Improving DIC Accuracy in Experimental Setups

Reis, Martin; Adorna, Marcel; Jiroušek, Ondřej; Jung, Anne

doi:10.1002/adem.201900092

Cited by 17 publications

(14 citation statements)

References 17 publications

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“…Only one of these focusses on struts of open-cell metal foam. So far, however, Reis et al [ 15 ] have only provided the basis for the evaluation of microbending tests on individual foam struts by developing a method for high-precision DIC measurements on metal foam struts. An actual determination of material parameters from bending tests did not take place so far.…”

Section: Discussionmentioning

confidence: 99%

“…It shows large positive strains on the opposite side of the mandrel and negative strains at the point of load application. In Reis et al [ 15 ] three-point bending tests on individual struts are used to prove the accuracy of the DIC setup, without presenting the experimental results of the strut tests in detail. Two-point bending tests on cell walls or on individual struts are not common in the literature.…”

Section: Introductionmentioning

confidence: 99%

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Micromechanical Characterisation of Ni/PU Hybrid Foams

et al. 2020

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The computer-aided design of individual parts and the desire for weight reduction and material savings require further development of new hybrid materials. Ni/PU hybrid foams as a new hybrid material offer great potential for the production of components that are lightweight and yet can absorb large amounts of energy. The development of this structured material is at its beginning and mechanical characterisation on all scales is necessary. Experimental investigations on individual struts must be carried out on the micro scale to understand the structure-properties-relationship. Inspite of the challenges raising due to the complex geometry of the struts, tensile tests, three-point bending tests and micro sections are presented in this work. Due to the stiff Ni coating on the outer diameter of the struts, the resistance against bending is around five times as high as against tensile loading. The correlation between the behaviour of the struts and the macroscopic material behaviour validates the planned use of the foams as energy absorbers.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Micromechanical Characterisation of Ni/PU Hybrid Foams

et al. 2020

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“…For this purpose, the captured pictures are divided into subsets. All subsets must have a different, random pattern, which is achieved by spraying a black and white pattern onto the specimen's surface . Initially, the specimen surface is inspected for roughness and, if necessary, sanded smooth.…”

Section: Methodsmentioning

confidence: 99%

Digital image correlation strain measurement of ultra‐high‐performance concrete‐prisms under static and cyclic bending‐tensile stress

Harenberg

Pahn

Malárics‐Pfaff

et al. 2019

Structural Concrete

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This paper provides experimental results on investigations for the validation of photogrammetric strain measurements of ultra-high-performance concrete (UHPC)-prisms subjected to static and cyclic bending-tensile stress. For this purpose, 4 static and 5 cyclic test series were performed. Damage progresses during loading are monitored by means of a digital image correlation (DIC) system and a clip gauge. The control of the DIC by trigger lists and the measurement noise as a function of the measurement rate are examined. All static tests were performed force controlled with the same testing speed and the same measuring rate of DIC and clip gauge. All cyclic tests were performed with the same upper and lower stress levels but with different loading rates. During the static tests, the DIC can be used to make accurate strain measurements before UHPC failure. In the cyclic tests, the measurement noise of the DIC decreases with an increasing measuring rate. The tests performed confirm the control of the DIC by trigger lists for cyclic tests on UHPC-prisms and show that the measurement noise is negligible in static and cyclic tests. K E Y W O R D S cyclic bending tests, DIC, fatigue, photogrammetry, UHPC

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“…Due to the small dimension of the setup in the presented work here, the target needs to be changed to threepoint bending specimen. A detailed explanation of target, setup and analysis can be found by Reis et al [4]. Calculating the force using Bernoullian beam theory and comparing it to the sensor measured force presents impressive results.…”

Section: Noise Measuring and Reduction Routinementioning

confidence: 99%

“…In this case, several image sets of 50 images in six different brightness levels with neither the camera nor the specimen moving were recorded. As subset size 19 × 19 px 2 is chosen, for further details see [4]. Fig.…”

Section: Noise Measuring and Reduction Routinementioning

confidence: 99%

Noise reduction for DIC measurements

Reis

Diebels

Jung

2019

Proc Appl Math and Mech

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Digital image correlation (DIC) is well known as a contact‐less, full‐field strain and displacement measuring method. The use of the method is widely spread in experimental mechanics. Nevertheless, there are error sources such as light settings, speckle pattern and noisy images, which strongly affect measurement quality, but often stays uninvestigated. Therefore, this work outlines a simple routine to identify errors and enhance the accuracy of DIC measurements. A calibration sample adapted to the specifications of the setup using the beam theory to link machine displacement, DIC measurements and forces. All evaluations are done in the commercial software ISTRA4D. The noise in the measurements is reduced to an error of under two per cent. The routine allows estimating the quality of the images before performing the experiments. Furthermore, the routine is transferable to all experimental setups. The calibration of the setup allows getting reliable experimental results with a known error. With this estimated stochastic error, the advantages of DIC can be used to evaluate mechanical experiments such as three‐point bending tests on single struts of an open cell metal foam.

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Improving DIC Accuracy in Experimental Setups

Cited by 17 publications

References 17 publications

Micromechanical Characterisation of Ni/PU Hybrid Foams

Micromechanical Characterisation of Ni/PU Hybrid Foams

Digital image correlation strain measurement of ultra‐high‐performance concrete‐prisms under static and cyclic bending‐tensile stress

Noise reduction for DIC measurements

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