Neck Simulation | Dr Anoop Chawla



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Projects of the Simulation & Control Group (A. Chawla & S. Mukherjee)

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Repositioning Tool for FE-Human Body Model

Does your product development still follow a sequential path? Then it’s time to think!! Can you cascade your product development activities by introducing “Virtual Validation” (through finite element analysis) at concept stage of your product. Simple math will show increased benefits in the product development time through this cascading and offloading of these virtual validation activities. Computational advancements have facilitated virtual validation of not only the automobile structure but also human body models.

FE-HBM (Finite Element – Human Body Models)

Human computational models are used to investigate failures that may occur to human body under impact loads. Standard posture models that are available commercially can predict the loading in these postures. Any deviation from the standard posture is termed out-of-position (OOP) posture and is of significance in injury prediction. Some of the OOP conditions of interest are leaning or bending forward, could involve a non standard inclination of the seat back or the head positioned next to pillar and so on. Injury levels of the human body may change significantly with change in posture of the occupant. Hence it is important to evaluate the injuries to the occupant in different postures. However commercially available FE-HBMs are in a few standard postures. Repositioned models are needed to be obtained for OOP simulations. Thus, with an increasing demand for repositioned models a need to develop a repositioning tool for existing FE-HBM exist.

Steps in Repositioning

Steps in repositioning go through rigorous research and are later incorporated in a GUI based environment. The various steps in software based FE-HBM repositioning are shown. Computer graphics based methods like spines, Delaunay etc are used in repositioning techniques

Lower Extremity Repositioning

Repositioning software takes as an input FE mesh of standard human body model as shown in figure and the desired knee angle post repositioning.

(Left to Right) GM / UVA model in initial configuration. Detailed view of the knee joint region of GM / UVA model. Axis definitions.

Output from the software for various knee angles is shown in figure.

Lower extremity model (a) Initial configuration (≈ 9^O flexion) and flexed at: (b) 30^O (c) 45^O (d) 60^O (e) 75^O (f) 90^O

Repositioning Upper Extremity

Upper extremity repositioning is divided into three basic categories. Primary steps in repositioning are shown in figure below. All the steps are included in the software and with minimal inputs from the user repositioning can be done.


(a) Repositioning of lumbar and thoracic vertebra	(b) Repositioning of ribcage and associated soft tissues

Repositioning of Lumbar Spine Vertebras

Repositioning of lumbar spine is proposed to be done with natural spline technique. Repositioned spine with natural spline technique is shown.


(a) Spinal column repositioned with natural spline technique	(b) Magnified view of L5-S1 joint è change in vertebra orientation is shown

• Spine shape is changed with different thorax positions

• With flexion the lordosis of spine is decreased

Repositioning of Thoracic Spine Vertebras

Repositioning of thoracic spine is done with cubic Bezier spline technique.


(a) Thoracic spinal column repositioning with cubic Bezier	(b) Magnified view of L5-S1 joint è change in vertebra orientation is shown

Repositioning of Ribcage and Associated Soft Tissues

Post repositioning of the thorax and the lumbar spine the software automatically repositions the ribcage and associated soft tissues The output of repositioning is shown in figure below

Ribcage and soft tissues before and after repositioning

People Involved:

Faculties:

1.    Dr. A. Chawla

2.    Dr. S. Mukherjee

Students and Staff:

1.    Dhaval Jani

2.    Ratnakar Marathe

3.    Satyanarayanan RVNK

4.    Rahul Goyal

5.    Shashank

List of Sponsored Projects:

Related Publication:

1. A Chawla, S Mukherjee, D Mohan and Jain S, Validation of the cervial spine model in Thums, Proceedings of the Canadia Multidisciplinary Road Safety Conference, Ottawa, Canada, June 2004.

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