D V A N C E D
M A T E R I A L S
&
P R O C E S S E S | J U L Y / A U G U S T
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Impact testing of a ski boot determines
fracture properties.
B
iomechanics
applies established
mechanical principles to bio-
logical structures and functions
as they relate to the body in motion.
By applying the laws of mechanics to
the human body, engineers can ana-
lyze professional athletes and develop
materials that will enhance perfor-
mance and help prevent sports-related
injuries.
Many sporting goods manufac-
turers pay close attention to material
performance, especially with regard
to footwear, clothing, and protective
equipment. Even with improvements
that help minimize injury risk, damage
and wear often still occur. Some of the
most common ligament and tendon
tears, along with broken bones, occur
during sports-related activities. There
is a rising demand from both profes-
sional and recreational athletes to
improve injury-related recovery times
and increase therapy options. For
sports and recreation equipment man-
ufacturers and sports medicine clini-
cians, mechanical testing is essential
to optimize material performance,
minimize injury, and improve recovery
outcomes.
ATHLETIC FOOTWEAR TESTING
Footwear is one of the most
important aspects of all athletic
endeavors, with significant resources
invested into the design of high-
performance
footwear.
Therefore,
testing plays an important role in ath-
letic shoe research and development
efforts. For example, engineers often
investigate the impact and rebound
performance of different materials
and structures. Intense activities such
as long-distance running, soccer,
and basketball often place excessive
mechanical loads on footwear that can
result in impact forces of more than
10 times an athlete’s body weight.
Today’s athletic wear manufac-
turers are designing and developing
shoes with high-performance soles,
which often incorporate air cushion-
ing, gel-filled capsules, or both. One
type of mechanical test manufacturers
use to guide design is
energy return
.
Mechanical fatigue testing evaluates
the behavior of different parts of the
sole and helps identify parameters such
as dynamic stiffness and the ability to
absorb energy.
Some fatigue testing machines
allow users to import complex wave-
forms to simulate a runner’s gait. Deter-
mining the mechanical performance of
complex viscoelastic materials in shoe
soles is critical to improving athletic
footwear design. Optimizing this per-
formance helps reduce ankle, knee, and
hip stress, and ultimately enables ath-
letes to move faster and avoid injury.
TESTING ENHANCES
PROTECTIVE GEAR
Sports safety and sports-related
injury are hot topics, especially as they
pertain to high-impact activities such
as football and hockey. In these sports,
the dual objective of equipment suppli-
ers is to both enhance performance and
minimize injury. In recent years, hockey
and football equipment manufacturers
have increased their impact testing and
static testing to ensure that protective
gear functions correctly.
For example, equipment designed
to reduce bodily impact, such as shoul-
der and body padding, is tested to deter-
mine the amount of energy absorbed.
Also, because protective materials are
often bulky and cumbersome for ath-
letes towear andmaneuver in, manufac-
turers are constantly looking for lighter
and more breathable materials that do
not sacrifice impact resistance.
Protective gear, such as helmets,
is also impact tested to determine the
strength of the outer helmet shell, inner
cushioning, and strap. One key compo-
nent of helmet design is the ability to
distribute impact shock. The amount
of force transmitted through the helmet
can be quantified using multiple strain
gauges mounted to both a dummy
headform and external helmet. Today’s
helmet design has drastically improved
with an abundance of resources contin-
ually invested and greater awareness
of head health issues. Helmets are now
multilayered and combine impact-ab-
sorbing pliable materials to reduce
concussions and protect athletes from
impact-related injuries.
BIOMATERIALS DEVELOPMENT
AND TESTING
While impact-related injuries are
common in professional football and
hockey, some of the most prevalent
injuries among other professional
athletes and recreational players are
muscle pulls and tears, especially in
knees and shoulders. A tear to the
anterior cruciate ligament (ACL) is one
of the most severe sports injuries and
requires surgery to restore. Proper
repair of an ACL tear may require sev-
eral months of healing depending on
the patient’s age and health. Unfortu-
nately, this injury is sometimes serious
enough to shorten an athletic career.
Many biomedical companies are
focusing on ways to improve musculo-
skeletal healthcare. Not only are they
investing in creating better equipment
for surgeons and doctors, but they
are also investigating new biomateri-
als. A major initiative of biomaterials