anteproyecto equipo 8

8/12/2019 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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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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