Aging and loading rate effects on the mechanical behavior of equine bone

Kulin, Robb M.; Jiang, Fengchun; Vecchio, Kenneth S.

doi:10.1007/s11837-008-0069-0

Cited by 16 publications

(11 citation statements)

References 31 publications

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“…This difference in R-curve slope values suggests a sharp reduction and/or absence of toughening mechanisms in bone during high strain rates such as these associated with traumatic fracture conditions. This agrees well with: (1) the smooth fracture surface profiles observed in specimens tested under high loading rates (Behiri and Bonfield, 1980; Adharapurapu et al, 2006; Zioupos et al, 2006; Kulin et al, 2008); (2) the good positive correlations we have observed here between the experimentally measured microcrack number and the fracture toughness found in our simulations; (3) the previous study by Vashishth et al, (1997) which demonstrated that increased microcracking leads to higher bone toughness; (4) the experimental observations by Kulin et al (2008, 2010, 2011) that bone subjected to quasi-static loading undergoes significant peripheral damage during crack propagation whereas bone subjected to dynamic loading did not exhibit a large amount of damage; (5) the observations by Zioupos et al (2008) that the key to bone s brittleness in high strain rates is the strain and damage localization occurring early on in the process, which leads to low post-yield strains, low energy absorption to failure and less collateral damage alongside the fracture front.…”

Section: Discussionsupporting

confidence: 89%

“…For example, using quasi-static conditions, some of the earlier studies done on bovine or equine bone reported an increase in initiation fracture resistance measured as energy absorption or critical stress intensity factor with increasing strain rates up to a certain level after which a decrease was observed (Piekarski, 1970; Crowninshield and Pope, 1974; Robertson and Smith, 1978; Behiri and Bonfield, 1980, 1984; Evans et al, 1992). More recent investigations also reported similar trends where fracture toughness in bovine and equine bone (Adharapurapu et al, 2006; Charoenphan and Polchai, 2007; Kulin et al, 2008; Kulin et al, 2010; Kulin et al, 2011) and energy to fracture in human cortical bone (Zioupos et al, 2008) decreased with increasing strain rate. The only study that measured the propagation toughness at a high strain rate reported the loading rate effects on the R-curve behavior of equine cortical bone (Kulin et al, 2010).…”

Section: Introductionsupporting

confidence: 57%

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The effect of strain rate on fracture toughness of human cortical bone: A finite element study

Ural

Zioupos

Buchanan

et al. 2011

Journal of the Mechanical Behavior of Biomedical Materials

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Evaluating the mechanical response of bone under high loading rates is crucial to understanding fractures in traumatic accidents or falls. In the current study, a computational approach based on cohesive finite element modeling was employed to evaluate the effect of strain rate on fracture toughness of human cortical bone. Two-dimensional compact tension specimen models were simulated to evaluate the change in initiation and propagation fracture toughness with increasing strain rate (range: 0.08 to 18 s−1). In addition, the effect of porosity in combination with strain rate was assessed using three-dimensional models of microcomputed tomography-based compact tension specimens. The simulation results showed that bone’s resistance against the propagation of fracture decreased sharply with increase in strain rates up to 1 s−1 and attained an almost constant value for strain rates larger than 1 s−1. On the other hand, initiation fracture toughness exhibited a more gradual decrease throughout the strain rates. There was a significant positive correlation between the experimentally measured number of microcracks and the fracture toughness found in the simulations. Furthermore, the simulation results showed that the amount of porosity did not affect the way initiation fracture toughness decreased with increasing strain rates, whereas it exacerbated the same strain rate effect when propagation fracture toughness was considered. These results suggest that strain rates associated with falls lead to a dramatic reduction in bone’s resistance against crack propagation. The compromised fracture resistance of bone at loads exceeding normal activities indicates a sharp reduction and/or absence of toughening mechanisms in bone during high strain conditions associated with traumatic fracture.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionsupporting

confidence: 57%

The effect of strain rate on fracture toughness of human cortical bone: A finite element study

Ural

Zioupos

Buchanan

et al. 2011

Journal of the Mechanical Behavior of Biomedical Materials

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“…After the specimen was loaded, the displacement was increased by increments of 0.0127 mm (0.0005 in.). It is recognized that a load rate has an impact on the fracture toughness [10] and is important in the study of relaxation and changes in response. Therefore, the duration of the manual increments in the displacements was carefully monitored with a timer.…”

Section: Testsmentioning

confidence: 99%

“…These range from the specimen geometry [9], loading rate [10], temperature during testing [11], age [12], orientation [13], and location [14], to the preservation method. Yan et al [11] found that fracture toughness decreases with the increase in temperature.…”

Section: Introductionmentioning

confidence: 99%

Influence of Storage Duration on Retention of Original Fracture Toughness

et al. 2010

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Accurate knowledge of bone properties is central in the prediction of failure and the development of injury treatment protocols. Often when bone properties are measured experimentally, bone specimens have to be chemically preserved prior to or during testing. Understanding the effect of the bone preservation method on the material properties is important. Degradation of properties due to preservation methods may lead to incorrect reporting of values of the bone properties. A salient question is, therefore, whether the preservation of bovine cortical bone in ethanol for extended periods of time affects fracture toughness; and if so, whether that affect is reversible. To answer these questions, a three-point bending test set-up was constructed to perform experiments over a period of 9 weeks. A total of 109 specimens of cortical bone of the same orientation were manufactured from the middiaphysis of the femur. These specimens were separated into three groups based on location in the femur; namely, medial, lateral, and posterior. The specimens were preserved in ethanol. At the end of each week, a sample of specimens was selected for testing, with the last sample tested after 9 weeks of preservation. It was shown that after 9 weeks of preservation in ethanol, followed by rehydration with physiological saline, the fracture toughness of the specimen was unchanged from that of the control specimen. Omission of rehydration in saline resulted in to an increased fracture toughness of up to 17%.

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“…Experimental studies show that the fracture behavior of bone changes with loading rate (Behiri and Bonfield, 1980, 1984; Evans et al, 1992; Adharapurapu et al, 2006; Hansen et al, 2008; Kulin et al, 2008; Zioupos et al, 2008; Kulin et al, 2011a; Kulin et al, 2011b; Ural et al, 2011). Consequently, fracture risk may be underestimated due to an overestimation of the fracture load if the strain rate effects are not considered.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the influence of strain rate on Colles' fracture load

Ural¹,

Zioupos²,

Buchanan³

et al. 2012

Journal of Biomechanics

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Colles’ fracture, a transverse fracture of the distal radius bone, is one of the most frequently observed osteoporotic fractures resulting from low energy or traumatic events, associated with low and high strain rates, respectively. Although experimental studies on Colles’ fracture were carried out at various loading rates ranging from static to impact loading, there is no systematic study in the literature that isolates the influence of strain rate on Colles’ fracture load. In order to provide a better understanding of fracture risk, the current study combines experimental material property measurements under varying strain rates with computational modeling and presents new information on the effect of strain rate on Colles’ fracture. The simulation results showed that the Colles’ fracture load decreased with increasing strain rate with a steeper change in lower strain rates. Specifically, strain rate values (0.29 s−1) associated with controlled falling without fracture corresponded to a 3.7% reduction in the fracture load. On the other hand, the reduction in the fracture load was 34% for strain rate of 3.7 s−1 reported in fracture inducing impact cadaver experiments. Further increase in the strain rate up to 18 s−1 lead to an additional 22% reduction. The most drastic reduction in fracture load occurs at strain rates corresponding to the transition from controlled to impact falling. These results are particularly important for the improvement of fracture risk assessment in the elderly because they identify a critical range of loading rates (10–50 mm/s) that can dramatically increase the risk of Colles’ fracture.

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Aging and loading rate effects on the mechanical behavior of equine bone

Cited by 16 publications

References 31 publications

The effect of strain rate on fracture toughness of human cortical bone: A finite element study

The effect of strain rate on fracture toughness of human cortical bone: A finite element study

Influence of Storage Duration on Retention of Original Fracture Toughness

Evaluation of the influence of strain rate on Colles' fracture load

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