Mechanics of hard and soft tissue

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PRITI prajapati : 

PRITI prajapati Mechanics of hard and soft tissue

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Hard Tissue Hard tissue refers to tissue that has become mineralised, tissue having a firm intercellular substance. In humans, some of the hard tissues include skeletal bones cartilages Bone In other animals, they include Antlers Ivories horns shells

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Soft Tissue Soft tissue is a term that refers to structures of the body that connect, envelope, support and/or move the structures around it. Examples of soft tissue include: Tendons Ligaments Fascia Skin fibrous tissues fat synovial membranes

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Tissue biomechanics Living bone has the ability to adapt its properties to the change of mechanical load environment. An augmentation of physical activities such as running significantly increases the bone formation and mineralization whereas a long-term disuse of the skeleton involves inhibition of bone formation and induces significant demineralization of bone.

Intracortical bone remodeling : Density evolution during training and detraining: 

Intracortical bone remodeling : Density evolution during training and detraining In everyday activities, viscosity of  soft tissues as ligaments, tendons, and arteries, is observed. Stress depends on strain rate, and on the history of deformations. The influence of strain history is one of the main caracteristics of biological tissues.

Typical relaxation function of human ACL, PCL, tendons: 

Typical relaxation function of human ACL, PCL, tendons Hard tissue and soft tissue biomechanics are investigated by means of continuum models undergoing non linear strains.

Mechanical Characteristics : 

Mechanical Characteristics At small strains , elastin confers stiffness to the tissue and stores most of the strain energy . The collagen fibers are comparatively inextensible and are usually loose (wavy,crimped). With increasing tissue deformation the collagen is gradually stretched in the direction of deformation. When taut, these fibers produce a strong growth in tissue stiffness. The composite behavior is analogous to a nylon stocking , whose rubber band does the role of elastin as the nylon does the role of collagen. In soft tissues the collagen limits the deformation and protects the tissues from injury.

Figure 1: Graph of lagrangian stress (T) versus stretch ratio (λ) of a preconditioned soft tissue. : 

Figure 1: Graph of lagrangian stress (T) versus stretch ratio (λ) of a preconditioned soft tissue . Soft tissues have the potential to undergo big deformations and still come back to the initial configuration when unloaded. The stress-strain curve is nonlinear , as can be seen in Figure 1. The soft tissues are also viscoelastic , incompressible and usually anisotropic . Some viscoelastic properties observable in soft tissues are: relaxation , creep and hysteresis .

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