Novel approaches to the structural integrity assessment of acrylic bone cement as part of the bone/cement/stem construct
Novel approaches to the structural integrity assessment of acrylic bone cement as part of the bone/cement/stem construct
No consensus exists for the use of a standard procedure when determining bone cement fatigue properties and a robust method for bone cement failure characterisation would therefore be beneficial. This study attempts to address this requirement by: (i) implementing the acoustic emission (AE) technique for bone cement failure assessment, (ii) developing a methodology for a more accurate and comprehensive representation of bone cement fatigue behaviour and (iii) developing an experimental method for measurement of the stresses induced during polymerisation of the cement.
The ability of the AE technique to detect damage in the bone cement is demonstrated. Under fatigue bending loads, damage was located and monitored in real time. The results support the damage accumulation scenario as cracks were detected at various locations in the tested specimens. The acoustic signals corresponding to bone cement failure were characterised and critical acoustic events associated with bone cement damage were identified. The AE parameters emitted during crack growth were shown to vary with ageing condition: acoustic signals of longer rise time and lower duration were emitted during failure of specimens aged and tested in Ringer’s solution at 37°C compared to specimens aged in air at room temperature. This illustrates a more gradual energy release for the former specimens and is indicative of plasticisation of the matrix. During fatigue failure, the AE sequence consisted of bursts of emissions, separated by periods of silence, suggesting that the processes involved during crack growth were discontinuous. In addition, periods of rest (i.e. when the sample was unloaded) proved to be deleterious as there was an AE burst on reloading.
The crack growth behaviour in vacuum mixed CMW1 under flexural loads was further characterised. An SN curve was obtained and the endurance limit of the cement was established. The SN data were analysed statistically using a Weibull 3 parameters method; from this, it was possible to propose a probability of failure versus stress level relationship for the cement. The viscoelastic nature of the cement was demonstrated using hysteresis and creep data obtained during cyclic loading. Relationships were identified between the stress level and (i) the total accumulated hysteresis damage and (ii) the hysteresis per cycle. Further, the viscoelastic behaviour of the cement was accurately represented by a Maxwell element.
Finally, the generation of stresses during and post curing was analysed to determine the initial conditions of stress in the construct. Significant residual stresses were present in the cement two hours post implantation. Stress relief mechanisms were demonstrated using the AE technique.
University of Southampton
Roques, Anne
5560237b-df68-492e-a4a9-0a075eaf104b
2003
Roques, Anne
5560237b-df68-492e-a4a9-0a075eaf104b
Roques, Anne
(2003)
Novel approaches to the structural integrity assessment of acrylic bone cement as part of the bone/cement/stem construct.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
No consensus exists for the use of a standard procedure when determining bone cement fatigue properties and a robust method for bone cement failure characterisation would therefore be beneficial. This study attempts to address this requirement by: (i) implementing the acoustic emission (AE) technique for bone cement failure assessment, (ii) developing a methodology for a more accurate and comprehensive representation of bone cement fatigue behaviour and (iii) developing an experimental method for measurement of the stresses induced during polymerisation of the cement.
The ability of the AE technique to detect damage in the bone cement is demonstrated. Under fatigue bending loads, damage was located and monitored in real time. The results support the damage accumulation scenario as cracks were detected at various locations in the tested specimens. The acoustic signals corresponding to bone cement failure were characterised and critical acoustic events associated with bone cement damage were identified. The AE parameters emitted during crack growth were shown to vary with ageing condition: acoustic signals of longer rise time and lower duration were emitted during failure of specimens aged and tested in Ringer’s solution at 37°C compared to specimens aged in air at room temperature. This illustrates a more gradual energy release for the former specimens and is indicative of plasticisation of the matrix. During fatigue failure, the AE sequence consisted of bursts of emissions, separated by periods of silence, suggesting that the processes involved during crack growth were discontinuous. In addition, periods of rest (i.e. when the sample was unloaded) proved to be deleterious as there was an AE burst on reloading.
The crack growth behaviour in vacuum mixed CMW1 under flexural loads was further characterised. An SN curve was obtained and the endurance limit of the cement was established. The SN data were analysed statistically using a Weibull 3 parameters method; from this, it was possible to propose a probability of failure versus stress level relationship for the cement. The viscoelastic nature of the cement was demonstrated using hysteresis and creep data obtained during cyclic loading. Relationships were identified between the stress level and (i) the total accumulated hysteresis damage and (ii) the hysteresis per cycle. Further, the viscoelastic behaviour of the cement was accurately represented by a Maxwell element.
Finally, the generation of stresses during and post curing was analysed to determine the initial conditions of stress in the construct. Significant residual stresses were present in the cement two hours post implantation. Stress relief mechanisms were demonstrated using the AE technique.
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Published date: 2003
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Local EPrints ID: 465439
URI: http://eprints.soton.ac.uk/id/eprint/465439
PURE UUID: fa5d23cf-560a-4f01-afbd-14a4c6bdbeb2
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Date deposited: 05 Jul 2022 01:02
Last modified: 16 Mar 2024 20:11
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Author:
Anne Roques
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