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ENERGY ABSORBING PRODUCTS
Within the family of antivibration products, we are introducing a line of ENERGY-ABSORBING PRODUCTS.
GENERAL
In order to lend full understanding of the importance and capabilities of this product line, we will deal with the concept of ENERGY as well as present some practical
examples of several applications. The examples will also include calculations of the forces involved.
Energy-absorbing components are often used as parts of a system or a device itself or, alternatively, they might be used as a safety measure to absorb runaway energy in
case of failure of a component or a system. Some numerical examples are addressing both types of these applications.
ENERGY
A body is said to possess energy if it has the ability to perform work. This ability can be the result of its position or its condition. The position of the body produces
POTENTIAL ENERGY, whereas if the body is moving with some velocity it possesses energy of motion or KINETIC ENERGY.
The formulas governing energy are as follows:
Kinetic Energy of a body in translation
mV2
where m is mass:
m =
V is velocity in in./sec or ft./sec
W is weight in lb.
g
is acceleration of gravity 32.16 ft./sec2 or 386 in./sec2
Kinetic Energy of a body in rotation
E = Io•32 .....................lb. in. or lb. ft.
where Io is the mass moment of inertia about the axis of rotation in lb. in.sec2 or lb. ft.sec2
3 is angular velocity in rad/sec or 1/sec
Potential Energy
E = W•h .....................lb. in. or lb. ft.
where W is weight in lb.
h is height of free fall in in. or ft.
If the velocity at the end of the free fall is needed, it can be found from:
V = 2gh
The total energy is considered the sum total of all energies involved, and this is the amount which is available to perform work.
In the examples which follow, simplified formulas have been developed and used to provide a very close approximation. This enables the application of units which are
most commonly used. The nomenclature used in these examples are as follows:
The actual nature of the application and the availability of space will determine which type of Bumper will be used. In order to facilitate the choice, the following graph is given
which compares the Force vs. Travel characteristics of the different types.
Bumper Technical Information
Continued on the next page
2
W
g
.....................lb. sec2/in.
or lb. sec2/ft.
.....................lb. in. or lb. ft.
.....................in./sec or ft./sec
E1
Kinetic energy (lb. in.)
E2
Work (propelling force) Energy (lb. in.)
E3
Total energy (E1 + E2 lb. in.)
E4
Total energy (E1 + E2) Per Hour (lb. in.)
WE
Effective weight (lb.)
W
Weight of object (lb.)
V
Velocity (ft./sec)
F
Propelling force (lb.)
C
Cycles per hour
HP
Motor energy (horsepower)
T
Torque (lb. in.)
g
Acceleration due to gravity (ft./sec2)
H
Falling height including stroke of shock absorber (in.)
S
Shock absorber stroke (in.)
t
Deceleration time (sec)
a
Decelertaion (ft./sec2)
u
Friction (coefficient)
RS
Shock absorber mounting radius (in.)
K
Distance from pivot to center of gravity (in.)
VS
Velocity at the shock absorber (ft./sec)
q
Reaction force (lb.)
This drawing shows size comparison of identical capacity
bumpers from each product group. The graph at the right shows
comparable performance characteristics.
V10P80-A01
V10P80-AS102
V10P81-R05
E =
FORCE vs TRAVEL CURVE
TRAVEL (in.)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
700
600
500
400
300
200
100
V10P80-A01
V10P80-AS102
V10P81-R05
