WO2020016317A1

WO2020016317A1 - Method and device for the non-destructive determining of local mechanical properties of components made of non-homogeneous materials.

Info

Publication number: WO2020016317A1
Application number: PCT/EP2019/069279
Authority: WO
Inventors: Philipp MORITZ
Original assignee: Fachhochschule Aachen
Priority date: 2018-07-17
Filing date: 2019-07-17
Publication date: 2020-01-23
Also published as: EP3824283A1; DE102018005635A1

Abstract

The invention relates to a method and a device for the non-destructive determining of local mechanical properties of a component, preferably an elongated component made of non-homogeneous materials or a non-homogeneous material distribution, wherein the component is exposed to a mechanical loading which deforms the component and the deformation of the component is detected in a camera-based manner at a plurality of defined measuring points or measuring sections, and the local deformation of the component is determined from the camera data and the local mechanical property is calculated from the local deformation.

Description

Method and device for the non-destructive determination of local mechanical properties of components made of inhomogeneous materials

The invention relates to a method and a device for the non-destructive determination of local mechanical properties of a component, preferably an elongated component, made of inhomogeneous materials.

Typical examples of components with pronounced anisotropic and at the same time inhomogeneous properties are those made from recycled plastics,

Fiber composite materials and in particular organic, preferably naturally grown materials, such as wood and bamboo cane. The local mechanical properties of components made from such materials vary widely within the component. Local mechanical properties are understood to mean those that differ at different locations on the component, in particular with regard to their amount / value.

In the case of recycled plastics, they depend on the starting materials.

Degree of mixing, mutual compatibility and properties and

Composition of the starting materials have a complex interaction on the mechanical properties of the material and thus also on the component made from it. In industrial processing, the inhomogeneity of the properties results in high safety factors for component design with these materials. Applications with high quality requirements and corresponding price and sales potential are usually excluded.

The mechanical properties of components made of fiber composite materials depend on the fiber distribution, the degree of wetting, the properties of the components, the thermal process control and many other factors. The use as a lightweight material places special demands on the methods of design and a stable quality control. The quality control of the

As a result, the manufacturing processes of industrially manufactured fiber composite components are complex and a decisive cost factor. With organic, preferably naturally grown components or semi-finished products such as bamboo cane, the pronounced inhomogeneity is a result of the natural growth process.

The method of classic proof of strength in component design is only of limited suitability for lightweight construction with inhomogeneous materials. The invention is intended to improve quality assurance in the manufacture of components and semi-finished products, e.g. for lightweight applications. It is intended to enable reliable prediction of the deformation behavior and reliable strength monitoring.

State of the art in the production of components from recycled plastics is the design of the entire component assuming homogeneous

mechanical properties. The range of mechanical properties of the material varies in different areas of the component. For reliable design, the lower limit of the mechanical properties is used as a reference and calculation basis.

State of the art in the production control of fiber composite components for

Lightweight applications is the monitoring of the manufacturing process. The

Homogeneity of the matrix and fiber orientation are determined using different technologies. The process-related imaging processes, for example, control the orientation and number of fibers in the individual layers of a layered structure of the reinforcing fibers.

The stable control of the cross-linking depends on the matrix material. Sensors are integrated into the infusion systems and / or tools, and pressure and temperature profiles are monitored. The properties of the laminate quality, such as pore content, fiber volume content, fiber alignment and undulation, cracks and other matrix inhomogeneities, are compared with the specifications for the respective component on component samples using various imaging methods.

The prediction of the influence of individual structural deviations on the resulting component behavior is based on highly complex modeling.

In order to improve the model quality, the deformation behavior of prototypes and sample components with measurement systems is determined on the basis of image correlation. With wood or bamboo as an organic lightweight construction material or directly as a component, there is no monitoring of the manufacturing process. Nevertheless, the procedure for determining the mechanical properties of wood-based materials is comparable. The orientation and density distribution of the fiber structure are determined using X-ray systems or ultrasound methods. The result of this investigation is converted into a theoretical strength. Other important influencing factors in this evaluation are moisture and in particular the type of wood.

The methods of data evaluation and the basics of modeling to predict deformation and failure behavior are all in one

extensive standards for the industrial use of wood standardized. The standards were based on experimental tests with

different sample geometries, types of wood and under different external influences. In principle, the previous method is high

Safety factors associated, for example resulting from the larger component volume compared to the sample. The consequence of the safety factors is an oversizing of wooden components, which prevents their use as a lightweight material. Bamboo is a grass and so far not comparable standardized. The industrial use of bamboo cane is limited to the isolated fibers of the plant as an additive in plastics or solid materials, which are composed of parts of the cane and have comparable properties to beams or slats made of solid wood. A comparable to wood-based materials

There is standardization for bamboo materials or naturally grown ones

Bamboo cane not.

The common disadvantage of the current state of the art in the quality control of inhomogeneous materials for industrial production results from the methodology when evaluating the results. The material testing and the

The design of components made from these materials are based on the processes for metallic materials or have been derived from them. The basis is the principle of the reference voltage. The mechanical properties of a material are determined using standardized sample geometries. The mechanical properties determined in this way then become dependent on

Component geometry and load introduction resulting stresses in the component or

Semi-finished products compared. In the case of inhomogeneous materials, the determined comparison value is formed by the areas with low mechanical properties. The size determined in this way is then determined by factors that are larger than the sample

Take component volume and / or influences resulting from production into account, further reduced. The previously described method leads to a significant oversizing of the components or to an increased reject rate.

The invention has the task of quality assurance in the manufacture of

To improve products with components or sheet products made of materials with inhomogeneous mechanical properties, in particular by knowing the local properties, that is to say the different properties at different locations of the same component. The invention also has the task of enabling a digitally simulated construction with real components. The invention is intended to allow components made of inhomogeneous materials or materials and / or with an inhomogeneous material / material distribution with regard to their mechanical

Capture properties and more preferably integrate them into digitized manufacturing processes. The determination of specific individual mechanical properties is preferably intended to enable these materials to be used in a load-compatible manner. Another object of the invention is preferably to reduce the reject rate in the production of components from fiber composite materials. It is also a task to reduce the safety coefficients, and thus to tap the potential of organic materials for lightweight applications.

This object is achieved according to the invention in that the component is subjected to a mechanical load which deforms the component and the deformation of the component at a plurality of defined measuring points or

Measuring sections is detected camera-based and the local deformation of the component is determined from the camera data and the local mechanical property is calculated from the local deformation.

A measuring point is not only a point in the mathematical sense, but also a location on the component with a finite extension.

A preferred development of the invention relates to a digital clone of inhomogeneous components / semi-finished products or workpieces that actually exist Materials or inhomogeneous material distribution. The digital clone represents the individual specific mechanical properties of the component as a model. It is the explicit representation of the result of an individual test of the mechanical properties of a real existing component, the

was recorded according to the invention in a digital manufacturing environment.

In this creation of the individual model, there is a significant difference to the now common principle of the digital twin. The digital twin as an established state of the art is an image of a non-real one

Component, i.e. only a component with the theoretical properties of the materials used. The digital twin is created during the

Construction process and exists even without its real twin. His

Properties reflect the material properties determined in analogy experiments, projected onto the respective component or semi-finished product geometry.

The digital clone as a preferred embodiment of the invention is the digital image of a real component or semi-finished product. As a specific result of an individual test according to the invention, it does not exist without an equivalent in reality. It follows that there is an individual CAD file for each component or semi-finished product that represents the digital clone.

The decisive innovation of this further training is the individual mapping of the inhomogeneities of the respective component or semi-finished product in an explicit digital model. The focus of the digital clone is on the digital or

computer-based representation of the individual local mechanical

Properties of the real existing model. He makes it possible

Make properties usable for constructions in a digital working environment, e.g. when planning products using CAD.

A component made of inhomogeneous material or inhomogeneous material distribution can preferably be positioned in the overall construction with the information from the digital clone in such a way that areas with particularly high mechanical

Properties are compared to the particularly stressed areas of the overall construction. At the same time, vulnerabilities in particular

Material is not a rejection criterion if they are only exposed to minor loads in the overall construction. The digital clone is preferably the representation of the results of a mechanical test in the form of an individual CAD file.

An essential part of the invention are the respective component or

Devices adapted to the semi-finished product for determining the mechanical

Properties, preferably the locally different mechanical properties, in particular a selected mechanical property from a large number of possible mechanical properties. A mechanical property is preferably understood to be one that characterizes the behavior of a component in relation to external stresses. Possible mechanical properties within the scope of the invention in terms of their local

Different occurrences in a component are examined, for example, the bending strength, the tensile strength, the compressive strength, the shear strength, the breaking strength, the modulus of elasticity, the shear modulus, the transverse contraction number.

Such a device comprises a device for loading the component to be tested, e.g. by exerting force on the component at selected points, so that the component is deformed compared to the unloaded case. The device further comprises at least one camera with which

different measuring points of the component, preferably at least at several different spaced measuring points along its extent, preferably the longitudinal extent, the component deformed under the load, optionally also the originally unloaded component, optically, e.g. is captured photographically or videographically.

If only one camera is used, it can be positioned differently to the component, e.g. along the extension, preferred

Lengthways different, e.g. equidistant, positioned to capture the component at the selected measuring point at each selected position,

in particular for what at least one recorded image or video for

subsequent evaluation is saved.

The invention can preferably also provide for a number of cameras to be used simultaneously for the acquisition, which corresponds at least to the number of (fixed) measurement points to be acquired or also measurement ranges of the component. When a preferably elongate component is detected, it can be provided that the plurality of cameras are arranged parallel to one another in a side-by-side arrangement

Longitudinal extension, preferably lined up equidistant.

The at least one camera preferably has an alignment of its optical axis perpendicular to the component longitudinal extent, preferably also an alignment of the optical axis also perpendicular to the force exerted. The type of load can preferably depend on the component and / or on the mechanical tested

Property in the facility can be selected differently, or different facilities are selected for this.

The mechanical load on the component to be tested takes place entirely in the area of the elastic deformation. Damage to the component or semi-finished product is excluded in this way. The form of the mechanical load is preferably based on the load to be expected when using or using the component or semi-finished product. The requirement for a purely elastic deformation leads to comparatively small test loads and

accordingly only slight deformations of the component to be tested.

Loads can be realized in different ways. Examples are the 3-point or 4-point load, an example of which is also described below. Other types of stress are e.g. Tensile, compressive, shear or torsional loads.

To determine the effects of the inhomogeneities of the tested component under the load, especially compared to the unloaded case

different processes can be used.

One possible method is that of image correlation. Although this method is known as the state of the art and enables a partial evaluation of the deformation under load on individual areas of the sample, the invention generally still provides regardless of the evaluation method used, e.g. by conversion, to determine an individual local value or several values of the respectively examined mechanical properties from the optically recorded local deformation of individual areas of a tested component, e.g. the

Flexural rigidity as a mechanical property. The exemplary application of image correlation in the invention is expressly not limited to evaluation in the visible light range. However, this is preferably carried out with visible light.

The local mechanical properties determined are preferred

Execution then mapped by the digital clone and made usable. Such a clone, depending on the number and direction of detection of the detected

Property values represent at least one vector or a matrix of the values.

The results of the component test are e.g. converted into a CAD file using selected algorithms. The algorithms preferably ensure that the digital clone accurately reproduces the properties of the tested component or semi-finished product in the required resolution.

For example, a recursive optimization of these algorithms can be carried out, e.g. through a particularly weak artificial intelligence.

In general, the invention can provide that the local deformation is determined in relation to the non-deformed component, in particular which is also recorded camera-based or is determined in relation to a deformed component assumed to be homogeneous, the deformation of which is simulated.

It can be provided here that, using a mathematical model that describes the deformation behavior of the component, in particular describes the deformation behavior of the component assumed to be homogeneous, from the measured values that represent the local deformation in relation to the non-deformed component, in particular in connection with the known forces used during loading by changing the model, a simulated deformed component described by the modified model is approximated to the real deformed component, in particular iteratively until a convergence criterion is met.

In a specific embodiment, the invention can provide the real deformation behavior of the tested component from inhomogeneous components

To depict or simulate materials / materials with the known methods of mechanics, eg with methods of finite elements (FEM). This can lead to multidimensional systems of equations that can be solved with iterative methods. The finite element method is generally established in the prior art and is therefore assumed to be generally known to the person skilled in the art.

In essence, it is a numerical procedure that

simulate the physical behavior of a body by calculating how the elements of the discretized body relate to the forces, loads and

Boundary conditions react and how loads and reactions propagate during the transition from one element of the body to the neighboring. It can thus be calculated numerically how a component discretized into finite elements deforms under a load.

A general form of the finite element method is e.g. given by:

{F} = [K] {U}

Here are all the forces acting on a component, in particular those that act on the nodes of the elements of the component into which the component is discretized. [K] is the total stiffness matrix, which includes all information about the geometric shape, the volumetric properties and solution methods from the exact mechanics for the component under consideration. The overall stiffness matrix comprises the coefficients and values formed therefrom for the individual element stiffness matrices of those elements in which the component is discretized. {U} is the solution in the form of displacements of the nodes of the discretized elements of the component. The areas that connect the discretized elements are understood as nodes.

The invention can generally apply methods of mechanics, e.g. the FEM, for example so that it is quasi inverted. This is to be understood in particular in such a way that a mathematical model, in the example one of the finite element method, is changed so that it describes the deformation behavior actually recorded. At least part of this model can form the digital clone mentioned.

In an exemplary embodiment, starting from a homogeneous component, which is based on an overall stiffness matrix of the finite element method is described, this overall stiffness matrix can be changed successively, in particular iteratively, in particular in one or more parameters

(Matrix coefficients) that, given the known load in the concrete test, a shape of the simulated component is created in the FEM simulation, which corresponds to the optically recorded shape of the component actually loaded within specified limits. For this, e.g. the parameters of the at least one overall stiffness matrix used in the FEM method of the component originally assumed to be homogeneous are changed iteratively until convergence with the optically recorded real component.

In one possible embodiment, the unloaded component and the loaded component can be optically recorded with the at least one camera. From a comparison of the recorded data (images / videos), e.g. As part of a computer-based image evaluation, the exact displacement of the component can be determined, or the displacement of the nodes of the elements into which the component is discretized in this method, thus the exact solution {UEX} in the FEM. In the image evaluation e.g. a position difference is formed between the deformed and undeformed component, in particular for the previously defined nodes of the elements in which the component is discretized. The position differences form, for example

Displacement of the nodes used in an FEM.

Furthermore, the load {F} is known, since this is specifically due to the one used

Load method or device and the acting forces is given. It can thus be numerical, e.g. a solution of the overall stiffness matrix is determined iteratively, with knowledge of the displacements {U EX} and the load {F}, in particular where at least some of the coefficients of this matrix represent the values of the local mechanical property sought.

The mechanical properties of the component generally result from the at least one, preferably iteratively changed, overall stiffness matrix, in particular with a local resolution that corresponds to the resolution when the component is discretized into finite elements, but at least in the resolution of the number of cameras or measuring points. According to the invention, the at least one overall stiffness matrix can directly change the digital one after the preferably iterative change Represent clone, or from this values are taken to form the digital clone.

An iteration can e.g. in such a way that the first digital clone generated, that is to say preferably the overall stiffness matrix of an FEM model of the component assumed to be homogeneous, is exposed to the loads on the real component test in a simulation using FEM methods. This initial simulation will, in particular due to the iterative solution chosen in its first solution {Ui}, initially deviate from the real component behavior, ie the real displacement of the element nodes. These deviations are preferably quantified, especially afterwards used to form a changed overall stiffness matrix.

In particular, the evaluation takes place e.g. analogous to the determination of the deformation behavior. For each deformation value generated in the component test, there is a correspondence as the evaluation point of the simulation. The quantified deviations are preferably an additional input variable for the generation of a second digital clone, preferably one compared to the first

Overall stiffness matrix changed matrix. This process is repeated several times until the deviations between the simulated and the real one

Component behavior lies within previously defined limits, in particular the iteration converges within the specified limits, i.e. a solution {U N} has been found whose deviation from the exact optically recorded solution {U EX} is less than or equal to the limit or the limits.

The total stiffness matrix determined after the iteration describes the selected one to be tested in at least one of the coefficients, preferably in several

mechanical property, e.g. mechanical rigidity, preferred

Flexural strength.

The overall stiffness matrix can be e.g. be changed (preferably iteratively) by changing the coefficients of the element stiffness matrices of the individual elements into which the component is discretized.

The overall stiffness matrix must be created individually for each component to be tested, in particular it depends on the material of the component and its shape. In the case of a bamboo cane as an exemplary component, it can be provided, for example, to iteratively change the element stiffness matrix assigned to each measuring point on the tube or the tube section that is recorded with the at least one camera, as a result of which the overall stiffness matrix of the component is also changed as a whole. For example, the tube outside diameter of the bamboo tube at each measuring point or section and the inside diameter can be included in the respective element stiffness matrix or the total stiffness matrix at each measuring location / section.

The outer diameter can e.g. Within the scope of the invention, measurement technology is used to determine it from the camera images or beforehand separately at each measurement point / section and then, as a fixed parameter, to be taken into account in an iteration.

By iteratively changing the inside diameter at each measuring point (at the camera position) or in each measuring section (e.g. between two cameras) as a variable variable to change the local property, e.g. the bending stiffness in the respective element stiffness matrix, the simulated component, e.g. The shape of the bamboo cane can be adapted to the optically recorded simulative.

After the convergence, the inner diameter values of the measuring points / sections form at least representatives of the chosen local sought

mechanical property, e.g. the bending stiffness or can be converted specifically into this by known mathematical relationships.

With an increasing number of tests carried out, the quality of the algorithms for generating the first digital clone can be continuously optimized. The coherence between real component behavior and the deformation behavior represented by the digital clone is continuously improved. The

The process described is repeated for each new component and each new test setup.

In another method, it can also be provided, in the case of a load, to determine a property value that is valid globally for the entire component, for example the bending stiffness, from a measured deformation value, first assuming a homogeneous component formation. With an exemplary 4-point load, the central maximum deflection of the component, for example, again, can be used for this Bamboo tube between the supports and the stamps compared to the unloaded case can be determined and from this, for example, the global bending stiffness of the component can be determined assuming a homogeneous composition. From this, the theoretical deformation of the component assumed to be homogeneous is calculated under the selected load type, for example the theoretical bending line of the component with a 4-point load.

On the basis of the captured images of the at least one camera, one

Difference formation between the positions of the loaded and unloaded component at the respective measuring point / measuring section and / or the gradients on one

Measurement point or between adjacent measurement points (= measurement section) of the loaded and unloaded component. The multiple difference values

(at least one per measuring point / section) can directly represent a representative measure of a mechanical property or can be converted into such a property on the basis of mathematical relationships that apply to the component and / or the type of load.

The invention can provide generally and therefore regardless of the type of evaluation that follows in general in the case of elongated components, the selected one

Property at several measuring points / measuring sections along the

To determine longitudinal extension. In principle, for example, tubular components, rod-shaped components and flat components can be examined.

In a further development, after such a measurement, the component is rotated by an angular amount about its longitudinal axis and the measurement is repeated, possibly several times for several different angles, so that several measurements for determining the selected property at several different angles

Longitudinal positions and several different circumferential positions are available.

In fact, the component surface can be completely captured, i.e. it can be captured from several directions, even though the cameras relate to the

Earth reference system capture the component in only one direction.

In particular in connection with the finite element method described above, the required displacements of the nodes of the discrete elements of the component in space can be determined more precisely. A possible embodiment of the described invention is quality assurance for an elongated or elongated, for example tubular component, for example a naturally grown bamboo tube. This component, for example bamboo cane, generally has large inhomogeneities distributed over its length and over the circumference. In the context of the invention, a bamboo tube is a preferred component, since its structure, as a naturally grown bamboo tube, is a bionic model for modern lightweight constructions. Bamboo cane has a stiffness to ratio

Weight on the level of alloy aluminum tubes. Bamboo can be used for a variety of products, e.g. among other things as material for the construction of bicycle frames. Use in scaffolding or other stiffening structures is also known.

The greatest loads occurring with elongated components, e.g.

Bamboo tubes are bending moments that act on the component.

In this exemplary application, the invention accordingly has the task of investigating the inhomogeneous distribution of the bending stiffness of the component, e.g. of the bamboo cane to record and map.

Both the absolute local size of the bending stiffness, or at least representative values, as well as their position on the circumference and the length of the component, e.g. of a naturally grown bamboo cane. In a further preference, the mechanical property determined, e.g. the bending stiffness selected here is represented in the form of the digital clone.

An emerging digital model of each made from multiple components

Product, e.g. A bicycle frame is one of several inhomogeneous ones

Components, e.g. Bamboo cane composite structure. The digital model thus consists of the individual digital clones of the components used. With the information about the local bending stiffness distribution of the components used, e.g. Bamboo tubes, the composite structure is also mapped by a digital clone.

To determine the local bending stiffness, the component, e.g. a bamboo cane loaded. The mechanical load is e.g. a 4-point bending test was chosen.

In this case, the component is preferably placed on two spaced-apart supports and loaded with two spaced-apart punches arranged between them. The 4-point bending test has the advantage of introducing a shear-free bending load on the component under investigation, for example the bamboo tube, between the loading punches. The longitudinal axis of the component is marked by the x coordinate. This is shown, for example, in Figures 1 to 4. The distances between the load application and support are, for example, different from the standard for 4-point bending tests

adjusted according to the available component geometry and the desired evaluation length.

In the example of a bamboo tube, the area free of lateral force in the sample is e.g. with a length of 1 m selected so that all for later use in one product, e.g. relevant component lengths are mapped to a bicycle frame. The applied load is preferably dependent on the pipe diameter examined and is limited by the specification of the purely elastic deformation. For the

Evaluation according to the invention, a plurality of cameras are mounted parallel to the longitudinal extent, with which the component is recorded in sections over its longitudinal extent, in this example parallel to the longitudinal axis of the

Bamboo cane with ten cameras, such as shown in picture 4.

The simultaneous evaluation of several camera images enables the complete evaluation length to be recorded.

For the image correlation used as an example, in each case the exposure of an individual camera in the unloaded state is compared to the corresponding exposure after the test load has been applied. For a component, e.g. a tube made of a homogeneous material would result in a constant bending line for the load case, Figure 2.

In this case, the measured deflection is a function of the x coordinate along the longitudinal extent or longitudinal axis of the component, for example the bamboo tube. For the inhomogeneous material in the component, eg bamboo cane, there is a bending line whose local deflection and slope is directly dependent on the local distribution of the bending stiffness in the respective component being examined. Picture 3). In direct comparison to the deformation of a component with a homogeneous material distribution, areas in the component, for example bamboo cane with high bending stiffness, lead to a locally flat slope of the bending line. Areas with weaknesses or defects, which lead to a local reduction in the bending stiffness are shown in the form of a larger slope.

In a naturally grown bamboo cane as an exemplary component, both forms of deviation can also be found in direct succession.

Figure 3) shows the resulting bending line. To the distribution and size of the

Inhomogeneity across the circumference of the component, e.g. To map the bamboo tube, the component is rotated several times around its longitudinal direction at a defined angle. In the new position, the corresponding images are again created and compared in an exemplary evaluation in the loaded and unloaded state. The determined values of the local deformation can already be understood as representatives of the local bending stiffness and can preferably be converted into local stiffness.

As previously described, the determined values can also be used to form the exact measured solution {UEX} within the framework of an FEM. The iterative calculation of the overall stiffness matrix thus effectively converts the determined values into the local bending stiffness values sought.

In a preferred development, the result of the examination is represented by the digital clone, in particular namely by the determined overall stiffness matrix of the component, and this local stiffness determined in the form of a CAD file.

The invention makes no statement about the cause of the local

Bending stiffness distribution made. This statement is of secondary importance for quality assurance. What is crucial is a reliable statement about the actual mechanical properties of the component used or the bamboo tube and the location and classification of any weak points that may be present. In the example, such weak points can be identified by a locally large deformation.

The advantage of the invention is the direct determination of the locally different ones relevant for the use of the respective component or semi-finished product

mechanical properties. Another possible exemplary embodiment of the described invention is quality assurance for shell-shaped structural components or cladding parts made of preferably fiber composite materials. These components are often characterized by a very low material thickness or thickness in relation to the other dimensions of the component.

State of the art is the evaluation of the manufacturing process or

Conversion of the material distribution and internal structure of a component or

Sheet material in a statistical value for the mechanical properties. As a potential source of error, this detour leads to high safety factors regardless of the resolution of the measurement or evaluation methods used.

The digital clone contains information about the size and distribution of the mechanical properties in a component that have been examined as relevant

inhomogeneous material and makes it usable.

State of the art is the determination of the minimum mechanical properties and the dimensioning of the entire component based on this size. In

For areas with locally better mechanical properties, however, this procedure leads to oversizing, which can be avoided in the invention.

In the quality assurance of components made of fiber composite materials, every documented deviation in the manufacturing process leads to a potential defect and regardless of the actual impact of this defect on the

mechanical properties of the component to scrap. The invention enables the relevant mechanical properties to be determined directly. Defects without any impact on the mechanical properties can be identified with the invention and accordingly reduce the reject rate.

Comparable components can according to the invention locally by a pin or

The probe body is loaded with a bump in the surface. This bulge generated by the load can be determined geometrically using an image correlation application according to the invention. The shape of the bulge is proportional to the mechanical properties of the exposed area and its surroundings. The invention and the method described are also suitable for quality assurance of complex components. Here too, a condition for use is preferably a damage-free deformation of the component in the elastic region. It makes sense to use all components or semi-finished products for one

mechanical load can be designed in the application.

The implementation of the measuring method is shown in Figures 1 to 4 with reference to a rod-shaped, preferably tubular component, e.g. to take a bamboo cane. FIG. 5 shows a flow chart from which an exemplary embodiment for various exemplary component shapes a), b), c) can be found. The

Performing photogrammetry is optional.

Claims

claims

1. Method for the non-destructive determination of local mechanical

Properties of a component, preferably an elongated component made of inhomogeneous materials or an inhomogeneous material distribution, the component being exposed to a mechanical load which deforms the component and the deformation of the component is detected on a plurality of defined measuring points or measuring sections and the local deformation of the component is determined from the camera data and the local mechanical property is calculated from the local deformation.

2. The method according to claim 1, characterized in that the introduction of the load is carried out in the context of a bending test, in particular a 4-point bending test, a tensile test, a compression test or another method for material testing.

3. The method according to any one of the preceding claims, characterized in that the non-destructive deformation takes place in the elastic region of the component.

4. The method according to any one of the preceding claims, characterized in that, in particular depending on the type of introduction of the force into the component, by evaluating the detected deformation as mechanical

Property the strength, especially the flexural strength, the

Compressive strength, the tensile strength, kink, shear and / or torsional strength and / or the stiffness, in particular the bending, elongation, shear and / or torsional stiffness is determined.

5. The method according to any one of the preceding claims, characterized in that a digital model, in particular for generating a digital clone, from the determined local mechanical properties of the component is formed, in particular with which the actually existing component is represented in a digital construction environment of a computer.

6. The method according to any one of the preceding claims, characterized in that the deformation of the component is detected as a local deformation at the plurality of measuring points / measuring sections with at least one camera, which is successively moved to different positions along the extent of the component to detect the component at a respective measuring point / measuring section or simultaneously with a large number of cameras positioned differently along the extent of the component.

7. The method according to any one of the preceding claims, characterized in that the local deformation is determined in relation to the non-deformed component, in particular which is also recorded camera-based or is determined in relation to a deformed component assumed to be homogeneous, the deformation of which is simulated.

8. The method according to claim 7, characterized in that by means of a mathematical model which describes the deformation behavior of the component, in particular describes the deformation behavior of the component assumed to be homogeneous, preferably with the model of the finite elements, from the recorded measured values, which the local deformation represent in relation to the non-deformed component, especially in connection with the known forces used during loading by changing the model, the simulated deformed component described by the modified model is approximated to the real deformed component, in particular iteratively until a convergence criterion is met.

9. The method according to claim 8, characterized in that to change the model, the overall stiffness matrix in the model of the finite elements is changed.

10. The method according to any one of the preceding claims 8 or 9, characterized

characterized in that the digital clone is determined from the modified model, in particular the overall stiffness matrix determined during the change, and in particular the determined overall stiffness matrix represents it.

11.Device for carrying out the non-destructive determination of local mechanical properties of components, preferably elongated components made of inhomogeneous materials or with inhomogeneous material distribution, comprising a device for loading the component and at least one camera, preferably a plurality of cameras, with which the respective local deformation is recorded at a respective measuring point / measuring section.

12. The apparatus according to claim 1 1, characterized in that with the

The entire surface of the component can be detected by cameras, in particular the cameras enable detection of the component and its deformation from several directions, preferably by successive detection after several component rotations about a component axis, preferably about the longitudinal axis.

13. Components made of inhomogeneous materials by means of computer-based

Construction are produced using the data determined by the method according to one of the preceding claims 1 to 10.