Digital Photoelastic Evaluation of Isochromatic Fringe Order in a 3D Model of Complex Rocket Motor Strap- on Joint

Ashokan, K.; Ramesh, K.; Pillai, S. Annamala; Philip, Jeby

doi:10.1007/978-1-4020-6239-1_41

Cited by 2 publications

(2 citation statements)

References 2 publications

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“…More details regarding this model can be obtained from Ref. [29]. Dark‐field isochromatics of the entire slice obtained using the white light source is shown in Figure 8A.…”

Section: Application Of the Methodology To Complex Modelsmentioning

confidence: 99%

Adaptive Quality Guided Phase Unwrapping Algorithm for Whole‐Field Digital Photoelastic Parameter Estimation of Complex Models

Ramji

Ramesh

2010

Strain

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With advancements in digital image processing and data acquisition, a separate branch of photoelasticity namely digital photoelasticity came into existence. Here, intensity information of the acquired image is used for the evaluation of whole‐field photoelastic parameters. Digital photoelasticity provides only wrapped phasemaps of isoclinics and isochromatics and they have to be unwrapped in different ways for getting the continuous‐phase values. In the case of the isochromatic phasemap, ambiguity removal prior to unwrapping is essential. In this paper, a 10‐step phase‐shifting methodology is proposed and a new strategy for obtaining the isochromatic phasemap free of ambiguity is demonstrated. Isoclinic unwrapping is performed by a new adaptive quality guided algorithm. Adaptive in the sense that isoclinic phase unwrapping is done autonomously even in the presence of isotropic points/π jumps occurring in the isoclinic phasemap. The isochromatic phasemap is also unwrapped using the quality guided path follower. The methodology is validated for the problem of a ring under diametral compression and later shown for three other models which have complex stress fields. Wherever possible, the parameters obtained by the new methodology are compared with analytical or numerical methods and the comparison is quite good.

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“…More details regarding this model can be obtained from Ref. [29]. Dark‐field isochromatics of the entire slice obtained using the white light source is shown in Figure 8A.…”

Section: Application Of the Methodology To Complex Modelsmentioning

confidence: 99%

Adaptive Quality Guided Phase Unwrapping Algorithm for Whole‐Field Digital Photoelastic Parameter Estimation of Complex Models

Ramji

Ramesh

2010

Strain

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“…Three-dimensional model of the joint comprising a ball insert, base ring bush and base ring block is fabricated using epoxy resin (Araldite CY-230) and hardener (HY-951) supplied by Huntsmann Advanced Materials India Private Ltd. to a model to prototype scale of 1:2. 36 The fabricated parts are then assembled, loaded and stress frozen. A force of 40 N is applied using dead weight along the ball centre.…”

Section: Application To a Practical Problemmentioning

confidence: 99%

New initiatives in single-colour image-based fringe order estimation in digital photoelasticity

Ramesh

Ramakrishnan

Ramya

2015

The Journal of Strain Analysis for Engineering Design

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The use of single-colour image for determining the fringe orders in digital photoelasticity has gained importance in recent years, and in this, the fringe orders are obtained by comparing the colour information at each pixel of the model image using a calibration table. They were originally used for identifying fringe orders of up to 3, and there have been attempts to extend this to higher fringe orders. The methods proposed were tested only for the special case of the application specimen where the fringe signature is similar to that in the calibration specimen for fringe orders beyond 3. In this article, various colour difference formulae are studied, and a new colour difference formula is proposed to handle fringes beyond 3. The advantage of the new colour difference formula is illustrated for the problem of a thick ring subjected to internal pressure and a finite plate with a hole. A new multi-directional smoothing methodology is proposed to smooth the fringe order obtained. The results are compared with those obtained by 10-step phase shifting technique. Advancing front scanning approach coupled with multiple seed points is used to solve a variety of problems in which both the geometry and the fringe signature are quite different from the calibration specimen. The influence of seed point selection is brought out by solving the problem of a plate with a hole having up to 15 fringe orders. New approaches to handle noisy industrial images are also dealt with.

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Digital Photoelastic Evaluation of Isochromatic Fringe Order in a 3D Model of Complex Rocket Motor Strap- on Joint

Cited by 2 publications

References 2 publications

Adaptive Quality Guided Phase Unwrapping Algorithm for Whole‐Field Digital Photoelastic Parameter Estimation of Complex Models

Adaptive Quality Guided Phase Unwrapping Algorithm for Whole‐Field Digital Photoelastic Parameter Estimation of Complex Models

New initiatives in single-colour image-based fringe order estimation in digital photoelasticity

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