Optical method of caustics applied in viscoelastic fracture analysis

Gao, Guiyun; Li, Zheng; Xu, Jianmin

doi:10.1016/j.optlaseng.2011.01.012

Cited by 20 publications

(3 citation statements)

References 12 publications

(14 reference statements)

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“…Namely, caustics have been used in dynamic problems, [6][7][8][9][10] in contact problems, [11][12][13][14] in stress intensity problems, [15][16][17] in obtaining stress-optical and elastic constants of materials, 18,19 and in the evaluation of J-integral. 20 Also, a variety of materials have been tested by the aid of caustics, such as anisotropic ones, 21 viscoelastic materials, 22 composite, 23 and even graded 24 materials. What is more, the method has been revisited several times, sometimes to reveal further useful properties of caustics, 25 and some other times to improve 26,27 or even to be extended to the more general case of curves entering the complex plane.…”

Section: Introductionmentioning

confidence: 99%

A simple formula for calculating the tensile strength of brittle materials by means of the circular semi‐ring test and the optical method of caustics

Markides

2020

Mat Design & Process Comms

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The tensile strength of brittle materials is here obtained by applying the experimental method of caustics to the circular semi-ring test (CSR). In this context, first the equations of the initial and the respective caustic curves are obtained for the CSR for light reflected from the front and rear face of the CSR as well as for transmitted light, thus covering all cases for both opaque and transparent materials. It is seen that the radii of the initial curves assume complex and real values with only the latter being accepted to form the loci on the CSR to provide the caustics. Then, simple closed-form formulae are provided for determining the critical stresses at the critical points A and B on the inner and outer perimeter of the CSR, in terms of the caustics' horizontal diameter D X .

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Section: Introductionmentioning

confidence: 99%

A simple formula for calculating the tensile strength of brittle materials by means of the circular semi‐ring test and the optical method of caustics

Markides

2020

Mat Design & Process Comms

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“…In this context, a wide variety of problems has been confronted by the method of caustics, as, the description of the stress intensity in T elastostatic problems [8][9][10], the mechanical behaviour and crack propagation under dynamic loading conditions [11][12][13][14][15][16][17], the measurement of strain concentration in plasticity problems [18], the determination of the J-integral [19], the determination of stress-optical as well as elastic constants of materials [20][21][22], the location of the crack-tip position [23], the description of load distribution and the definition of the contact length in contact problems [24][25][26][27][28][29]. What is more, the method has been successfully applied to a wide range of materials, including birefringent ones [30], rock-like [31] and anisotropic ones [32][33][34][35], viscoelastic ones [36] and even composite [37] or graded ones [38]. In parallel, several studies have concerned with the improvement of the method of caustics [39][40][41][42][43] while an experiment on the method of Caustics for educational purposes was recently proposed by Younis [44].…”

Section: Introductionmentioning

confidence: 99%

Double initial and caustic curves in diametrically compressed transparent discs - Application to the contact length

Markides

2019

Frattura Ed Integrità Strutturale

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General formulae for double initial and caustic curves (reflected and transmitted) are obtained in the case of smooth contact of two cylindrical elastic bodies of arbitrary radii. Namely, based on the method of reflected and transmitted caustics, the conditions for the development of double initial and contact caustic curves are established as functions of six independent parameters, while easy-to-use closed-form expressions are given for obtaining the contact length. An experimental protocol is then implemented in the case a thin cylindrical transparent disc is compressed between the jaws of the International Society for Rock Mechanics suggested device for the execution of the Brazilian-disc test. The experimental method of caustics can provide the contact length quite accurately, even in the case of double curves which seem that are not always a consequence of a wide contact region. KEYWORDS. Double initial and caustic curves; Compressed discs; Contact length Citation: Markides, Ch. F., Double initial and caustic curves in diametrically compressed transparent discs-Application to the contact length, Frattura ed Integrità Strutturale, 50 (2019) 451-470.

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“…The method of caustics is now recognized as an effective technique to study the stress field around the crack tip for different loading conditions. [22,23] In this method, data, which are used for calculating SIFs, are collected only in the tiny area around the crack tip and there is no need for any information pertaining to the applied force or boundary conditions. In addition, the calculation process is easier than that of any other optical method.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Dynamic Fracture Behaviors of Polymethyl Methacrylate

Gao

Zhou

2016

Macromolecular Symposia

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Summary: Dynamic fracture of polymers plays a vital role in engineering applications. Dynamic fracture behaviors of polymethyl methacrylate were studied using the optical method of caustics. Semi-circular bending specimens were chosen for mixed-mode fracture and crack interaction analysis. The crack initiation, crack propagation, stress intensity factor, and fracture toughness were obtained by analyzing the specke patterns captured during dynamic loading by high-speed imaging techniques. The crack interactions of two symmetric and asymmetric cracks and the influence of damage, including the presence of holes and microcracks on or near the crack path, are discussed. The results show that two cracks on a specimen compete and interact with each other, and lead to the final fracture mode of the specimens. Holes and microcracks on or near the crack path influence the crack path and the crack propagation velocity. The results obtained in this paper could be extended to brittle fracture analysis of materials with multiple cracks or inclusions.

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Optical method of caustics applied in viscoelastic fracture analysis

Cited by 20 publications

References 12 publications

A simple formula for calculating the tensile strength of brittle materials by means of the circular semi‐ring test and the optical method of caustics

A simple formula for calculating the tensile strength of brittle materials by means of the circular semi‐ring test and the optical method of caustics

Double initial and caustic curves in diametrically compressed transparent discs - Application to the contact length

Experimental Investigation of Dynamic Fracture Behaviors of Polymethyl Methacrylate

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