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Soft Tissue Mechanics Viscoelasticity

EiM-5 Soft Tissue Mechanics (3). Lecture Overview. Reprise on Soft Tissue PropertiesEngineering MaterialsElastic Materials and Viscous FluidsViscoelasticityLinear viscoelasticityKelvin modelMaxwell modelVignette on spider's silk. EiM-5 Soft Tissue Mechanics (3). Langer Lines. The orientation

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Soft Tissue Mechanics Viscoelasticity

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    1. EiM-5 Soft Tissue Mechanics (3) Soft Tissue Mechanics & Viscoelasticity …or why you don’t wobble like a jelly when you run.

    2. EiM-5 Soft Tissue Mechanics (3) Lecture Overview Reprise on Soft Tissue Properties Engineering Materials Elastic Materials and Viscous Fluids Viscoelasticity Linear viscoelasticity Kelvin model Maxwell model Vignette on spider’s silk

    3. EiM-5 Soft Tissue Mechanics (3) Langer Lines The orientation in which skin will cleave when struck with a spike. Useful for forensic science. Suggest incision orientation for minimal scarring.

    4. EiM-5 Soft Tissue Mechanics (3) Soft Tissue Properties Collagen crimp/waveform straightening Collagen triple helix collapse and then axial stretch Fluid egress from structure Role of GAGs in holding water contentCollagen crimp/waveform straightening Collagen triple helix collapse and then axial stretch Fluid egress from structure Role of GAGs in holding water content

    5. EiM-5 Soft Tissue Mechanics (3) Soft Tissue Properties

    6. EiM-5 Soft Tissue Mechanics (3) Engineering Materials Linear elasticity Hooke’s Law Appropriate assumption for many materials Many engineering materials can be assumed to be Hookean for small strains. In reality all materials are non-Hookean.Many engineering materials can be assumed to be Hookean for small strains. In reality all materials are non-Hookean.

    7. EiM-5 Soft Tissue Mechanics (3) Engineering Materials Linear viscous fluids Newtonian fluids Non-Newtonian

    8. EiM-5 Soft Tissue Mechanics (3) Engineering Materials Comparing elastic & viscous response

    9. EiM-5 Soft Tissue Mechanics (3) Viscoelasticity Three characteristic behaviours observed:

    10. EiM-5 Soft Tissue Mechanics (3) Linear Viscoelasticity Constitutive models: Kelvin-Voigt solid model

    11. EiM-5 Soft Tissue Mechanics (3) Linear Viscoelasticity Constitutive models: Maxwell fluid model

    12. EiM-5 Soft Tissue Mechanics (3) Linear Viscoelasticity Constitutive models: 3-parameter solid model

    13. EiM-5 Soft Tissue Mechanics (3) Linear Viscoelasticity Constitutive models: 3-parameter liquid model

    14. EiM-5 Soft Tissue Mechanics (3) Linear Viscoelasticity Constitutive models: it can all get too much! Maxwell-Weichert models Kelvin Chain Models

    15. EiM-5 Soft Tissue Mechanics (3) Four common types of tensile materials are found in living organisms: silk, collagen, cellulose, and chitin. Silk and collagen are both composed of proteins, while cellulose and chitin are composed of polysaccharides (sugars). Questions: How does the spider know to make a web?? (outside this course!) How does the web of a spider balance the conflicting requirements of being strong enough to trap prey, fine enough to resist wind disturbance, and flexible enough to resist deformation from struggling insects and movement of anchoring substrate? How does the spider spin with something that is so strong?Four common types of tensile materials are found in living organisms: silk, collagen, cellulose, and chitin. Silk and collagen are both composed of proteins, while cellulose and chitin are composed of polysaccharides (sugars). Questions: How does the spider know to make a web?? (outside this course!) How does the web of a spider balance the conflicting requirements of being strong enough to trap prey, fine enough to resist wind disturbance, and flexible enough to resist deformation from struggling insects and movement of anchoring substrate? How does the spider spin with something that is so strong?

    16. EiM-5 Soft Tissue Mechanics (3) Mechanical properties impressive. How are these achievedMechanical properties impressive. How are these achieved

    17. EiM-5 Soft Tissue Mechanics (3)

    18. EiM-5 Soft Tissue Mechanics (3) Mechanical properties impressive. How are these achievedMechanical properties impressive. How are these achieved

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