Tensile Fracture Toughness of Ceramic Materials: Effects of Dynamic Loading and Elevated Temperatures

Suresh, S.; Nakamura, Tsuneyoshi; Yeshurun, Y.; Yang, Kai-Chun; Duffy, J.

doi:10.1111/j.1151-2916.1990.tb07613.x

Cited by 52 publications

(32 citation statements)

References 16 publications

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“…It is concluded that the interaction between cracks and the microstructure is independent of strain rate in the investigated regions. Brokenbough et al [36] and Suresh et al [37] observed, nevertheless, an increase in fracture toughness with strain rate in ceramics K ID aK IC 1X1±1X4X Some monolithic ceramics (such as Al 2 O 3 and Si 3 N 4 ) contain intergranular glassy phases. The glassy phase can signi®cantly in¯uence the properties of the ceramic.…”

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confidence: 99%

Damage evolution in dynamic deformation of silicon carbide

et al. 2000

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AbstractÐDamage evolution was investigated in silicon carbide by subjecting it to dynamic deformation in (a) a compression Hopkinson±Kolsky bar (compressive stresses of 5 GPa), and (b) high-velocity impact under con®nement (compressive stresses of 19±32 GPa) by a cylindrical (rod) tungsten alloy projectile. Considerable evidence of plastic deformation, as dislocations and stacking faults, was found in the fractured specimens. A polytype transformation was observed through a signi®cant increase in the 6H±SiC phase at compressive stresses higher than 4.5 GPa (in the vicinity of the dynamic compressive failure strength). Profuse dislocation activity was evident in the frontal layer in the specimen recovered from the projectile impact. The formation of this frontal layer is proposed to be related to the high lateral con®ne-ment, imposed by the surrounding material. It is shown that plastic deformation is consistent with an analysis based on a ductility parameter D K C at y pc p ). The microstructural defects and their evolution were found to be dependent on the concentration of boron and aluminum, which were added as sintering aids. Several mechanisms are considered for the initiation of fracture: (a) dilatant cracks induced by mismatch in the eective elastic moduli between two adjacent grains, leading to internal tensile stresses and creating transgranular fracture. Finite element calculations show that high tensile stresses are generated due to elastic compatibility strains; (b) Zener±Stroh cracks nucleated by the piled up dislocations along grain boundaries, and resulting in intergranular fracture; (c) cracks due to existing¯aws connected with grain-boundary phases, voids, etc.; and (d) stress concentrations due to twinning and stacking faults. The high dislocation density observed in the impacted specimen is consistent with existing models of microplasticity. 7

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Damage evolution in dynamic deformation of silicon carbide

et al. 2000

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“…In order to use the dynamic G calculation for axisymmetric solids and apply the iterative scheme in a meaningful analysis, we have chosen to simulate the dynamic fracture experiment carried out by Suresh et al [8]. In their experiment, a round ceramic bar with circumferentially fatigue notched specimen was employed to determined the dynamic crack initiation toughness t(Id of various ceramics.…”

Section: Dynamic Fracture Testing Of Ceramicsmentioning

confidence: 99%

“…The record of transmitted load shows the crack initiation to occur around 14 #sec after the initial loading wave arrives at the crack region. Using the peak level of the transmitted load, the dynamic crack initiation toughness of A1203 was found to be Kid = 3.5 MPav/-m at room temperature [8]. Although the peak load was the only information needed to determined Kid, a complete transmitted load history is available from the experimental record.…”

Section: Dynamic Fracture Testing Of Ceramicsmentioning

confidence: 99%

“…A similar method has already been implemented in a plane strain interface crack analysis [7]. In this study, the iterative scheme is utilized for computational simulation of the dynamic fracture toughness testing conducted by Suresh et al [8]. In their experiment, a circumferentially notched round bar loaded by a tensile stress wave was used to determine fracture initiation toughness of ceramics and ceramic composites.…”

Section: Introductionmentioning

confidence: 99%

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Computational analysis of dynamically propagating cracks in axisymmetric solids

Nakamura

1993

Int J Fract

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Dynamic crack propagation behavior in axisymmetric solids is investigated using an effective computational procedure. First, an accurate method to extract energy release rate of a dynamically propagating crack from finite element solutions is formulated for axisymmetric geometries. The method is applied to an analysis of a radially growing circular crack under remote tension in an infinite medium. The computed dynamic energy release rate shows an excellent agreement with the exact solution. Next, we have developed an iterative technique to propagate a crack whose velocity history is initially unknown. With the iterative procedure, the crack propagates according to a condition specified by a dynamic fracture criterion. At each increment of crack growth, an optimum velocity at which the crack growth condition satisfies is obtained by the iterative scheme. This procedure requires no artificial input or no preset crack tip speed in a simulation study. The iterative scheme is employed in a dynamic fracture analysis of ceramics. The computational analysis is carded out for simulation of fracture experiments using circumferentially notched round bars. In the test, a ceramic specimen is subjected to tensile stress wave loading and after crack growth initiation, the external crack propagates to tear the specimen. The computational simulation is carded out for the entire fracture process including the crack growth initiation and the dynamic propagation. The iterative procedure enables us to predict the crack tip velocity which is unmeasurable in the experiment. Suitabilities of proposed fracture toughness criteria for the ceramics are investigated by comparing measured and computed transmitted pulses through the uncracked ligament. This study proves the usefulness of the computational procedures for dynamic fracture analysis. It is most effective in characterizing dynamic fracture toughness where determination of every relevant parameter is difficult in the experiments.

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“…Moderate fluctuations in dynamic stress intensity factor in relatively large three-point bend specimens of 75 mm height and 10 mm thickness and 89 mm height and 9.5 mm thick were documented in [3] and [4], respectively, but not to the extent shown in [1,2]. This superfluous reflected stress wave effects was eliminated by replacing the above two-dimensional fracture specimens with an one-dimensional specimen, such as that used by Duffy and his colleagues [5,6]. Despite its cleanness in test conditions, this split Hopkinson tensile bar test, which is loaded by explosives, requires special training and laboratory facilities.…”

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A bar impact tester for dynamic fracture testing of ceramics and ceramic composites

Deobald

Kobayashi

1992

Experimental Mechanics

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A bar impact test was developed to study the dynamic fracture responses of precracked ceramic bars, A1 2 0 3 and 15/29% volume SiCw/A1 2 03. Laser interferometric displacement gage data was used together with dynamic finite element analysis to determine the instantaneous crack length and the dynamic stress intensity factor, K 1 (t), in the fracturing ceramic bars impacted with impactor velocities of 5.8, 8.0, and 10 m/s. The crack velocities increased from 1400 to 2600 m/s with increasing impact velocity.The dynamic initiation fracture toughness and an increasing Ki(t) with time and with increasing impact velocity were obtained. 1.Introduction Available configurations of new ceramics and ceramic composites are often restricted to bar geometries of about 10 x 10 mm in cross section due to the historical precedence of using modulus of rupture (MOR) tests to determine the mechanical properties of early experimental materials. The MOR specimens are ideally suited for single-edge notched, three-point bend testing to determine fracture toughness despite the inherent experimental difficulties associated with such small specimens. The small three-point bend fracture specimens, however, are extremely sensitive to the interactions of reflected stress waves with the propagating crack tip as evidenced by the copious fluctuations in the dynamic stress intensity factor during the dynamic fracture process [1,2]. Moderate fluctuations in dynamic stress intensity factor in relatively large three-point bend specimens of 75 mm height and 10 mm thickness and 89 mm height and 9.5 mm thick were documented in [3] and [4], respectively, but not to the extent shown in [1,2]. This superfluous reflected stress wave effects was eliminated by replacing the above two-dimensional fracture specimens with an 2 one-dimensional specimen, such as that used by Duffy and his colleagues [5,6]. Despite its cleanness in test conditions, this split Hopkinson tensile bar test, which is loaded by explosives, requires special training and laboratory facilities. Thus a need exists for a similar clean test which can be executed without such special facilities. The objective of this paper is to describe such a dynamic fracture test procedure involving a bar impact test. Bar Impact TestThe bar impact experiment consists of a 50.8 mm long, rectangular bar specimen which is impacted on its end by a 25.4 mm long bar impactor of the same material. The reflected tension wave from the free end of the specimen bar interacts with the incoming compressive wave and generates a sharp tensile stress pulse of 3.6 gs duration in the middle of the bar specimen with the transit of approximately 3/4 of the compressive pulse as shown by the Lagrangian diagram of Fig. 1. A schematics :f the experimental apparatus is shown in Fig. 2. The specimen bar and impactor bar are held by molded urethane holders which are mounted in two carriages. Both the specimen carriage and the impactor carriage run on guide rails. An air gun propels the impactor carriage down the guide rails t...

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Tensile Fracture Toughness of Ceramic Materials: Effects of Dynamic Loading and Elevated Temperatures

Cited by 52 publications

References 16 publications

Damage evolution in dynamic deformation of silicon carbide

Damage evolution in dynamic deformation of silicon carbide

Computational analysis of dynamically propagating cracks in axisymmetric solids

A bar impact tester for dynamic fracture testing of ceramics and ceramic composites

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