Fracture Toughness, Dynamic

A. S. Kobayashi, A. F. Emery, and B. M. Liaw Dynamic Fracture Toughness of Reaction Bonded Silicon Nitride, Journal of the American Ceramic Society, 66[2], 151-155 (1983). 

Rapid crack propagation, dynamic fracture toughness, crack arrest, polyethylene pipes, pressure vessels... 

Der, V.K., Holloway, D.C. and Kobayashi, T. (1978). Techniques for Dynamic Fracture Toughness Measurements. Prepared for the National Science Foundation by Photomechanics Laboratory, Mechanical Engineering Department, University of Maryland, College Park Campus. 

The dynamic fracture toughness, Ksimplified equation (2) proposed in [10] ... 

Fig. 9 Loading rate dependence of quasi-static fracture toughness values, determined by an FBA method and dynamic fracture toughness values, Kj, determined by the DKC method for Charpy type fracture specimens of (a) PC and (b) POM.

At even higher loading rates, for which no valid force-time signal for applying an FBA data reduction scheme can be recorded, the DKC-method may be used to determine dynamic fracture toughness values, Kj. This requires an adequate technique to measure the time-to-... 

This approach does not address the higher frequency effects so an improved mass spring model has been proposed by Williams et al [8]. The calculation is somewhat cumbersome and for practical purposes has to be solved using a mathematics package such as MATHCAD. This improved model is used in this paper to calculate both the dynamic fracture toughness Kj and the dynamic fracture energy Gd. 

Fig 8. Dynamic fracture toughness (from MSM and DKC) and fracture energy for PMMA... 

Instrumented Charpy impact tests on unnotched samples are conducted to determine the energy absorbing capability and dynamic fracture behaviour of the C/SiC composites. The dynamic fracture toughness (ak) is calculated using the following equation ... 

SZABO J S., CZIGANY T., Investigation of static and dynamic fracture toughness of short ceramic fiber reinforced PP composites, J. Macromol. Sci., B41, 1191-1204, 2002. 

Dynamic tests were conducted on bend specimens using an instrumented drop-weight test machine. The specimens were prepared and the results evaluated, as recommended in ASTM E399 for static bend specimens. The Ko (dynamic fracture toughness) values were calculated from the maximum load on the instrumented drop weight tup. A soft steel half-round pad was used between the specimen and the tup, so that load rise times were 1 to 2 msec and inertial effects were not significant. 

Kc = non-plane-strain fracture toughness based on maximum load Kd = dynamic fracture toughness Kic = plane strain fracture toughness Pc = critical load in fracture toughness test S = bend specimen span Vc = critical clip gauge opening displacement W = specimen width Y = specimen calibration function... 

Figure 58. Fracture surface after dynamic fracture toughness test.

Mar Marur, P. R., Batra, R. C., Garcia, G., Loos, A. C. Static and dynamic fracture toughness of epoxy/alumina composite with submicron inclusimis. J. Mater. Sci. 39 (2004) 1437-1440. 

Kjjj is the critical dynamic fracture toughness, and B is the section thickness, all in consistent units. 

Effects of irradiation on dynamic fracture toughness and crack-arrest toughness... 

In comparison with initiation fracture toughness data, there are substantially fewer data on effects of irradiation on dynamic fracture toughness and crack-arrest toughness. Some early results of vs temperature are shown in Fig. 10.11 (Davidson et al, 1976), while more recent results of Ki are shown in Fig. 10.12 (Iskander et al, 1992). In general, the... 

Plot from the 1970s showing effects of irradiation on dynamic fracture toughness, ffid, vs temperature (Davidson et al., 1976). 

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