DE102014200954A1 - Detection of local mechanical loads - Google Patents

Abstract

The invention relates to a method for detecting local mechanical loads which act on a component (2), in particular vehicle component, formed of fiber composite material, wherein at least one optical fiber (3) forming a fiber optic sensor is arranged in at least one section of the component (2) , and wherein the local mechanical loads are detected by means of the optical waveguide (3).

Description

The invention relates to a method and a system for detecting local mechanical loads, which act on a component formed from fiber composite material, in particular vehicle component.

Furthermore, the invention relates to a component, in particular vehicle component, of a fiber composite material.

It is known to design vehicle components, which are made of a fiber composite material, by means of a simulation and to try out in an experiment. Vehicle components made of a fiber composite material and in the form of shell components generally have the same wall thickness and the same layer structure over the entire component surface, although experience has shown that the mechanical stresses acting on such a vehicle component are very different.

The simulation of vehicle components made of a fiber composite material is still in a development stage, especially since there is a lack of feedback from users of appropriately equipped vehicles and long-term experience due to the fairly recent use of vehicle components made of a fiber composite material. In order to take no risk, therefore, vehicle components made of a fiber composite material are conventionally oversized as a rule in order to give these vehicle components an adequate stability and durability. However, this is associated with high costs and an increase in the weight of a vehicle equipped with such vehicle components.

Weaknesses in vehicle components made from a fiber composite material, which are not recognized in conventional simulations and tests, can prove costly in future use.

The object of the invention is to optimize the production of components, in particular vehicle components, from fiber composite material by taking into account local mechanical stresses acting on the components.

This object is achieved by a method having the features according to claim 1, a system having the features according to claim 7 and a component having the features according to claim 8. Advantageous embodiments are given in the dependent claims, which in each case taken alone or in different combinations with each other can represent an aspect of the invention.

With claim 1, a method for detecting on a formed of a fiber composite component, in particular vehicle component, acting local mechanical loads is proposed, wherein at least one fiber optic sensor forming optical waveguide is disposed in at least a portion of the component, and wherein the local mechanical loads of the optical waveguide are detected.

According to the invention, at least one optical waveguide is integrated in a component made of a fiber composite material and used as a fiber optic sensor. By acting on such a component local mechanical loads, the component can be plastically or elastically deformed. Such a deformation of a component acts on the optical waveguide arranged in the component, as a result of which the optical waveguide is likewise elastically or plastically deformed. These deformations of the optical waveguide can be detected via the optical waveguide designed as a fiber-optic sensor. From the detected deformations of the optical waveguide can be deduced the respectively acting on the component local mechanical stress. The knowledge about the extent and the place of action of local mechanical loads acting on a component made of a fiber composite material can be taken into account in the design of such components or their production. As a result, for example, more mechanically loaded sections of a component made of a fiber composite material can be provided with a greater wall thickness than sections of the component which are exposed to lower mechanical loads. The number of fiber layers and the alignment of fibers of fiber layers can be varied in order to be able to optimally adapt a component made of a fiber composite material to the respective application. It is not necessary to give the entire component a correspondingly large and uniform wall thickness, as is conventional. Consequently, according to the invention, components which are optimally adapted to the respective application can be produced with regard to their weight and their stability, which has a favorable effect on the manufacturing costs associated therewith and can be accompanied by a weight saving.

The non-destructive detection according to the invention of the local mechanical loads acting on a component constructed as a vehicle component from a fiber composite material can be carried out as dynamic detection during driving operation of a suitably equipped vehicle or on a test stand. The recorded local mechanical loads can be compared with conventionally applied load simulations to improve the load simulations. This allows an optimal design of components made of a fiber composite material.

The optical waveguide may be formed as a commercially available glass fiber. The light pulse is preferably a laser light pulse. In the context of the invention, the term "light" is to be understood in general electromagnetic radiation whose frequency may be within or outside the spectrum of visible light.

According to an advantageous embodiment, the optical waveguide is arranged in the component such that at least one end of the optical waveguide is accessible from the outside accessible or accessible feasible on the component, wherein on the component accessible from the outside or made accessible end of the optical waveguide at least one Light pulse is coupled during the action of the local mechanical stresses on the component in the optical waveguide, and wherein one of the accessible arranged or made accessible end or other on the component accessible from the outside or accessible feasible arranged end of the optical waveguide light emerging from the optical waveguide recorded and evaluated.

In order to be able to couple at least one light pulse into the optical waveguide, the optical waveguide is arranged in the component in such a way that at least one end of the optical waveguide is arranged accessible or accessible from the outside on the finished component. That this end is arranged accessible or accessible feasible on the finished component, to mean that it is physically and visually accessible or accessible feasible arranged on the finished component. The end can be arranged accessible or accessible such that it can be connected to an optical adapter, via which at least the light pulse can be coupled into the waveguide.

The coupled into the optical waveguide light pulse is influenced by an elastic or plastic deformation of the optical waveguide, for example, at least partially reflected. The resulting change in the light pulse can be detected and evaluated by detecting an end of the light waveguide emerging from the accessible or accessible end or another end of the optical waveguide that is accessible or accessible from the outside. As a result, an elastic or plastic deformation of the optical waveguide or of the component surrounding it can be detected with millimeter precision over the entire length of the optical waveguide.

In the context of the invention, both ends of the optical waveguide can be arranged accessible or accessible feasible on the finished component. The light emerging from the optical waveguide can exit from the same end of the optical waveguide into which the light pulse has been coupled, or it can emerge from the respectively other end of the optical waveguide.

According to a further advantageous embodiment, the arrangement of the optical waveguide in the component takes place in that the optical waveguide is arranged on a fiber arrangement of the fiber composite material and then the composite of fiber array and optical waveguide is impregnated with a matrix material. The optical waveguide is firmly connected by the impregnation with the fiber assembly and thus integrated into the component. The fiber arrangement can be designed in one, two or more layers. In addition, the fiber assembly may be formed as a scrim, knitted fabric, or the like. The matrix material may comprise at least a hardener and a resin. After impregnation, the impregnated composite of fiber assembly and optical fiber can be brought by means of a pressing tool in a desired shape and cure in this position.

According to a further advantageous embodiment, the optical waveguide is at least partially connected before impregnation by means of an adhesive technique or a textile technique with the fiber assembly or the optical waveguide is at least partially arranged loosely on or in the fiber assembly prior to impregnation. The optical waveguide can be woven, for example, with the fiber arrangement. The optical waveguide can be arranged at least partially between fiber layers of the fiber arrangement. The optical waveguide can first be connected to a support grid, after which the composite of optical waveguide and support grid can be arranged on the fiber arrangement. Which connection technology is chosen depends on the respective circumstances and requirements.

A further advantageous embodiment provides that the optical waveguide is at least partially arranged in a straight line or meander shape in the component. For example, the optical waveguide can be arranged in regions of the component which are usually subjected to particularly high stress, for which purpose its respective shape can be adapted to typical lines of force which run in the component.

According to a further advantageous embodiment, the optical waveguide is arranged extending in a partial region of the component or substantially in the entire component. For example, the optical waveguide can be arranged exclusively in such sections of the component, which experience has shown that the use of the component is subject to particularly high mechanical stresses.

• – wenigstens einen derart in dem Bauteil anordbaren, einen faseroptischen Sensor ausbildenden Lichtwellenleiter, dass wenigstens ein Ende des Lichtwellenleiters von außen zugänglich oder zugänglich machbar an dem Bauteil angeordnet ist;
• – wenigstens eine Einrichtung zum Erzeugen von Lichtimpulsen,
• – wenigstens eine Einrichtung zum Einkoppeln der Lichtimpulse in das an dem Bauteil von außen zugänglich angeordnete bzw. zugänglich gemachte Ende des Lichtwellenleiters,
• – wenigstens eine Einrichtung zum Erfassen eines aus dem zugänglich angeordneten bzw. zugänglich gemachten Ende oder einem anderen an dem Bauteil von außen zugänglich angeordneten oder zugänglich gemachten Ende des Lichtwellenleiters aus dem Lichtwellenleiter austretenden Lichts, und
• – wenigstens eine elektronische Auswertungseinrichtung, wobei die elektronische Auswertungseinrichtung kommunikationstechnisch zumindest mit der Einrichtung zum Erzeugen von Lichtimpulsen und der Einrichtung zum Erfassen des aus dem Lichtwellenleiter austretenden Lichts verbunden ist und zum Erfassen und Auswerten des Lichts eingerichtet ist.

With claim 7, a system for detecting on a formed of a fiber composite component, in particular vehicle component, acting local mechanical loads is proposed, comprising

• - At least one such in the component can be arranged, forming a fiber optic sensor optical waveguide that at least one end of the optical waveguide is accessible from the outside accessible or accessible feasible on the component;
• At least one device for generating light pulses,
• At least one device for coupling the light pulses into the end of the optical waveguide which is accessible from the outside or made accessible on the component,
• At least one device for detecting a light emitted from the accessible or accessible end or another end of the optical waveguide that is accessible from the outside and made available to the component from the optical waveguide, and
• - At least one electronic evaluation device, wherein the electronic evaluation device is communication technology at least connected to the means for generating light pulses and the means for detecting the light emerging from the optical fiber light and is adapted to detect and evaluate the light.

With this system, the advantages mentioned above with respect to the method are connected accordingly. The means for generating light pulses may be configured to generate laser light pulses. The device for coupling light pulses into the end of the optical waveguide that is accessible or accessible from the outside on the component can comprise an adapter which can be coupled optically to the end of the optical waveguide. Such an optical adapter can also serve as a device for decoupling a light emerging from the accessible or accessible end or another end of the optical waveguide that is accessible from the outside and made accessible to the component from the optical waveguide.

The electronic evaluation device can be used to control the device for generating light pulses and can receive information from the device for detecting the light emerging from the optical waveguide and evaluate this information. For this purpose, the electronic evaluation device may have a computer unit, for example a microprocessor.

With claim 8, a component, in particular vehicle component, proposed from a fiber composite material, characterized by at least one integrated in the fiber composite material, a fiber optic sensor forming optical waveguide, wherein at least one end of the optical waveguide is accessible from the outside or accessible feasible arranged on the component.

With this component, the above-mentioned method is feasible, so that with the component, the advantages mentioned above with respect to the method are connected accordingly.

According to an advantageous embodiment of the optical waveguide is at least partially arranged in a straight line or meandering.

According to a further advantageous embodiment, the optical waveguide is arranged extending in a partial region of the component or substantially in the entire component.

According to a further advantageous embodiment, the optical waveguide is arranged at least partially on and / or in a fiber arrangement of the fiber composite material.

Furthermore, it is considered advantageous if the optical waveguide is at least partially connected to the fiber arrangement by means of a textile technique and / or an adhesive technique.

Further details, features and advantages of the invention will become apparent from the following description and the figure. It shows:

1 a schematic representation of an embodiment of an inventive system and an inventive component.

1 shows a schematic representation of an embodiment of a system according to the invention 1 for detecting a component formed from a fiber composite material 2 acting in the form of a vehicle component local mechanical loads.

The system 1 includes such in the component 2 arranged, forming a fiber optic sensor optical waveguide 3 that one end 4 of the optical fiber 3 accessible from outside on the component 2 is arranged.

The system 1 further includes a device 5 for generating light pulses and a device 6 for coupling the light pulses into that on the component 2 accessible from the outside arranged end 4 of the optical fiber 3 , The last mentioned device 6 includes an optical fiber 7 , which at both ends in each case an adapter 8th has, over which the optical waveguide 6 on the one hand with the end 4 of the optical fiber 3 and on the other hand with one the device 5 including structural unit 9 connected is.

Furthermore, the system includes 1 An institution 10 for detecting an accessible from the end arranged 4 of the optical fiber 3 from the optical fiber 3 leaking light, including the device 10 over the optical fiber 7 with the end 4 of the optical fiber 3 connected is.

Furthermore, the system includes 1 an electronic evaluation device 11 , the communication technology with the device 5 for generating light pulses and the device 10 for detecting the from the optical fiber 3 Exiting light is connected and is set up for detecting and evaluating the light.

The optical fiber 3 is meandering and essentially in the entire component 2 arranged extending.

LIST OF REFERENCE NUMBERS

1

system

2

component

3

optical fiber

4

The End

5

Facility

6

Facility

7

optical fiber

8th

adapter

9

unit

10

Facility

11

electronic evaluation device

Claims (12)

Method for detecting local mechanical stresses acting on a component made of fiber composite material ( 2 ), in particular vehicle component, wherein at least one fiber optic sensor forming optical fiber ( 3 ) in at least a portion of the component ( 2 ), and wherein the local mechanical loads by means of the optical waveguide ( 3 ). Method according to Claim 1, characterized in that the optical waveguide ( 3 ) in the component ( 2 ) is arranged, that at least one end ( 4 ) of the optical waveguide ( 3 ) accessible from outside or accessible to the component ( 2 ), wherein over the on the component ( 2 ) accessible or accessible from the outside ( 4 ) of the optical waveguide ( 3 ) at least one light pulse during the action of the local mechanical stresses on the component in the optical waveguide ( 3 ), and wherein an end made accessible or accessible ( 4 ) or another on the component ( 2 ) accessible from the outside or accessible from the end ( 4 ) of the optical waveguide ( 3 ) from the optical waveguide ( 3 ) light is detected and evaluated. Method according to Claim 1 or 2, characterized in that the arrangement of the optical waveguide ( 3 ) in the component ( 2 ) is effected in that the optical waveguide ( 3 ) is arranged on a fiber arrangement of the fiber composite material and then the composite of fiber arrangement and optical waveguide ( 3 ) is impregnated with a matrix material. Method according to Claim 3, characterized in that the optical waveguide ( 3 ) before the impregnation at least partially connected by means of an adhesive technique or a textile technique with the fiber assembly or that the optical waveguide ( 3 ) is placed at least partially loosely on or in the fiber assembly prior to impregnation. Method according to one of claims 1 to 4, characterized in that the optical waveguide ( 3 ) at least partially rectilinear or meandering in the component ( 2 ) is arranged. Method according to one of claims 1 to 5, characterized in that the optical waveguide ( 3 ) in a partial region of the component ( 2 ) or substantially in the entire component ( 2 ) is arranged extending. System ( 1 ) for detecting local mechanical loads on a component made of fiber composite material ( 2 ), in particular vehicle component, acting, comprising - at least one in at least a portion of the component ( 2 ), an optical fiber forming a fiber optic sensor ( 3 ) that at least one end ( 4 ) of the optical waveguide ( 3 ) accessible from outside or accessible to the component ( 2 ) is arranged; - at least one institution ( 5 ) for generating light pulses, - at least one device ( 6 ) for coupling the light pulses into the component ( 2 ) accessible or accessible from the outside ( 4 ) of the optical waveguide ( 3 ), - at least one institution ( 10 ) for detecting a arranged from the accessible or accessible end ( 4 ) or another on the component ( 2 ) arranged accessible or accessible from the outside ( 4 ) of the optical waveguide ( 3 ) from the optical waveguide ( 3 ) emitted light, and - at least one electronic evaluation device ( 11 ), wherein the electronic evaluation device ( 11 ) communication technology at least with the device ( 5 ) for generating light pulses and the device ( 10 ) for detecting the out of the optical waveguide ( 3 ) emitted light and is set up for detecting and evaluating the light. Component ( 2 ), in particular a vehicle component, of a fiber composite material, characterized by at least one optical waveguide which is integrated in the fiber composite material and forms a fiber-optic sensor ( 3 ), wherein at least one end ( 4 ) of the optical waveguide ( 3 ) accessible from outside or accessible to the component ( 2 ) is arranged. Component ( 2 ) according to claim 8, characterized in that the optical waveguide ( 3 ) is arranged at least partially rectilinear or meandering. Component ( 2 ) according to claim 8 or 9, characterized in that the optical waveguide ( 3 ) in a partial region of the component ( 2 ) or substantially in the entire component ( 2 ) is arranged extending. Component ( 2 ) according to one of claims 8 to 10, characterized in that the optical waveguide ( 3 ) is arranged at least partially on and / or in a fiber arrangement of the fiber composite material. Component ( 2 ) according to claim 11, characterized in that the optical waveguide ( 3 ) is at least partially connected by means of a textile technique and / or an adhesive technique with the fiber assembly.

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