Related Experiment Video
Updated: Jun 30, 2026
14:14
Quantification of Strain in a Porcine Model of Skin Expansion Using Multi-View Stereo and Isogeometric Kinematics
Published on: April 16, 2017
Nonlinear elastic-viscoplastic constitutive equations for aging facial tissues
1Institute of Mechanical Systems ETH, 8092 Zurich, Switzerland. edoardo.mazza@imes.mavt.ethz.ch
Biomechanics and Modeling in Mechanobiology
|August 13, 2005
Summary
This study simulates facial aging using a finite element model, showing how tissue stiffness loss and gravity cause soft tissue descent over 30 years.
Area of Science:
- Biomechanics
- Computational modeling
- Dermatology
Background:
- Human facial structure comprises multilayered tissues with distinct mechanical properties.
- Facial aging involves changes in tissue stiffness and response to long-term forces like gravity.
- Understanding these changes is crucial for cosmetic and reconstructive applications.
Purpose of the Study:
- To simulate the nonlinear mechanical behavior of an aging human face.
- To model the effects of aging and gravitational forces on facial soft tissues.
- To develop a computational framework for predicting age-related facial deformations.
Main Methods:
- A finite element model (FEM) was developed using the 3D facial geometry.
- Constitutive properties of facial tissues were incorporated into the FEM.
- An aging function was introduced to model the loss of elastic stiffness over time.
- Simulations were performed for 30 years of gravitational exposure.
Main Results:
- The simulation successfully modeled progressive gravimetric soft tissue descent.
- Calculations showed deformations and stress distributions within facial soft tissue layers.
- The results indicate a loss of tissue stiffness contributing to visible aging signs.
Conclusions:
- The finite element model provides a framework for simulating facial aging.
- Gravitational forces significantly influence soft tissue descent over decades.
- The study highlights the interplay between tissue mechanics, aging, and facial structure changes.
Related Concept Videos
01:21Plastic Behavior
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and reloaded.
01:22Generalized Hooke's Law
The generalized Hooke's Law is a broadened version of Hooke's Law, which extends to all types of stress and in every direction. Consider an isotropic material shaped into a cube subjected to multiaxial loading. In this scenario, normal stresses are exerted along the three coordinate axes. As a result of these stresses, the cubic shape deforms into a rectangular parallelepiped. Despite this deformation, the new shape maintains equal sides, and there is a normal strain in the direction of the...
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
Deformation occurs in axial and transverse directions when an axial load is applied to a slender bar. This deformation impacts the cubic element within the bar, transforming it into either a rectangular parallelepiped or a rhombus, contingent on its orientation. This transformation process induces shearing strain. Axial loading elicits both shearing and normal strains. Applying an axial load instigates equal normal and shearing stresses on elements oriented at a 45° angle to the load axis.
01:19Members Made of Elastoplastic Material
The behavior of elastoplastic materials under bending stresses, particularly in structural members with rectangular cross-sections, is crucial for predicting material responses and understanding failure modes. Initially, when a bending moment is applied, the stress distribution across the section follows Hooke's Law and is linear and elastic. This distribution means the stress increases from the neutral axis to the maximum at the outer fibers, up to the elastic limit.
As the bending moment...
As the bending moment...
01:18Residual Stresses in Bending
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...
01:20Elastic Strain Energy for Shearing Stresses
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...