Device And Method For Reducing A Stress Concentration At An Edge Of A Laminated Composite Material

Abstract

A device for reducing a stress concentration at an edge of a laminated composite material has an optical element, an actuator element, and a receptacle space for a first component of a laminated composite material which can be or is connected to a second component via a contact face and has an edge element above the contact face. The optical element defines a focus face for laser radiation for vaporizing laminated composite material. The actuator element is designed to move the optical element around a first component arranged in the receptacle space. and orients the optical element in such a way that an angle, including the first component, between the contact face and the focus face is smaller than 90. The angle is selected such that after vaporization of the laminated composite material at the focus face the stress concentration at the edge element is reduced under load.

Claims

1. A device for reducing a stress concentration at an edge of a laminated composite material, wherein the device comprises: an optical element; an actuator element; and a receptacle space for a first component composed of a laminated composite material, wherein the first component can be or is connected to a second component via a contact face and has an edge element above the contact face, wherein the optical element defines a focus face for laser radiation for vaporizing laminated composite material, wherein the actuator element is configured to move the optical element around a first component arranged in the receptacle space, wherein the actuator element orients the optical element with an edge element in such a way that an angle, including the first component, between the contact face and the focus face is smaller than 90, and wherein the angle is selected such that after vaporization of the laminated composite material at the focus face the stress concentration at the edge element is reduced under load.

2. The device according to claim 1, wherein the actuator element is a robot arm.

3. The device according to claim 1, wherein the optical element has the focus face for radiation of a high-energy laser system.

4. The device according to claim 3, wherein the optical element is connected to the high-energy laser system by an optical fibre, and wherein the optical fibre guides the laser light emitted by the high-energy laser system to the optical element.

5. The device according to claim 1, wherein the device comprises a control unit configured for transmitting control signals to the actuator element.

6. A method for reducing a stress concentration at an edge of a laminated composite material, wherein the method comprises: a) providing a first component made of laminated composite material which can be or is connected to a second component via a contact face, wherein the first component has an edge element above the contact face, b) moving an optical element with an actuator element with respect to the edge element, with the result that the edge element is arranged in a focus face of the optical element, c) orienting the optical element by the actuator element, with the result that an angle, including the first component, between the contact face and the focus face, is less than 90, d) eroding the composite material, arranged in the focus face, of the edge element by laser radiation directed through the optical element, wherein the angle is selected such that after step d) a stress concentration under load at the edge element is less than before step d).

7. The method according to claim 6, wherein the method further comprises: e) moving the optical element by the actuator element along the edge element while step d) is being executed.

8. The method according to claim 6, wherein the method comprises, before step c): f) determining the angle by a simulation of the stress concentration at the first component.

9. A composite component manufactured by the method according to claim 6, wherein the composite component comprises: a first component which comprises a laminated composite material with at least one layer; wherein the first component can be connected to a second component via a contact face, wherein the first component has an edge element above the contact face, wherein the edge element comprises a surface element which forms, with respect to the contact face, an angle, including the first component, of less than 90, wherein at least one layer has a layer surface element which is oriented in parallel with the surface element, and wherein the layer surface element adjoins at least one other layer of the first component and forms at least part of the surface element.

10. The composite component according to claim 9, wherein the surface element is planar.

11. The composite component according to claim 9, wherein the composite component has a second component which is connected to the first component via the contact face.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the text which follows, the invention will be described on the basis of an exemplary embodiment by means of the appended drawing, in which:

[0027] FIG. 1 shows a schematic illustration of the device during the processing of an edge element of a stringer;

[0028] FIG. 2 shows a schematic illustration of an overlapping region of a first component with a second component, wherein the first component is embodied as a stringer;

[0029] FIG. 3 shows a schematic cross-sectional illustration of an overlapping region of two components and the stress concentration therein;

[0030] FIGS. 4a and 4b show a schematic cross-sectional illustration of a device with an overlapping region of two components and the stress concentration therein; and

[0031] FIG. 5 shows a schematic illustration of a flowchart of the method.

DETAILED DESCRIPTION

[0032] The device is referred to below in its entirety by the reference symbol 1, as illustrated in FIG. 1. The device 1 comprises an optical element 2, an actuator element 3, a receptacle space 4, a high-energy laser system 10 and a control device 12.

[0033] The optical system 2 is connected to the actuator element 3. The actuator element 3 can be embodied here as a robot arm. With the actuator element 3 it is possible to position the optical element 2 at a wide variety of locations in each orientation.

[0034] The optical element 2 furthermore defines a focus face 9 in which laser light, which is directed through the optical element 2, is focussed. The laser light is generated here in the high-energy laser system 10 and directed to the optical element 2 by means of an optical fibre 11 which connects the high-energy laser system 10 to the optical element 2.

[0035] The focus face 9 defines, through the focussing of the laser light, a face in which high temperatures occur if laser light is guided through the optical element 2. A composite material can be vaporized on the focus face 9 by means of the high temperatures. In this context, the composite material is vaporized in the region of the focus face 9, and a face is produced in the composite material which is parallel to the focus face 9. The angle of the focus face 9 therefore also determines the angle of the resulting surface which remains after the vaporization of the composite material.

[0036] A first component 5, which is embodied as a stringer in this exemplary embodiment, is illustrated in FIG. 1 here. The first component 5 is connected to a second component 7 via a contact face 6. The contact face 6 is arranged between the first component 5 and the second component 7 here. The first component 5 has an edge element 8, 8 above the contact face 6. Part of the edge face of the edge element, said part denoted by the reference number 8, is embodied as a ramp. Another part, denoted by the reference number 8, has a stepped shape. The focus face 9 of the optical element 2 is arranged between the edge element regions 8 and 8 in FIG. 1. The focus face 9 vaporizes part of the edge element region 8 in FIG. 1 and converts this region 8 into a surface element 30 which has, with the contact face 6, an angle of less than 90 which includes the first component 5. This angle, which the surface element 30 has at the edge element 8, corresponds to the angle which the focus face forms with the contact face 6.

[0037] The optical element 2 is moved along the edge element 8 by means of the actuator element 3. For this purpose, the actuator element 3 has, in this exemplary embodiment, a rail element 25 on which a movement element 26 is arranged. The movement element 26 can move along the rail 25 independently.

[0038] In an alternative embodiment, the actuator element 3 can be arranged above or below the receptacle space 4 (not illustrated). In this context, the actuator element 3 can be mounted rotatably, with the result that the optical element 2 can be made to approach the first component 5 from all sides and can be oriented therewith.

[0039] In a further alternative embodiment, the actuator element 3 can be arranged on a mobile platform (not illustrated), wherein the mobile platform can be moved independently of the receptacle space 4. In this way, the optical element 2 can be arranged flexibly with respect to the first component 5.

[0040] The actuator element 3 can be controlled by means of the control unit 12 via a signal cable 13. For this purpose, the control unit 12 can be designed to receive a predefined angle for the optical element 2 with respect to the first component 5. This predefined angle can be determined e.g. from a simulation of the voltage profile at the first component 5. Furthermore, the control element 12 can output a triggering signal for the high-energy laser system 10.

[0041] An example of the simulation of a stress concentration distribution at the first component 5 is illustrated in FIG. 2. The arrow 27 shows here a shearing movement which acts on the first component 5. Since the first component 5 is connected to the second component 7 via the contact face 6, stresses arise between the first component 5 and the second component 7. This stress is plotted in the lower region of FIG. 2. In this context, the X axis and Y axis are the surface coordinates of the contact face and the vertical axis is the magnitude of the stress t at a specific point on the surface. The plane 18 indicates here the magnitude of the stress concentration of the surface. Significant increases in stress can be seen at the ends 16 and 17 in FIG. 2. The surface 18 runs here in a curved fashion, with the result that a high stress concentration is present particularly at the edge regions and corner regions of the first component 5.

[0042] This high stress concentration can cause individual layers of the composite material from which the first component can be formed to become detached, as a result of which the connection between the first component 5 and the second component 7 is weakened. The entire composite component therefore becomes weaker.

[0043] An example of the connection between a first component 5, which is illustrated as a shell component or as a doubler, and a second component 7 is illustrated in FIG. 3. The contact face 6 is arranged here between the first component 5 and the second component 7. The arrows 28 and 29 show here tensile forces which are arranged parallel with respect to the contact face 6. The resulting stress between the two components is illustrated in the diagram arranged under the components. Just one dimension is illustrated in FIG. 3 here. The stress curve 15 is increased here at the ends 13 and 14 of the two components. The stresses between the two components drop away abruptly outside the contact face 6.

[0044] FIG. 4a illustrates how an edge element 8 is processed from an optical element 2 by means of laser radiation by means of a device 1 according to the invention. The edge element 8 is partially converted into a ramp shape here. This is apparent from the stress diagram arranged underneath the second component 7. The stress concentration at the end 13 of the stress curve 15 is lower than the stress concentration at the end 14. Since the processing of the edge element 8 is not yet concluded, the stress concentration at the end 13 is still higher than at the minimum value of the curve 15.

[0045] FIG. 4b shows a composite material 31 which has surface elements 30 at the edge elements 8. The surface elements 30 are planar. That is to say the laminate layers 19, 20, 21 of the first component 5 have layer end faces 22, 23, 24 which are planar and which together form the surface element 30. The layer end faces 22, 23, 24 therefore have the same angle with respect to the contact face 6 as the surface element 30. The stress diagram which is arranged underneath the second component 7 is a stress curve 15 which has an extremely low stress concentration at the ends 13 and 14. Stress peaks are no longer present.

[0046] FIG. 5 shows a diagram of a method 100 according to the invention. In a first step 101, a first component composed of laminated composite material is made available here. The first component is connected to a second component via a contact face here and has an edge element above the contact face. The first component can be made available here in a receptacle space of a device according to the invention.

[0047] In a second step 102, an optical element is moved with respect to the edge element. The movement of the optical element can be carried out here with an actuator element. Furthermore, the edge element is arranged, by virtue of the movement of the optical element, into a focus face which is defined by the optical element. In this way, laser radiation which is directed through the optical element can impinge on the focus face. As a result, composite material on the edge element can be vaporized.

[0048] In a further step 106, a simulation can be used to calculate an angle for the edge element on the first component, which angle brings about a reduction in the stress concentration at the edge element of the first component in comparison with the original angle at the edge element. This angle can accordingly also be referred to as an angle of change. Furthermore, this angle is a predefined angle.

[0049] The angle has here a value between 0 and 90 and is measured in such a way that it includes the first component and is determined between a surface element of the processed edge element and the contact face.

[0050] The optical element can be oriented in step 103 by means of the actuator element in such a way that the focus face assumes the predefined angle in comparison with the contact face.

[0051] Then, in a step 104 the composite material of the edge element which is arranged in the focus face can be eroded. The erosion is carried out by introducing laser radiation into the optical element. The laser radiation is focused in the focus face by means of the optical element. A high temperature is therefore suddenly generated in the focus face by means of the laser radiation. The composite material is vaporized by this high temperature. In this way, a surface element can be generated which is planar over the laminated layers of the composite material and forms, with the contact face, an angle which is less than 90. This face is furthermore smooth and runs continuously between the surface of the first component pointing away from the contact face and the surface of the second component adjoining the contact face.

[0052] While the step 104 is being carried out, the optical element can be moved along the edge element with the actuator element with a step 105. The optical element can therefore be moved along the edge element, with the result that the focus face is also moved along the edge element. In this way, a face on the edge element can be processed which is larger than the focus face. The processing can take place without interruption.

[0053] Furthermore, the angle of the optical element can be varied during the movement along the edge element, in order to obtain a minimum stress concentration at each position of the edge element.

[0054] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, the terms a or one do not exclude a plural number, and the term or means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.