Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form

A Nonlinear and Inelastic Constitutive Equation for Human Cerebral Arterial and Aneurysm Walls

Wulandana, Rachmadian (2003) A Nonlinear and Inelastic Constitutive Equation for Human Cerebral Arterial and Aneurysm Walls. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

Primary Text

Download (1MB) | Preview


The underlying motivation of this work is the desire to understand better the formation and development of cerebral saccular aneurysm, lesions frequently found at the apex of bifurcations in and near the Circle of Willis. Degradation of elastin, which is one important passive mechanical component of arterial walls, has been hypothesized to play a role in aneurysm formation. This hypothesis has been motivated by the aneurysm wall histology that always displays fragmented elastin.Currently there is no single appropriate constitutive equation for both cerebral arterial and aneurysm walls. Available constitutiveequations are directed at modeling the nonlinear behavior of cerebral arterial tissue that is hypothesized to arise from recruitment of collagen (another important passive biomechanicalcomponent of arterial wall) but not the inelastic behavior that is hypothesized to be due to elastin fragmentation.In this work, we propose a constitutive equation that is capable of handling both the nonlinearity and inelasticity. Thisconstitutive equation, unlike the classical single mechanism elastic constitutive relation, employs two mechanisms. The first and second mechanisms represent the mechanical response ofelastin and collagen, respectively. The collagen recruitment is modeled by introducing the second mechanism at a specified deformed state, while the elastin breakage is modeled by deactivating the first mechanism at a later deformed state.Moreover, we discuss applications of the new constitutive equation in some relevant problems. For example, we discuss the inflationof a cylindrical membrane and compare analytical results to existing experimental data that demonstrates both the nonlinear and inelastic behavior of cerebral arterial walls and use the data to obtain material constants for the new constitutive equation.The presentation of this work is intended to introduce a new approach that can be used to incorporate various biological mechanisms that have been hypothesized to be involved in aneurysmformation and development. Indeed the current work involves only two important mechanisms, but theoretically the current model can be generalized easily to include more mechanisms if necessary to represent gradual recruitment and breakage.


Social Networking:
Share |


Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairRobertson, Anne Mannerob@engr.pitt.eduRBERTSON
Committee MemberVorp, David
Committee MemberSacks, Michael
Committee MemberSlaughter, William
Committee MemberGaldi, Giovanni
Committee MemberYonas,
Date: 3 September 2003
Date Type: Completion
Defense Date: 18 June 2003
Approval Date: 3 September 2003
Submission Date: 6 August 2003
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: cerebral arteries; constitutive equations; inelastic; multi-mechanism; nonlinear; saccular aneurysms
Other ID:, etd-08062003-005342
Date Deposited: 10 Nov 2011 19:57
Last Modified: 15 Nov 2016 13:48


Monthly Views for the past 3 years

Plum Analytics

Actions (login required)

View Item View Item