title: Constant strain rate compression of bovine cortical bone on the Split-Hopkinson Pressure Bar.
abstract: Cortical bone is a visco-elastic material which implies that strain rate will affect its response. Although the Split-Hopkinson Pressure Bar is an accepted technique for determining the dynamic compressive properties of cortical bone it has been shown that the strain rate of compression does not remain constant throughout the duration of a classical experiment with a uniform striker. This raises concerns as to the measurement of smeared responses. This paper presents a shaped striker technique whereby the incident pulse can be shaped to attain a constant strain rate experiment for bovine bone. Shaped strikers offer benefits such as re-usability and increased test repeatability. A comparison of the stress-strain-strain rate responses attained through classical and constant strain rate experiments shows that the shape of the stress-strain curves from conventional experiments is adversely affected in the portion where the strain rate varies. The dynamic response corridors for the two tests are similar, however the ultimate properties are affected. It is concluded that the strain rate history should be presented with dynamic stress-strain responses since the instantaneous strain rate is a likely contributor to potential constitutive models.
authors.affiliation: Blast Impact and Survivability Research Unit, Department of Mechanical Engineering, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa; Department of Mechanical and Mechatronic Engineering, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa. Electronic address: annieb@sun.ac.za.
authors.forename: A
authors.initials: A
authors.lastname: Bekker
authors.affiliation: Blast Impact and Survivability Research Unit, Department of Mechanical Engineering, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
authors.forename: T J
authors.initials: TJ
authors.lastname: Cloete
authors.affiliation: Department Biological Sciences, Private Bag X3, Rondebosch 7701, South Africa.
authors.forename: A
authors.initials: A
authors.lastname: Chinsamy-Turan
authors.affiliation: Blast Impact and Survivability Research Unit, Department of Mechanical Engineering, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
authors.forename: G N
authors.initials: GN
authors.lastname: Nurick
authors.affiliation: Blast Impact and Survivability Research Unit, Department of Mechanical Engineering, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa; Department of Mechanical and Aeronautical Engineering, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa.
authors.forename: S
authors.initials: S
authors.lastname: Kok
mesh_terms: D000818:Animals; D002417:Cattle; D005269:Femur / Q000502:physiology*; D013314:Stress, Mechanical
keywords: Bovine cortical bone; Compression; Pressure bar; Shaped striker; Split-Hopkinson; Strain rate effects