Siebert T.,Dantec Dynamics GmbH |
Splitthof K.,Dantec Dynamics GmbH |
Lomnitz M.,Dantec Dynamics GmbH
Conference Proceedings of the Society for Experimental Mechanics Series | Year: 2017
In material testing optical techniques take more and more over the role of classical mechanical length changing tools. Beside simple 1-dimensional measurement methods, full field techniques like digital image correlation (DIC), allow 2- or 3-dimensional characterisation of the materials and components. Especially for anisotropic materials the multidimensional information is important. E.g. up to now this is limited to 2D strain information on plane surfaces. Nowadays, the application of the DIC technique moves from academic to industrial fields. In this interest, one needs to prove the DIC technique on real components. The conventional 2-cameras 3D DIC inspection becomes then non-optimal since complex geometries imply hidden areas. The approach of using more than minimum required number of camera views overcome these limitations. An efficient way to overcome these limitations is to take advantage of the use of multi-cameras DIC system. This idea is already commonly used in other fields like photogrammetry. This publication describes the idea and principle of using the Cluster Approach for multi-cameras DIC systems. In order to illustrate the implications of this new technique, we present strain measurements in tensile testing and deformation measurements on complex geometrical structures. © The Society for Experimental Mechanics, Inc. 2017.
Wang W.,University of Liverpool |
Mottershead J.E.,University of Liverpool |
Siebert T.,Dantec Dynamics GmbH |
Pipino A.,Centro Ricerche Fiat
Mechanical Systems and Signal Processing | Year: 2012
The availability of high speed digital cameras has enabled three-dimensional (3D) vibration measurement by stereography and digital image correlation (DIC). The 3D DIC technique provides non-contact full-field measurements on complex surfaces whereas conventional modal testing methods employ point-wise frequency response functions. It is proposed to identify the modal properties by utilising the domain-wise responses captured by a DIC system. This idea will be illustrated by a case study in the form a car bonnet of 3D irregular shape typical of many engineering structures. The full-field measured data are highly redundant, but the application of image processing using functional transformation enables the extraction of a small number of shape features without any significant loss of information from the raw DIC data. The complex bonnet surface on which the displacement responses are measured is essentially a 2-manifold. It is possible to apply surface parameterisation to 'flatten' the 3D surface to form a 2D planar domain. Well-developed image processing techniques are defined on planar domains and used to extract features from the displacement patterns on the surface of a specimen. An adaptive geometric moment descriptor (AGMD), defined on surface parametric space, is able to extract shape features from a series of full-field transient responses under random excitation. Results show the effectiveness of the AGMD and the obtained shape features are demonstrated to be succinct and efficient. Approximately 14 thousand data points of raw DIC measurement are represented by 20 shape feature terms at each time step. Shape-descriptor frequency response functions (SD-FRFs) of the response field and the loading field are derived in the shape feature space. It is seen that the SD-FRF has a similar format to the conventional receptance FRF. The usual modal identification procedure is applied to determine the natural frequencies, damping factors and eigen-shape-feature vectors from the SD-FRF. Natural frequencies and mode shapes from a finite element (FE) model are correlated with the experimental data using the cosine distance between the shape feature vectors with 20 terms. There are numerous benefits of using image decomposition to analyse 3D DIC measured data, including (1) representation of the raw measurement data with efficiency and succinctness; (2) determination of the FRF of any point on the specimen by the use of the full-field shape features; and (3) elimination of DIC measurement noise. Also, the SD-FRF is potentially ideal for cases of field excitation of structures. © 2011 Elsevier Ltd. All rights reserved.
Agency: European Commission | Branch: FP7 | Program: BSG-SME | Phase: SME-2011-1 | Award Amount: 1.29M | Year: 2011
The CreepImage project will develop a digital image technique for long term measurement and monitoring of creep deformation of an engineering structure/component under harsh conditions (high temperature, irradiation etc) where direct sensor attachment and human access are difficult or dangerous. A high definition digital camera equipped with a suitable lens (macro, telescopic or telecentric lens) will be used to capture images of a grid on the component surface at various stages, and digital image correlation (DIC) will be used to calculate the deformation associated with creep behaviour of the component. The procedure is expected to be as follows: (1) Physically produce a grid on the surface of the structure. It serves as the information carrier from which deformation can be calculated by DIC. (2) Capture digital images of the grid at different stages. A reference plate with a stable known coefficient of thermal expansion (CTE) will be placed adjacent to the grid such that it can be imaged simultaneously. This permits automatic calibration without the need to keep the camera on site all the time. (3) DIC software will be used to calculate the overall deformation. Creep strain is obtained by subtracting the thermal deformation. The project work will be a laboratory based demonstration to validate the proposed techniques and to investigate the measurement capability (accuracy, repeatability etc). In addition to nuclear plants, other potential application areas include evaporators in a power plant.
Agency: European Commission | Branch: FP7 | Program: CP-IP | Phase: GC.NMP.2012-2 | Award Amount: 13.42M | Year: 2012
Hybrid-EVs and Full-EVs on the market are products where the Internal-Combustion-Engine (ICE) is supplemented by an electric-motor (HEV) or replaced by an all-electric power-train (FEV). Both approaches do not address lightweight or modularity inheriting the same disadvantages as conventional ICEV - Electrification of mobility must face a conceptual rEVOLUTION! This project breaks the paradigm of current Body-in-White (BiW) by delegating the whole structural function to a novel BiW archetype made up of a Multifunctional-Rolling-Chassis (MRC) enabled by a new generation of highly-hybridized structural components and complemented by a non-structural upper-body. This MRC will be the common basis for a family of user friendly vehicles differing by changing only the upper-body according to the customer demand. Advanced materials will enable the development of novel super-lightweight hybrid components complying with safety standards and recycling constraints, and enable the design of the innovative MRC for FEV leading to a further weight reduction of 40% over that achieved using the current state of the art in the SuperLIGHT-CAR project. The EVolution goal is to demonstrate the sustainable production of a 600 kg weight FEV by the end of 2015. To this end EVolution addresses the whole vehicle by prototyping, assembling, and disassembling, the most representative components (MRC, crash cross-beam, crash box, suspension sub-frame, side-door, A-pillar, and a multifunctional-hard-top) made from raw polymers and aluminum alloys commonly used in the automotive industry, to ensure compliance with EC Directive 2000/53/EC End-of life vehicle which imposes stringent requirements on the disposal and recycling of motor vehicles. Guaranteeing the safety and regulatory compliance, with a weight saving of 50%, each component chosen will prove, mutatis mutandis, the revolutionary potential of the EV solution in all components employed today in current high volume production.
Agency: European Commission | Branch: FP7 | Program: CSA-SA | Phase: NMP.2012.4.0-2 | Award Amount: 587.89K | Year: 2013
Engineering simulation is an essential feature of the design and manufacture of all engineered products at all scales. However such simulations are not routinely validated, at least in part because technology for rapid, cost-effect validations has not been available. Two previous projects, SPOTS and ADVISE have led to the development of appropriate technology. The goal of the VANESSA project is to establish the validation methodology and the associated calibration procedures within a standards framework and to promote the adoption of the methodology within the European industrial and scientific communities. It will deliver a CEN Workshop Agreement on the validation of computational solid mechanics models using strain fields from calibrated optical measurement systems. It is expected that this innovative approach to design validation will be taken up by EU industrial base leading to a strengthening of the position of European industry. The technical approach embedded in the validation process has the potential to stimulate improved quality control for the process chain from design, during production and certification, through to service and maintenance.
Agency: European Commission | Branch: FP7 | Program: JTI-CS | Phase: JTI-CS-2011-3-SFWA-02-019 | Award Amount: 799.12K | Year: 2013
The BirdStrike project aims to establish a validated bird strike analysis capability, which enables the SFWA partners to simulate bird impact on a CFRP leading edge for a NLF wing. This will be achieved by setting up a combined program of test and analysis to determine the extent of damage and criteria to be applied to analyses of leading edge panels for NLF wings. The main scientific and technical work comprises six main research objectives in agreement to the present Call for Proposals (CfP) topic: 1) Analysis of bird strikes on flat and representative curved panels at various angles of impact, using an existing bird impact model that will be provided by the SFWA Partners. 2) Design and analysis of a supporting frame for bird-strike impact tests on flat and representative curved panels. 3) Manufacturing of an agreed number of flat and representative curved panels that include supporting stringers, sparcaps or other structural features. 4) Completion of impact tests at various angles. 5) Validation of analyses and numerical models. 6) Delivery of a tool that can predict the extent of damage in a representative Composite LE geometry.
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: SST-2007-4.1-01 | Award Amount: 2.79M | Year: 2008
ADVISE is a prenormative project for experimental validation of simulations of dynamic events using full-field optical methods of deformation measurement. These powerful tools are used in evaluating the performance, reliability, and safety of primary structures and for validating their computational design. Optimised design of primary structures leads to lighter and more energy efficient products that cost less, are more reliable and safer. Whilst in engineering modelling the analysis of homogeneous materials subject to impact has become fairly routine, recent advances have been made in modelling the impact of two-dimensional composites. ADVISE brings together advances in optical techniques with the developments in modelling composites in order to establish high levels of confidence through rigorous validation. Such an approach would represent a step change in the subject. The innovative aspects and objectives of the project are: development of reference materials that allow traceability and calibration of full-field optical methods of deformation measurement in cyclic, transient and non-linear dynamic events; optimisation of methodologies for both optical measurement and computational modelling and simulation of non-linear, transient dynamic events; contributions to standardisation activity for experimental validation of dynamic simulations. This represents the first attempt to provide a unified approach to experimental validation of engineering simulations of primary structures subject to dynamic processes, the development of reference materials for optical dynamic deformation measurement. The major contribution to standardisation through VAMAS TWA 26 ensures that the reference materials can become quickly accepted globally, thus providing worldwide traceability for validated designs leading to safer transport systems. Direct dissemination to the EU industrial base will be a priority to maximise the benefits of this research.
Wang W.,University of Liverpool |
Mottershead J.E.,University of Liverpool |
Ihle A.,High Performance Space Structure Systems GmbH |
Siebert T.,Dantec Dynamics GmbH |
Reinhard Schubach H.,Dantec Dynamics GmbH
Journal of Sound and Vibration | Year: 2011
The comparison of structural responses, e.g. natural frequencies and mode shapes, between predictions and measurements is an important step in finite element (FE) model updating. Full-field measurement techniques such as high speed cameras with digital image correlation (DIC) algorithms provide detailed, global displacement data. It is necessary to compress huge amounts of full-field data before implementing the comparison procedures. Image processing and pattern recognition techniques offer effective ways of doing this. Image decomposition using integral transformation is one of the most common procedures. It is found that appropriate selection or construction of the transformation kernels usually generates succinct and effective shape feature terms. Thus, the discrepancies between the geometric mode shapes may be assessed by using distance measures between the shape feature vectors. In the present study, vibration mode shapes of a composite panel are measured by a DIC system and predicted by a FE model. Succinct and effective shape features of the full-field mode shapes were obtained by employing the Tchebichef moment descriptor. Mode shape discrepancies are clearly indicated by the resultant Tchebichef features. The FE model was then modified and updated. Results show that including only the shape features results in a better updated model than when natural frequencies only are used. The most improved model was obtained when both natural frequencies and shape features are included in the updating routine. © 2010 Elsevier Ltd. All rights reserved.
Brucker C.,TU Bergakademie Freiberg |
Hess D.,TU Bergakademie Freiberg |
Kitzhofer J.,DantecDynamics GmbH
Measurement Science and Technology | Year: 2013
Scanning PIV as introduced by Brücker (1995 Exp. Fluids 19 255-63, 1996a Appl. Sci. Res. 56 157-79) has been successfully applied in the last 20 years to different flow problems where the frame rate was sufficient to ensure a 'frozen' field condition. The limited number of parallel planes however leads typically to an under-sampling in the scan direction in depth; therefore, the spatial resolution in depth is typically considerably lower than the spatial resolution in the plane of the laser sheet (depth resolution = scan shift Δz ≫ pixel unit in object space). In addition, a partial volume averaging effect due to the thickness of the light sheet must be taken into account. Herein, the method is further developed using a high-resolution scanning in combination with a Gaussian regression technique to achieve an isotropic representation of the tracer particles in a voxel-based volume reconstruction with cuboidal voxels. This eliminates the partial volume averaging effect due to light sheet thickness and leads to comparable spatial resolution of the particle field reconstructions in x-, y- and z-axes. In addition, advantage of voxel-based processing with estimations of translation, rotation and shear/strain is taken by using a 3D least-squares matching method, well suited for reconstruction of grey-level pattern fields. The method is discussed in this paper and used to investigate the ring vortex instability at Re = 2500 within a measurement volume of roughly 75 × 75 × 50 mm3 with a spatial resolution of 100 m/voxel (750 × 750 × 500 voxel elements). The volume has been scanned with a number of 100 light sheets and scan rates of 10 kHz. The results show the growth of the Tsai-Widnall azimuthal instabilities accompanied with a precession of the axis of the vortex ring. Prior to breakdown, secondary instabilities evolve along the core with streamwise oriented striations. The front stagnation point's streamwise distance to the core starts to decrease while the rear stagnation point distance remains constant which indicates that the front part of the ring is at first losing its mass during breakdown. © 2013 IOP Publishing Ltd.
Walz T.,Dantec Dynamics GmbH
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011
For many years, optical measurement methods have been moving from research institution laboratories to industrial applications. Compact laser-based systems using the principles of speckle interferometry and easily manageable image correlation systems permit the simple and reliable high-precision characterization of materials and components in many different static and dynamic applications. The full-field, non-contact measurement of contours, deformations and strains has distinct advantages over conventional measurement methods resulting in significantly shorter development and testing times. The option of using full-field characterization also for transient events with a high time resolution opens prospects for many new applications in the future. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).