anteproyecto equipo 8
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Vr"1EqL\/IemV .o.VcontroI:1134o6
Va ;..a-.c:nLio No.contro|:10340591
- Torres Solis Manuel Alejandro No.contro|:11340716
Teacher: Julio Csar Ramirez Valenzuela
Nogales, Sonora Friday 07 of February 2014
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......23Approximate Budget.....................
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For hyra b Ab nrstricted motionis
accomplished using a oneway checkvalve that allows fluid
to bypass the dashpot fluid constriction. Nonhydraulic
dashpots may use a ratcheting gear to permit free motion in
one direction.
A dashpot is a common component in adoor closer to
prevent it from slamming shut. A spring applies force to close
the door, and the dashpot forces fluid to flow through an
orifice between reservoirs (the orifice is often adjustable),
which slows the motion of the door.
Consumer electronics often use dashpots where it is
undesirable for a media access door or control panel to
suddenly pop open when the door latch is released. The
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_energy.One
designconsideration,whendesigningor choosinga shockabsorber, is where that energy will go. In most shock
absorbers, energy is converted to heat inside the viscous
fluid. In hydraulic cylinders, the hydraulic fluid heats up, while
in air cylinders, the hot air is usually exhausted to the
atmosphere. In other types of shock absorbers, such
as electromagnetictypes, the dissipated energy can be
stored and used later. In general terms, shock absorbers help
cushion vehicles on uneven roads.
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In electro rheological fluid damper, an electric field changes the
viscosity of the oil. This principle allows semiactive dampers
application in automotive and various industries.
Other principles use magnetic field variation magneto rheological
damper which changes its fluid characteristics through
an electromagnet.
Compression of a gas, for example pneumatic shock absorbers,which can act like springs as the air pressure is building to resist
the force on it. Once the air pressure reaches the necessary
maximum, air shock absorbers will act like hydraulic shock
absorbers. In aircraft landing gear air shock absorbers may be
combined with hydraulic damping to reduce bounce.
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" :requencies is
usuallylimitedb usinga compressiblhgas as the workingfluidor mounting it with rubber bushings.
Approach to the problem
Can we design and produce a prototype of a shock absorber,
to measure the power of impact that an automobile or vehicle
creates when it crashes with a wall, using really simple
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Juscaon
The project will benefit in developing a model that has the
performance of a shock absorber that reproduces the actual
behavior as closely as possible.
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Objectives
The main objective of this project is to show the actual value
of the power of impact that an automobile transfers to a solid
object, designing and creating a complete prototype of a
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Hypothesis
By designing and creating a simple prototype that uses a
shock absorber, we could measure the amount or quantity of
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Delimit
In a time lapse of 3 months we should be testing this whole
prototype, and making sure that it shows the correct value of
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Theoretical Foundations
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Springrateia ratiouse tomeasreho\ivresistanta springis to being compressed or expanded during the
spring'sdeflection. The magnitude of the spring force
increases as deflection increases according to Hooke'sLaw.
Briefly, this can be stated as
F =
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Wheredishe wire diameter, s the spring'sshearmodulus (e.g., about 12,000,000 lbf/inz or 80 GPa for steel),
and N is the number of wraps and D is the diameter of the
coil.
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asN-m/rador- egree. inerseof springrateiscompliance, that is: if a spring has a rate of 10 N/mm, it has a
compliance of 0.1 mm/N. The stiffness (or rate) of springs in
parallel is additive, as is the compliance of springs in series.
Depending on the design and required operating
environment, any material can be used to construct a spring,
so long as the material has the required combination of
rigidity and elasticity: technically, a wooden bow is a form of
spnng.
Apiston is a component of reciprocating engines,
reciprocating pumps, gas compressors and pneumatic
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F : RX: ..where R: is a constant factor
characteristic of the spring, its stiffness.
Hooke'sequation in fact holds (to some
extent) in many other situations where an elastic body is
deformed, such as wind blowing on a tall building, a musician
plucking a string of a violin, or the filling of a party balloon. An
elastic body or material for which this equation can beassumed is said to be linearelastic or Hookean.
Hookes law is only a first order linear approximation to the
real response of springs and other elastic bodies to applied
forces. It must eventually fail once the forces exceed some
limit, since no material can be compressed beyond a certain
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nay no
- a linear map
that can be rpresente y a matrixof real numbers.In this general form, Hooke'slaw and Newton'slaws of static
equilibrium make it possible to deduce the relation between
strain and stress for complex objects in terms of intrinsic
properties of the materials it is made of. For example, one
can deduce that a homogeneous rod with uniform cross
section will behave like a simple spring when stretched, with
a stiffness3}:directly proportionalto its crosssectionarea and
inversely proportional to its length.
Hooke'slaw is named after the 17th century British
physicist Robert Hooke. He first stated this law in 1660 as
a Latin anagram, whose solution he published in 1678 as Ut
tensio, sic vis; literally translated as: "As the extension, so the
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Perfect elasticity is an approximation of the real world and
few materials remain purely elastic even after very small
deformations. In engineering, the amount of elasticity of a
material is determined by two types of material parameter.
The first type of material parameter is called
a modulus which measures the amount of force per unit area
(stress) needed to achieve a given amount of deformation.
The units of modulus are Pascals (Pa) or pounds of force per
square inch (psi, also lbf/inz). A higher modulus typically
indicates that the material is harder to deform. The second
type of parameter measures the elastic limit. The limit can
be a stress beyond which the material is no longer elastic or a
deformation beyond which elasticity is lost.
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dampe nA AV - A _.,reeof freedom,
the elastic element incorporates both stiffness and damping.
The project presented from their calculations using MATLAB
defining a desired movement pattern of behavior that can be
implemented or adapted for various applications.
This project is perfect to implement models that faithfully
reproduce the behavior of each component as an essential
tool to reduce the power of impact.
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lrvingfa , ...~-r;:ts.Newnes.pp.
13-15.
Treloar, L. R. G. (1975). The Physics of Rubber Elasticity.
Oxford: Clarendon Press. p. 2.
White, Lynn Jr. (1966). Medieval Technology and Social
Change. New York: Oxford Univ. Press. ISBN 049-500266-
O., p.126127
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