WO2009010616A1 - Stress freezing device for photoelastic tests - Google Patents

Stress freezing device for photoelastic tests Download PDF

Info

Publication number
WO2009010616A1
WO2009010616A1 PCT/ES2008/000494 ES2008000494W WO2009010616A1 WO 2009010616 A1 WO2009010616 A1 WO 2009010616A1 ES 2008000494 W ES2008000494 W ES 2008000494W WO 2009010616 A1 WO2009010616 A1 WO 2009010616A1
Authority
WO
WIPO (PCT)
Prior art keywords
tension
specimen
equipment
photoelastic
freezing
Prior art date
Application number
PCT/ES2008/000494
Other languages
Spanish (es)
French (fr)
Inventor
Rafael Carlos Claramunt Alonso
Antonio Ros Felip
Francisco Javier SÁNCHEZ ALEJO
Original Assignee
Universidad Politécnica de Madrid
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universidad Politécnica de Madrid filed Critical Universidad Politécnica de Madrid
Publication of WO2009010616A1 publication Critical patent/WO2009010616A1/en

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/241—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet by photoelastic stress analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
    • G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
    • G09B23/06—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics
    • G09B23/08—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for statics or dynamics
    • G09B23/10—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for statics or dynamics of solid bodies
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
    • G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
    • G09B23/06—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics
    • G09B23/08—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for statics or dynamics
    • G09B23/12—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for statics or dynamics of liquids or gases

Definitions

  • the present invention relates to a device capable of creating a tensional state in a plastic specimen, whose isochromatic curves are viewed thanks to a light bulb and two polarizing filters, heating it to a certain temperature to then cool it down, so that The tensions of the test piece are permanently engraved in it. It is an invention that belongs, within the field of structural analysis, to that of photoelasticity, based on its design and development in its own knowledge and research related to the elasticity and resistance of materials.
  • Photoelasticity has been known for many years as a simple and illustrative method of studying the tensile states of specimens made of transparent or translucent glass or plastic with different shapes and subject to different mechanical stresses.
  • a photoelastic plastic material is deformed, when viewed through a polarizing filter, the tension states can be studied, as they appear as color ranges.
  • it has become an empirical method of estimating the mechanical resistance of geometric shapes, and the results obtained can be extrapolated to parts and structures of a larger scale.
  • a field where photoelasticity has found a wide application is in teaching.
  • the simplicity of its use and the immediacy of obtaining results allows students to learn the fundamental concepts of elasticity of materials and structures, since the vision and analysis of isocromatic offers a clear idea of the state of loading of a specimen with a certain geometry and solicitations.
  • the specimens are constructed in a transparent plastic, such as polycarbonate or epoxy resin, so that light can pass through them, and they can be molded or cut from an iron with the desired shape. Subsequently they can be drilled or adhere some supports from which to hang threads with the weights that will provide them with a certain state of loading. This can also be done with threaded rods or screws by pressing on certain parts of the specimens.
  • Photoelasticity is based on a physical principle called accidental birefringence, whereby certain materials, when applied to a state of charges, have a double refraction of light according to the main directions of tension.
  • a beam of diffuse and polarized light when affecting the material, is divided into two, which go to travel at different speeds through the plastic.
  • the specimen is visualized through another polarizing filter, its isocromatic strips can be seen as well as the isoclins.
  • thermosetting plastic specimens have also been known for a long time, and there are numerous specialized literature that recounts the experience, called "stress freezing method" in English.
  • Stress freezing method The general procedure consists in the heating of the specimen under small mechanical loads, until the glass transition temperature of the material is reached, at which time part of the molecular bonds are broken, notably increasing the deformation of the material, and thereby appearing the isoclin strips and isocromatic.
  • the subsequent cooling regenerates the links and freezes the state of tension or previous deformation, and with it the mentioned bands, which can be visualized once the loads have disappeared.
  • the main difficulty of this method is to have a versatile and economical equipment that allows the specimens to be subjected to multiple load states by raising the temperature in a controlled manner over a period of time, and then decreasing it in a certain way, visualizing at all times The test piece.
  • the invention allows, quickly and simply, to analyze all types of plastic specimens with multiple loading states, visualizing at all times their ischromatic and socline curves, and freezing them with a certain heating-cooling cycle.
  • the invention is a system formed by a test chamber with a load frame where a transparent thermoset plastic specimen is placed that is subjected to a tense state, and an auxiliary chamber equipped with a heating equipment that alternately insufflates the test chamber both hot air for softening the specimen, and cold air for freezing the stresses to which it is subjected.
  • the test chamber is a rigid structure closed and practicable through a door that contains a window with a polarizing filter and optionally with a quarter wave sheet. Inside the chamber there is a load frame where the specimen is located and it has jaws for anchoring it, weights hanging from wires that print a specific load to the specimen, and multiple holes where pins or pulleys can be placed Forwarding, so that the threads can affect the specimen with different angles of force.
  • the frame is provided with brackets so that threaded rods impact by pressing the specimen at certain points and the tensile threads can be tensioned by mechanical systems, such as for example traction motors, electric linear actuators, or pneumatic or hydraulic cylinders.
  • the equipment has in the auxiliary chamber a diffused light bulb located behind two windows with polarizing light filters and optionally with two quarter-wave plates, one on each side of the test tube, so that its isocromatic stripes can be visualized and Tension isocyclines while performing the photoelastic stress freeze test.
  • a heat source will also be located, which, taking fresh air from the outside, will heat it and send it to the test chamber through a grid made in the separation wall of both chambers.
  • a grid made in the separation wall of both chambers.
  • another opening in the dividing wall of the chambers which will act as return.
  • the amount of air taken from outside will be small, with the majority of the hot air flow being driven into the test chamber by the air returned to the auxiliary chamber.
  • the heating and cooling system can be a reversible heat pump, so that the heating and stress freezing process can be accelerated, and is equipped with a thermostat and a timer for process control. ,
  • the whole set is governed by a computer system that automatically controls both the stresses to which the test tube is subjected and the temperatures and test times.
  • Figure 1 Shows a system in the form of a parallelepiped (2) where both cameras are closed by the front door (1). (3) it is a window with a polarizing filter and a quarter wave blade, (4) it is a thermostat, (5) it is wheels, (6) it is a programmable timer and (7) it is locks.
  • Figure 2. Shows the same system as the one shown in the previous figure, but with the door of the test chamber (1) open, showing its interior.
  • (8) is a metal load frame, (9) it is a grid and (10) are holes.
  • Figure 3. Shows the rear part of the system, with the auxiliary chamber door (12) open.
  • (11) is a heater and (13) are fluorescent tubes.
  • Figure 4. Shows in detail the load frame (9) with a specimen fixed (15) and tensioned by a weight (17) and two traction motors (18).
  • (14) is a jaw, (16) are tension wires and (19) is a pin or pulley.
  • the system is formed by a main body (2) that contains a test chamber that is accessed through a front door (1) that is fixed with locks (7) and that contains a window (3) with a polarizing filter and a quarter wave sheet.
  • a test tube (15) attached to the frame with a jaw (14) is placed, to which a load state is applied by fixing tension wires (16) ), a weight (17) being hung on one of them and two others being tensioned by traction motors (18), pulling one of them directly and the other thread being forwarded through a pin or pulley
  • Behind the loading frame is another window (3) also equipped with a polarizing filter, a diffuser and a quarter wave sheet, which communicates the test chamber with the auxiliary chamber, which can be practiced thanks to a door (12) located in the rear.
  • fluorescent tubes (13) are placed at the height of the windows and of the specimen, which provides the light that will be polarized when passing through the window filters, allowing to see the tension strips of the charged specimen.
  • a heater (11) which takes fresh air from the outside through a grid (12) and sends it hot to the test chamber through a grid (9) made in the separation wall of both chambers, returning said air to the auxiliary chamber through holes (10) to, once reheated, return to the test chamber.
  • the set has a thermostat (4) and a programmable timer (6) that establishes the duration of the process and instructs the heater fan to act without the electric resistors, so that it blows fresh air from outside to the Ia test chamber to freeze the stresses of the specimen.
  • wheels (5) have been arranged in the lower part of all the equipment.

Abstract

The present invention concerns a device capable of creating a stress state in a plastic test subject, wherein the isochromatic curves are viewed using a light source and two polarizing filters, by heating the same to a predetermined temperature and subsequently cooling the same, in such way that the stresses on the test subject are recorded thereon permanently. This invention, within the field of structural analysis, forms part of photoelasticity, and the design and development thereof are based on relevant know-how and research related with the elasticity and resistance of materials.

Description

Título Title
Equipo de congelación de tensiones para ensayos fotoelásticόsTension freezing equipment for photoelastic tests
Objeto de Ia invenciónObject of the invention
La presente invención se refiere a un equipo capaz de crear un estado tensional en una probeta de plástico, cuyas curvas isocromáticas son visionadas gracias a un foco de luz y dos filtros polarizadores, calentándola hasta una temperatura determinada para pasar después a enfriarla, con Io que las tensiones de Ia probeta quedan grabadas en ella de manera permanente. Se trata de una invención que pertenece, dentro del campo del análisis estructural, al de Ia fotoelasticidad, apoyándose para su diseño y desarrollo en conocimientos e investigaciones propias relacionadas con Ia elasticidad y resistencia de los materiales.The present invention relates to a device capable of creating a tensional state in a plastic specimen, whose isochromatic curves are viewed thanks to a light bulb and two polarizing filters, heating it to a certain temperature to then cool it down, so that The tensions of the test piece are permanently engraved in it. It is an invention that belongs, within the field of structural analysis, to that of photoelasticity, based on its design and development in its own knowledge and research related to the elasticity and resistance of materials.
Antecedentes de Ia invenciónBackground of the invention
La fotoelasticidad es conocida desde hace muchos años como un método simple e ilustrativo de estudiar los estados tensionales de probetas fabricadas en vidrios o plásticos transparentes o translúcidos con diferentes formas y sometidas a distintas solicitaciones mecánicas. Cuando un material plástico fotoelástico se deforma, al ser visto a través de un filtro polarizador, se pueden estudiar los estados tensionales, ya que aparecen como gamas de colores. Así, se ha convertido en un método empírico de estimación de Ia resistencia mecánica de formas geométricas, pudiendo extrapolarse los resultados obtenidos a piezas y estructuras de una escala mayor.Photoelasticity has been known for many years as a simple and illustrative method of studying the tensile states of specimens made of transparent or translucent glass or plastic with different shapes and subject to different mechanical stresses. When a photoelastic plastic material is deformed, when viewed through a polarizing filter, the tension states can be studied, as they appear as color ranges. Thus, it has become an empirical method of estimating the mechanical resistance of geometric shapes, and the results obtained can be extrapolated to parts and structures of a larger scale.
Un campo donde Ia fotoelasticidad ha encontrado una amplia aplicación es en Ia docencia. La simplicidad de su uso y Ia inmediatez de Ia obtención de resultados permite a los estudiantes aprender los conceptos fundamentales de Ia elasticidad de los materiales y de las estructuras, ya que Ia visión y el análisis de las isocromáticas ofrece una idea clara del estado de carga de una probeta con una geometría y solicitaciones determinadas. Las probetas se construyen en un plástico transparente, como el policarbontato o Ia resina epoxy, para que pueda atravesarlas Ia luz, y pueden ser moldeadas o cortadas de una plancha con Ia forma deseada. Posteriormente se les pueden practicar taladros o adherir algunos soportes desde donde colgar hilos con las pesas que les proporcionarán un determinado estado de carga. Esto también puede ser realizado con vastagos roscados o tornillos presionando sobre ciertas partes de las probetas.A field where photoelasticity has found a wide application is in teaching. The simplicity of its use and the immediacy of obtaining results allows students to learn the fundamental concepts of elasticity of materials and structures, since the vision and analysis of isocromatic offers a clear idea of the state of loading of a specimen with a certain geometry and solicitations. The specimens are constructed in a transparent plastic, such as polycarbonate or epoxy resin, so that light can pass through them, and they can be molded or cut from an iron with the desired shape. Subsequently they can be drilled or adhere some supports from which to hang threads with the weights that will provide them with a certain state of loading. This can also be done with threaded rods or screws by pressing on certain parts of the specimens.
La fotoelasticidad se basa en un principio físico denominado birrefringencia accidental, por Ia cual ciertos materiales, al aplicársele un estado de cargas, presentan una doble refracción de Ia luz según las direcciones principales de tensión. Así, un haz de luz difusa y polarizada, al incidir sobre el material, se divide en dos, que pasan a viajar a distinta velocidad a través del plástico. Al ser visualizada Ia probeta a través de otro filtro polarizador, pueden verse sus franjas isocromáticas así como las isoclinas.Photoelasticity is based on a physical principle called accidental birefringence, whereby certain materials, when applied to a state of charges, have a double refraction of light according to the main directions of tension. Thus, a beam of diffuse and polarized light, when affecting the material, is divided into two, which go to travel at different speeds through the plastic. When the specimen is visualized through another polarizing filter, its isocromatic strips can be seen as well as the isoclins.
La posibilidad de congelación de las tensiones de las probetas de plásticos termoestables es también conocida desde hace tiempo, existiendo numerosa literatura especializada que relata Ia experiencia, denominada en inglés "stress freezing method". El procedimiento general consiste en el calentamiento de Ia probeta bajo pequeñas cargas mecánicas, hasta alcanzar Ia temperatura de transición vitrea del material, momento en el cual se rompen parte de los enlaces moleculares aumentando notablemente Ia deformación del material, y apareciendo con ello las franjas isoclinas e isocromáticas. El enfriamiento posterior regenera los enlaces y congela el estado de tensión o deformación previo, y con ello las mencionadas franjas, que podrán visualizarse una vez hayan desaparecido las cargas.The possibility of freezing the stresses of thermosetting plastic specimens has also been known for a long time, and there are numerous specialized literature that recounts the experience, called "stress freezing method" in English. The general procedure consists in the heating of the specimen under small mechanical loads, until the glass transition temperature of the material is reached, at which time part of the molecular bonds are broken, notably increasing the deformation of the material, and thereby appearing the isoclin strips and isocromatic. The subsequent cooling regenerates the links and freezes the state of tension or previous deformation, and with it the mentioned bands, which can be visualized once the loads have disappeared.
La dificultad principal de este método consiste en disponer de un equipo versátil y económico que permita someter a las probetas a múltiples estados de carga elevando Ia temperatura de manera controlada durante un periodo de tiempo, para luego disminuirla de una forma determinada, visualizando en todo momento Ia probeta.The main difficulty of this method is to have a versatile and economical equipment that allows the specimens to be subjected to multiple load states by raising the temperature in a controlled manner over a period of time, and then decreasing it in a certain way, visualizing at all times The test piece.
Algunos equipos y sensores para Ia medición de Ia resistencia y las tensiones existentes en materiales transparentes son protegidos mediante patente o modelo de utilidad, y se recogen principalmente en los epígrafes G01 L1/24, G01 N21/21 y G01N21/47 de Ia Clasificación Internacional de Patentes, aunque otros, sin estar protegidos por títulos de propiedad industrial, figuran en catálogos comerciales y pueden comprarse a proveedores especializados.Some equipment and sensors for measuring resistance and existing stresses in transparent materials are protected by a patent or utility model, and are mainly included in sections G01 L1 / 24, G01 N21 / 21 and G01N21 / 47 of the International Classification of Patents, although others, without being protected by industrial property titles, they are listed in commercial catalogs and can be purchased from specialized suppliers.
En ninguna de estas fuentes consultadas ha aparecido ningún equipo de congelación de tensiones para ensayos fotoelásticos como el que se describe a continuación ni ninguna solución para facilitar de forma efectiva los problemas descritos.In none of these sources consulted has any tension freezing equipment for photoelastic tests such as the one described below or any solution to effectively facilitate the problems described.
Existen algunas patentes que utilizan principios fotoelásticos como parte de un proceso para Ia determinación de las tensiones en vidrios y materiales transparentes. Por ejemplo, Ia patente europea EP0878702 describe un método y un dispositivo para medir tensiones en láminas de vidrio mediante luz dispersada, y Ia EP096746 explica cómo medir las tensiones de forma en un material transparente, tal como un acristalamiento. Estas referencias utilizan Ia fotoelasticidad como herramienta de diagnóstico, pero en ningún momento plantean Ia congelación de las mismas, y menos un equipo para lograrlo.There are some patents that use photoelastic principles as part of a process for the determination of tensions in glass and transparent materials. For example, European patent EP0878702 describes a method and a device for measuring tensions in glass sheets by scattered light, and EP096746 explains how to measure tensions in a transparent material, such as a glazing. These references use photoelasticity as a diagnostic tool, but at no time do they propose freezing them, and less equipment to achieve it.
En el estado del arte se encuentran también algunas referencias bibliográficas que describen las aplicaciones de Ia fotoelasticidad en general, y los principios de Ia congelación de tensiones en particular. DaIIy y Riley publicaron en 1978 un libro titulado "Experimental stress analysis" que explica los métodos experimentales más habituales de análisis de tensiones, dedicando un capítulo a Ia técnica de congelación de tensiones en fotoelasticidad. Loebig y Anderson publicaron en 1997 un artículo de título "Comparison of three-dimensional photoelastic stress measurement to strain gage in human cadáver fémur", donde se analizan las tensiones de flexión en un modelo fotoelástico de fémur humano. Sin embargo, tampoco en estas referencias se ha encontrado ningún antecedente similar al que se describe a continuación.In the state of the art there are also some bibliographical references that describe the applications of photoelasticity in general, and the principles of stress freezing in particular. DaIIy and Riley published in 1978 a book entitled "Experimental stress analysis" that explains the most common experimental methods of stress analysis, devoting a chapter to the technique of freezing stresses in photoelasticity. Loebig and Anderson published a title article "Comparison of three-dimensional photoelastic stress measurement to strain gage in human cadaver femur" in 1997, where bending stresses are analyzed in a photoelastic model of human femur. However, no background similar to the one described below has been found in these references.
La invención permite, de manera rápida y simple, analizar todo tipo de probetas de plástico con múltiples estados de carga, visualizando en todo momento sus curvas isocromáticas e ¡soclinas, y congelándolas con un ciclo de calentamiento-enfriamiento determinado.The invention allows, quickly and simply, to analyze all types of plastic specimens with multiple loading states, visualizing at all times their ischromatic and socline curves, and freezing them with a certain heating-cooling cycle.
Otras ventajas son Ia versatilidad de Ia instalación, Ia repetibilidad de los ensayos, el bajo coste del equipo y Ia sencillez de su montaje. Descripción de Ia invenciónOther advantages are the versatility of the installation, the repeatability of the tests, the low cost of the equipment and the simplicity of its assembly. Description of the invention
La invención es un sistema formado por una cámara de ensayos con un marco de carga donde se sitúa una probeta de plástico termoestable transparente que es sometida a un estado tensional, y una cámara auxiliar dotada de un equipo calefactor que insufla alternativamente a Ia cámara de ensayo tanto aire caliente para el reblandecimiento de Ia probeta, como aire frío para Ia congelación de las tensiones a que está sometida.The invention is a system formed by a test chamber with a load frame where a transparent thermoset plastic specimen is placed that is subjected to a tense state, and an auxiliary chamber equipped with a heating equipment that alternately insufflates the test chamber both hot air for softening the specimen, and cold air for freezing the stresses to which it is subjected.
La cámara de ensayo es una estructura rígida cerrada y practicable a través de una puerta que contiene una ventana con un filtro polarizador y opcionalmente con una lámina cuarto de onda. Dentro de Ia cámara se encuentra un marco de carga donde se sitúa Ia probeta y dispone de mordazas para el anclaje de Ia misma, pesas colgadas de hilos que imprimen una carga determinada a Ia probeta, y múltiples agujeros donde se pueden situar pasadores o poleas de reenvío, de manera que los hilos pueden incidir sobre Ia probeta con distintos ángulos de fuerza.The test chamber is a rigid structure closed and practicable through a door that contains a window with a polarizing filter and optionally with a quarter wave sheet. Inside the chamber there is a load frame where the specimen is located and it has jaws for anchoring it, weights hanging from wires that print a specific load to the specimen, and multiple holes where pins or pulleys can be placed Forwarding, so that the threads can affect the specimen with different angles of force.
Además, el marco está dotado de soportes para que vastagos roscados incidan presionando Ia probeta en puntos determinados y los hilos de tracción pueden ser tensionados por sistemas mecánicos, como por ejemplo motores de tracción, actuadores lineales eléctricos, o cilindros neumáticos o hidráulicos.In addition, the frame is provided with brackets so that threaded rods impact by pressing the specimen at certain points and the tensile threads can be tensioned by mechanical systems, such as for example traction motors, electric linear actuators, or pneumatic or hydraulic cylinders.
El equipo dispone en Ia cámara auxiliar de un foco de luz difusa situado tras dos ventanas con filtros polarizadores de luz y opcionalmente con sendas láminas de cuarto de onda, una a cada lado de Ia probeta, de manera que se pueden visualizar sus franjas isocromáticas e isoclinas de tensión mientras se realiza el ensayo fotoelástico de congelación de tensiones.The equipment has in the auxiliary chamber a diffused light bulb located behind two windows with polarizing light filters and optionally with two quarter-wave plates, one on each side of the test tube, so that its isocromatic stripes can be visualized and Tension isocyclines while performing the photoelastic stress freeze test.
En Ia cámara auxiliar se situará asimismo una fuente calorífica, que cogiendo aire fresco del exterior, Io calentará y enviará a Ia cámara de ensayos a través de una rejilla practicada en Ia pared de separación de ambas cámaras. Para permitir un calentamiento más rápido con un menor consumo energético, se practicará otra abertura en Ia pared divisoria de las cámaras, que hará las veces de retorno. Así, Ia cantidad de aire que se tome del exterior será pequeña, estando formado Ia mayor parte del flujo de aire caliente impulsado a Ia cámara de ensayos por el propio aire retornado a Ia cámara auxiliar.In the auxiliary chamber a heat source will also be located, which, taking fresh air from the outside, will heat it and send it to the test chamber through a grid made in the separation wall of both chambers. To allow faster heating with lower energy consumption, another opening in the dividing wall of the chambers, which will act as return. Thus, the amount of air taken from outside will be small, with the majority of the hot air flow being driven into the test chamber by the air returned to the auxiliary chamber.
El sistema de calefacción y de enfriamiento puede ser una bomba de calor reversible, de manera que se pueda acelerar el proceso de calentamiento y congelación de tensiones, y está dotado de un termostato y un temporizador para el control del proceso. ,The heating and cooling system can be a reversible heat pump, so that the heating and stress freezing process can be accelerated, and is equipped with a thermostat and a timer for process control. ,
Todo el conjunto está gobernado por un sistema informático que controla de manera automática tanto las tensiones a que se somete a Ia probeta como las temperaturas y los tiempos del ensayo.The whole set is governed by a computer system that automatically controls both the stresses to which the test tube is subjected and the temperatures and test times.
Descripción de los dibujosDescription of the drawings
Para complementar Ia descripción que se está realizando y con objeto de ayudar a una mejor comprensión de las características de Ia invención, se acompaña como parte integrante de dicha descripción, un juego de dibujos en donde, con carácter ilustrativo y no limitativo, se ha representado Io siguiente:To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, a set of drawings is attached as an integral part of said description, where, for illustrative and non-limiting purposes, it has been represented The following:
Figura 1.- Muestra un sistema en forma de paralelepípedo (2) donde ambas cámaras se encuentran cerradas por Ia puerta delantera (1 ). (3) es una ventana con un filtro polarizador y una lámina cuarto de onda, (4) es un termostato, (5) son unas ruedas, (6) es un temporizador programable y (7) son unos cerrojos.Figure 1.- Shows a system in the form of a parallelepiped (2) where both cameras are closed by the front door (1). (3) it is a window with a polarizing filter and a quarter wave blade, (4) it is a thermostat, (5) it is wheels, (6) it is a programmable timer and (7) it is locks.
Figura 2.- Muestra el mismo sistema que el mostrado en Ia figura anterior, pero con Ia puerta de Ia cámara de ensayos (1 ) abierta, dejando ver su interior. (8) es un marco de carga metálico, (9) es una rejilla y (10) son unos orificios.Figure 2.- Shows the same system as the one shown in the previous figure, but with the door of the test chamber (1) open, showing its interior. (8) is a metal load frame, (9) it is a grid and (10) are holes.
Figura 3.- Muestra Ia parte trasera del sistema, con Ia puerta de Ia cámara auxiliar (12) abierta. (11 ) es un calefactor y (13) son tubos fluorescentes. , Figura 4.- Muestra en detalle el marco de carga (9) con una probeta fijada (15) y tensionada por una pesa (17) y dos motores de tracción (18). (14) es una mordaza, (16) son hilos de tensión y (19) es un pasador o polea.Figure 3.- Shows the rear part of the system, with the auxiliary chamber door (12) open. (11) is a heater and (13) are fluorescent tubes. , Figure 4.- Shows in detail the load frame (9) with a specimen fixed (15) and tensioned by a weight (17) and two traction motors (18). (14) is a jaw, (16) are tension wires and (19) is a pin or pulley.
Realización preferente de Ia invenciónPreferred embodiment of the invention
La realización específica que a continuación se considera es una de entre las muchas que Ia presente invención puede adoptar. En las figuras puede observarse cómo el sistema está formado por un cuerpo principal (2) que contiene una cámara de ensayo a Ia que se accede a través de una puerta delantera (1) que es fijada con unos cerrojos (7) y que contiene una ventana (3) con un filtro polarizador y una lámina cuarto de onda.The specific embodiment that is considered below is one of the many that the present invention can adopt. In the figures it can be seen how the system is formed by a main body (2) that contains a test chamber that is accessed through a front door (1) that is fixed with locks (7) and that contains a window (3) with a polarizing filter and a quarter wave sheet.
Dentro de Ia cámara se encuentra un marco de carga metálico (8) donde se sitúa una probeta (15) fijada al marco con una mordaza (14), a Ia que se Ie aplica un estado de carga fijando en ella hilos de tensión (16), estando colgada sobre uno de ellos una pesa (17) y siendo tensionados otros dos por motores de tracción (18), tirando uno de ellos directamente y estando el otro hilo reenviado a través de un pasador o poleaInside the chamber there is a metal load frame (8) where a test tube (15) attached to the frame with a jaw (14) is placed, to which a load state is applied by fixing tension wires (16) ), a weight (17) being hung on one of them and two others being tensioned by traction motors (18), pulling one of them directly and the other thread being forwarded through a pin or pulley
(19), que puede situarse en una multitud de taladros de que dispone el marco de carga para conferirle a Ia probeta una solicitación combinada de fuerzas con distintos ángulos de incidencia.(19), which can be placed in a multitude of holes available in the loading frame to give the specimen a combined solicitation of forces with different angles of incidence.
Detrás del marco de carga se sitúa otra ventana (3) igualmente dotada de un filtro polarizador, uno difusor y una lámina cuarto de onda, que comunica Ia cámara de ensayo con Ia cámara auxiliar, que puede ser practicada gracias a una puerta (12) situada en Ia parte trasera. En ella se sitúan unos tubos fluorescentes (13) a Ia altura de las ventanas y de Ia probeta, que proporciona Ia luz que será polarizada al atravesar los filtros de las ventanas, permitiendo ver las franjas tensionales de Ia probeta cargada.Behind the loading frame is another window (3) also equipped with a polarizing filter, a diffuser and a quarter wave sheet, which communicates the test chamber with the auxiliary chamber, which can be practiced thanks to a door (12) located in the rear. In it, fluorescent tubes (13) are placed at the height of the windows and of the specimen, which provides the light that will be polarized when passing through the window filters, allowing to see the tension strips of the charged specimen.
En Ia cámara auxiliar se encuentra un calefactor (11 ), que toma aire fresco del exterior a través de una rejilla (12) y Io envía caliente a Ia cámara de ensayos a través de una rejilla (9) practicada en Ia pared de separación de ambas cámaras, retornando dicho aire a Ia cámara auxiliar a través de unos orificios (10) para, una vez recalentado, volver a Ia cámara de ensayo.In the auxiliary chamber there is a heater (11), which takes fresh air from the outside through a grid (12) and sends it hot to the test chamber through a grid (9) made in the separation wall of both chambers, returning said air to the auxiliary chamber through holes (10) to, once reheated, return to the test chamber.
Para controlar Ia temperatura, el conjunto dispone de un termostato (4) y un temporizador programable (6) que establece Ia duración del proceso y que ordena al ventilador del calefactor actuar sin las resistencias eléctricas, de modo que insufle aire fresco del exterior a Ia cámara de ensayos para congelar las tensiones de Ia probeta.To control the temperature, the set has a thermostat (4) and a programmable timer (6) that establishes the duration of the process and instructs the heater fan to act without the electric resistors, so that it blows fresh air from outside to the Ia test chamber to freeze the stresses of the specimen.
Para facilitar el transporte del conjunto y Ia apertura de Ia puerta de Ia cámara de ensayo, se han dispuesto unas ruedas (5) en Ia parte inferior de todo el equipo. To facilitate the transport of the assembly and the opening of the door of the test chamber, wheels (5) have been arranged in the lower part of all the equipment.

Claims

REIVINDICACIONES
1.- Equipo de congelación de tensiones para ensayos fotoelásticos, caracterizado por estar formado por una cámara de ensayos con un marco de carga donde se sitúa una probeta de plástico termoestable transparente que es sometida a un estado tensional, y una cámara auxiliar dotada de un equipo calefactor que insufla alternativamente a Ia cámara de ensayo tanto aire caliente para el reblandecimiento de Ia probeta, como aire frío para Ia congelación de las tensiones a que está sometida.1.- Tension freezing equipment for photoelastic tests, characterized by being formed by a test chamber with a load frame where a transparent thermostable plastic specimen is placed that is subjected to a tense state, and an auxiliary chamber equipped with a heating equipment that alternatively insufflates both the hot chamber for the softening of the specimen and the cold air for freezing the stresses to which it is subjected.
2.- Equipo de congelación de tensiones para ensayos fotoelásticos según Io descrito en Ia reivindicación 1 , caracterizado por que el equipo está dotado de un foco de luz difusa tras dos ventanas con filtros polarizadores de luz y opcionalmente con sendas láminas de cuarto de onda, una a cada lado de Ia probeta, de manera que se puedan visualizar sus franjas isocromáticas e ¡soclinas de tensión mientras se realiza el ensayo fotoelástico de congelación de tensiones.2. Tension freezing equipment for photoelastic tests according to that described in claim 1, characterized in that the equipment is provided with a diffused light source after two windows with polarizing light filters and optionally with two quarter-wave plates, one on each side of the specimen, so that its isochromatic strips and tension soclines can be visualized while the photoelastic stress freeze test is performed.
3.- Equipo de congelación de tensiones para ensayos fotoelásticos según Io descrito en Ia las reivindicaciones 1 y 2, caracterizado además por que el marco de carga donde se sitúa Ia probeta dispone de mordazas para el anclaje de Ia misma, pesas colgadas de hilos que imprimen una carga determinada a Ia probeta, y múltiples agujeros donde se puedan situar pasadores o poleas de reenvío, de manera que los hilos puedan incidir sobre Ia probeta con distintos ángulos de fuerza.3. Tension freezing equipment for photoelastic tests according to what is described in claims 1 and 2, further characterized by the fact that the load frame where the specimen is placed has jaws for anchoring it, weights hanging from threads that they print a specific load on the specimen, and multiple holes where pins or pulleys can be placed, so that the threads can influence the specimen with different force angles.
4.- Equipo de congelación de tensiones para ensayos fotoelásticos según Io descrito en Ia las reivindicaciones 1 a 3, caracterizado además por estar dotado de soportes para que vastagos roscados incidan presionando Ia probeta en puntos determinados y por que los hilos de tracción puedan ser tensionados por sistemas mecánicos, como por ejemplo motores de tracción, actuadores lineales eléctricos, o cilindros neumáticos o hidráulicos.4. Tension freezing equipment for photoelastic tests according to what is described in claims 1 to 3, further characterized by being provided with supports so that threaded rods impact by pressing the specimen at certain points and by which the tension wires can be tensioned by mechanical systems, such as traction motors, electric linear actuators, or pneumatic or hydraulic cylinders.
5.- Equipo de congelación de tensiones para ensayos fotoelásticos según Io descrito en Ia las reivindicaciones 1 a 4, caracterizado además por que el sistema de calefacción y de enfriamiento puede ser una bomba de calor reversible, de manera que se pueda acelerar el proceso de calentamiento y congelación de tensiones, y por que el equipo está dotado de un termostato y un temporizador para el control del proceso.5. Tension freezing equipment for photoelastic tests according to what is described in claims 1 to 4, further characterized in that the heating and cooling system can be a reversible heat pump, so that the process of acceleration can be accelerated. heating and freezing of tensions, and by that the equipment is equipped with a thermostat and a timer for process control.
6.- Equipo de congelación de tensiones para ensayos fotoelásticos según Io descrito en Ia las reivindicaciones 1 a 5, caracterizado además por que todo el conjunto está gobernado por un sistema informático que controla de manera automática tanto las tensiones a que se somete a Ia probeta como las temperaturas y los tiempos del ensayo. 6. Tension freezing equipment for photoelastic tests according to what is described in claims 1 to 5, further characterized in that the entire assembly is governed by a computer system that automatically controls both the tensions to which the test tube is subjected such as temperatures and test times.
PCT/ES2008/000494 2007-07-13 2008-07-11 Stress freezing device for photoelastic tests WO2009010616A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ES200701980A ES2285966B2 (en) 2007-07-13 2007-07-13 VOLTAGE FREEZING EQUIPMENT FOR PHOTOELASTIC TESTS.
ESP200701980 2007-07-13

Publications (1)

Publication Number Publication Date
WO2009010616A1 true WO2009010616A1 (en) 2009-01-22

Family

ID=38654349

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/ES2008/000494 WO2009010616A1 (en) 2007-07-13 2008-07-11 Stress freezing device for photoelastic tests

Country Status (2)

Country Link
ES (1) ES2285966B2 (en)
WO (1) WO2009010616A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105300791A (en) * 2015-12-03 2016-02-03 武汉科技大学 Test piece pressurization device for three-dimensional photoelastic stress experiment
RU2610219C1 (en) * 2015-12-22 2017-02-08 Сергей Константинович Есаулов Polarization-optical method of analyzing stress and deformation of solid material body using model made of piezo-optical material exposed to local heat flux

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2096964A (en) * 1934-05-28 1937-10-26 Max M Frocht Testing apparatus
FR840934A (en) * 1938-01-07 1939-05-08 Experimental apparatus for studying mechanics
US3373652A (en) * 1967-06-29 1968-03-19 Scott Engineering Sciences Cor Educational polariscope apparatus for determining and observing stress in photoelastic materials
US3651584A (en) * 1970-05-27 1972-03-28 Vishay Intertechnology Inc Apparatus for visually demonstrating stress patterns in a photoelastic model
DE3315761C1 (en) * 1983-04-30 1984-07-19 Dr.-Ing. A. Betz, Messtechnik GmbH, 8000 München Device for generating compressive or tensile loads on essentially flat models
US4786802A (en) * 1987-01-06 1988-11-22 Hitachi, Ltd. Apparatus for measuring photoelasticity
JP2000144239A (en) * 1998-11-02 2000-05-26 Sanseruto:Kk Heat treatment furnace

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2096964A (en) * 1934-05-28 1937-10-26 Max M Frocht Testing apparatus
FR840934A (en) * 1938-01-07 1939-05-08 Experimental apparatus for studying mechanics
US3373652A (en) * 1967-06-29 1968-03-19 Scott Engineering Sciences Cor Educational polariscope apparatus for determining and observing stress in photoelastic materials
US3651584A (en) * 1970-05-27 1972-03-28 Vishay Intertechnology Inc Apparatus for visually demonstrating stress patterns in a photoelastic model
DE3315761C1 (en) * 1983-04-30 1984-07-19 Dr.-Ing. A. Betz, Messtechnik GmbH, 8000 München Device for generating compressive or tensile loads on essentially flat models
US4786802A (en) * 1987-01-06 1988-11-22 Hitachi, Ltd. Apparatus for measuring photoelasticity
JP2000144239A (en) * 1998-11-02 2000-05-26 Sanseruto:Kk Heat treatment furnace

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
REDDY P.V. ET AL.: "A simple method to demonstrate freezing in photoelastic models", INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING EDUCATION, vol. 17, no. 2, April 1989 (1989-04-01), pages 91 - 94 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105300791A (en) * 2015-12-03 2016-02-03 武汉科技大学 Test piece pressurization device for three-dimensional photoelastic stress experiment
CN105300791B (en) * 2015-12-03 2018-05-11 武汉科技大学 A kind of test specimen pressue device for Three-dimensional Photoelastic stress test
RU2610219C1 (en) * 2015-12-22 2017-02-08 Сергей Константинович Есаулов Polarization-optical method of analyzing stress and deformation of solid material body using model made of piezo-optical material exposed to local heat flux

Also Published As

Publication number Publication date
ES2285966B2 (en) 2009-03-16
ES2285966A1 (en) 2007-11-16

Similar Documents

Publication Publication Date Title
CN203849088U (en) Shape memory performance tester
BRPI0820731A8 (en) METHOD OF EVALUATION OF THE SURFACES OF A TIRE
ES2285966B2 (en) VOLTAGE FREEZING EQUIPMENT FOR PHOTOELASTIC TESTS.
CN102788816B (en) Building environment simulation experiment system
CN206378266U (en) A kind of thermal shock test chamber
CN207850839U (en) A kind of leatherware tensile strength and degree of disturbing test device
CN218995014U (en) Metal mechanical property testing device
CN105004755A (en) Tester for testing temperature of fabric or fabric under illumination
CN210427222U (en) New material tensile properties multi-mode detection device
CN110231228A (en) Thickness is to the plate corrugation performance test apparatus and application method under stress
CN103940680B (en) Body bending detects frock
CN204241662U (en) A kind of proving installation of LED drive power
CN217385300U (en) Building door and window thermal insulation performance detection equipment
CN214584518U (en) Bidirectional tensile testing machine for thin film material
CN209385968U (en) A kind of indoor temperature and humidity environmental parameter measurement bracket
CN220708950U (en) Tensile verifying attachment of elasticity stay cord
JP4398477B2 (en) Performance comparison demonstration equipment for architectural glass
CN104089873B (en) A kind of heat aging test chamber
CN208520731U (en) One kind having the ultraviolet comprehensive experimental machine of drenching with rain of salt fog
CN208847586U (en) The soft folding performance testing device of the paper of adjustable temperature
CN206340230U (en) The teaching demonstration device of Metal Mechanic Property under condition of different temperatures can be simulated
CN208532803U (en) Microbiological detection of foods sample save set
CN206399658U (en) The timing system simulator stand of engine chain tensioner
CN206038581U (en) Cavity glass thermal insulation performance detection device
WO2014147269A1 (en) Temperature-controlled device for mixed-mode fracture tests

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 08805324

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 08805324

Country of ref document: EP

Kind code of ref document: A1