Dynamic fracture toughness determined from load-point displacement

Bacon, C.; Färm, J.; Lataillade, Jean-Luc

doi:10.1007/bf02319758

Cited by 70 publications

(47 citation statements)

References 9 publications

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“…The fracture stress can then be obtained from the force or displacement measurements. Most toughness tests designed to determine the stress intensity factor are interpreted under the assumption that the quasi-static state of equilibrium is valid, taking the analytically determined stress field in a notched specimen [15], [17].…”

Section: Introductionmentioning

confidence: 99%

A non-equilibrium approach to processing Hopkinson Bar bending test data: Application to quasi-brittle materials

Delvare

Hanus

Bailly

2010

International Journal of Impact Engineering

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International audienceThe aim of this paper was to describe a method of analysing the test data recorded during a Hopkinson Bar bending test. This three-point dynamic bending test was designed for testing the strength of materials under dynamic loads. It is carried out on a specimen consisting of a beam placed on two supports, which is subjected to an impact. The use of Hopkinson Bar as supports makes it possible to determine the forces and displacements at these points. An analytical solution for the transient response of a long beam subjected to a transverse impact was used to determine the impact force and the displacement. This procedure applies for the first few instants when the motions generated by the impact have not yet reached the supports, and the mechanical state of the specimen is identical to that of an unsupported beam. It is suitable for use with quasi-brittle materials for which failure occurs at the very beginning of the test. The material strength is determined at the time of failure, which is characterised by a sudden decrease in the bending moment. The results of a test in which a quasi-brittle material was loaded up to failure are presented and analysed as outlined above. The results obtained confirm the relevance of the present method

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Section: Introductionmentioning

confidence: 99%

A non-equilibrium approach to processing Hopkinson Bar bending test data: Application to quasi-brittle materials

Delvare

Hanus

Bailly

2010

International Journal of Impact Engineering

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“…Initially developed by Kolsky [3] to characterise metallic materials [4][5][6], this device also makes it possible to characterise other materials such as ceramics [7], concrete [8], rocks [9], composites [10] and more recently metallic cellular materials such as honeycomb or aluminium foam [11,12]. Nevertheless to characterise more compliant materials such as polymeric foams [13][14][15] or polymers [16] this apparatus has to be adapted because the impedance mismatch between polymeric cellular materials and ordinary metallic bars is too large.…”

mentioning

confidence: 99%

Polypropylene foam behaviour under dynamic loadings: Strain rate, density and microstructure effects

Bouix

Viot

Lataillade

2009

International Journal of Impact Engineering

167

125

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. Expanded polypropylene foams (EPP) can be used to absorb shock energy. The performance of these foams has to be studied as a function of several parameters such as density, microstructure and also the strain rate imposed during dynamic loading. The compressive stress-strain behaviour of these foams has been investigated over a wide range of engineering strain rates from 0.01 to 1500 s À1 in order to demonstrate the effects of foam density and strain rate on the initial collapse stress and the hardening modulus in the post-yield plateau region. A flywheel apparatus has been used for intermediate strain rates of about 200 s À1 and higher strain rate compression tests were performed using a viscoelastic SplitHopkinson Pressure Bar apparatus (SHPB), with nylon bars, at strain rates around 1500 s À1 EPP foams of various densities from 34 to 150 kg m À3 were considered and microstructural aspects were examined using two particular foams. Finally, in order to assess the contribution of the gas trapped in the closed cells of the foams, compression tests in a fluid chamber at quasi-static and dynamic loading velocities were performed.

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“…The DSIF was analyzed under the action of impact load P(t). Bacon et al [14] pointed out that under the experimental condition of three-point bending, DSIF could be obtained by the displacement response of loading point. Since the displacement of loading point is only consideration, it can be equivalent to a spring-mass system shown in Figure 1(b).…”

Section: Dynamic Stress Intensity Factor Under Impact Loadmentioning

confidence: 99%

Plastic Modifying of Dynamic Stress Intensity Factor under Impact Load

Zhang¹,

Wang²,

Li³

2017

dtetr

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Abstract. The aim of this paper is to analyze the feasibility of calculating Dynamic Stress Intensity Factor (DSIF) considering crack propagation by plastic zone. At first, the plastic zone size is calculated and the equivalent crack can be obtained. Then based on which, the DSIF subjected to the impact load is calculated. The results showed that the DSIF after plastic modifying is obviously lower than the one calculated based on linear elastic material model. Furthermore, there is a maximum value in the time history curve of DSIF. Then, the equivalent crack propagation velocity is analyzed. The result shows that when the impact load reaches the peak value, crack propagation velocity also reaches the maximum value, and so does the DSIF.

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Dynamic fracture toughness determined from load-point displacement

Cited by 70 publications

References 9 publications

A non-equilibrium approach to processing Hopkinson Bar bending test data: Application to quasi-brittle materials

A non-equilibrium approach to processing Hopkinson Bar bending test data: Application to quasi-brittle materials

Polypropylene foam behaviour under dynamic loadings: Strain rate, density and microstructure effects

Plastic Modifying of Dynamic Stress Intensity Factor under Impact Load

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