Biomedical Engineering Reference
In-Depth Information
elastic response is observed in the tissue. The hysteresis energy may dissipate as
heat or in the drag of the fluid that is exuded and absorbed during loading and
unloading, respectively. The use of airbags in automobiles and a fluid-containing
pad system are also based on energy-absorbing mechanisms. An energy-shunting
configuration is used to distribute impact loads away from the vulnerable area to
the surrounding soft tissue. For example, hip protectors and wrist guards use hard
shells that shunt energy away from the joints, which are more vulnerable to injury.
A number of organizations mandate the required standards in designing, devel-
oping, and testing safety equipment. The National Operating Committee on Stand-
ards for Athletic Equipment fosters and encourages the dissemination of infor-
mation on research findings on athletic equipment, injury data, and other closely
related areas of inquiry. In terms of automobile safety, the Federal Motor Vehicle
Safety Standard (FMVSS) has established various testing protocols. Furthermore,
in testing to develop protective gear during a crash, biomechanical analyses are
carried out using artificial bodies or joints (popularly known as dummies). Dum-
mies are developed to mimic few physiological joint structures, ligaments, muscle
response, and bone response.
Problems
5.1
Consider an arm, abducted 20
from the surface, of a person of 150 pounds
with a 20-pound weight (as shown in the figure). The angle of insertion of the
abductor muscle is 25
°
and 2 inches from point A. The arm weight is typically
5% of the body weight and the center of gravity is four-ninths of the total
length from the proximal end. What is the force generated by the muscle?
°
5.2
Ali wants to carry some weight in his hand maintaining a static position, as
shown in the figure. The weight of his forearm and the hand is 3 kg with a
center of mass at 21 cm from the elbow joint. The weight is at 29 cm from the
elbow joint. The elbow flexion muscle is attached at 3 cm from the elbow joint
and can exert a maximum force of 2,500N. Calculate the mass of the heaviest
ball that Ali can hold statically in that position.
