{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/101813"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/101813","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"A variational framework for mathematically nonsmooth problems in solid and structure mechanics","abstract":"DSpace SAF Submission Ingestion Package generated from Vireo submission #12823 on 2018-09-27 at 11:36:48","abstract_html":"DSpace SAF Submission Ingestion Package generated from Vireo submission #12823 on 2018-09-27 at 11:36:48","abstract_has_math":false,"creators":["Chen, Pinlei"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Civil Engineering","degree_department":null,"school":null,"contributors":["Masud, Arif","Duarte, Armando C.","Lopez-Pamies, Oscar","Geubelle, Philippe H."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-09-27T16:47:32Z","date_published":"2018-09-27T16:47:32Z","updated_at":"2026-07-22T22:24:40Z","subjects":["Variational Multiscale framework","Interfaces","Damage","Thermomechanical coupled framework","Stabilized methods","Finite strains","Discontinuous Galerkin method","Multi-constituents","Debonding","Fatigue"],"languages":["en"],"rights":["Copyright 2018 Pinlei Chen"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/101813","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Masud, Arif","Duarte, Armando C.","Lopez-Pamies, Oscar","Geubelle, Philippe H."]},{"key":"dc:creator","label":"Author","values":["Chen, Pinlei"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-09-27T16:47:32Z","2018-07-11","2018-08"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Civil Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Variational Multiscale framework","Interfaces","Damage","Thermomechanical coupled framework","Stabilized methods","Finite strains","Discontinuous Galerkin method","Multi-constituents","Debonding","Fatigue"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2018 Pinlei Chen"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/101813"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["DSpace SAF Submission Ingestion Package generated from Vireo submission #12823 on 2018-09-27 at 11:36:48","Made available in DSpace on 2018-09-27T16:47:32Z (GMT). No. of bitstreams: 2 CHEN-DISSERTATION-2018.pdf: 18516244 bytes, checksum: 948deacf4dc83dc0f451daf9220ef549 (MD5) LICENSE.txt: 4208 bytes, checksum: 98d6f6a184c377a044cb547404e6754c (MD5) Previous issue date: 2018-07-11","This dissertation presents a new paradigm for addressing multi-physics problems with interfaces in the field of Additive Manufacturing and the modeling of fibrous composite materials. The unique process of adding the material layer by layer in the AM techniques raises the issue about the stability of the interfaces between the layers and along the boundaries of multi-constituent materials. A stabilized interface formulation is developed to model debonding in monotonic loading, fatigue effects in cyclic loading, and thermal effects at interfaces which severely impact the functional life of those materials and structures. The formulation is based on embedding Discontinuous Galkerin (DG) ideas in a Continuous Galerkin (CG) framework. Starting from a mixed method incorporating the Lagrange multiplier along the interface, a pure displacement formulation is derived using the Variational Multiscale Method (VMS). From a mathematical and computational perspective, the key factor influencing the accuracy and robustness of the interface formulation is the design of the numerical flux and the penalty or stability terms. Analytical expressions that are free from user-defined parameters are naturally derived for the numerical flux and stability tensor which are functions of the evolving geometric and material nonlinearity. The proposed framework is extended for debonding at finite strains across general bimaterial interfaces. An interfacial gap function is introduced that evolves subject to constraints imposed by opening and/or sliding interfaces. An internal variable formalism is derived together with the notion of irreversibility of damage results in a set of evolution equations for the gap function that seamlessly tracks interface debonding by treating damage and friction in a unified way. Tension debonding, compression damage, and frictional sliding are accommodated, and return mapping algorithms in the presence of evolving strong discontinuities are developed. This derivation variationally embeds the interfacial kinematic models that are crucial to capturing the physical and mathematical properties involving large strains and damage. The framework is extended for monolithic coupling of thermomechanical fields in the class of problems that have embedded weak and strong discontinuities in the mechanical and thermal fields. Since the derived expressions are a function of the mechanical and thermal fields, the resulting stabilized formulation contains numerical flux and stability tensors that provide an avenue to variationally embed interfacial kinetic and kinematic models for more robust representation of interfacial physics. Representative numerical tests involving large strains and rotations, damage phenomena, and thermal effects are performed to confirm the robustness and accuracy of the method. Comparison of the results with both experimental and numerical results from literature are presented.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-08-01","The student, Pinlei Chen, accepted the attached license on 2018-07-11 at 11:37.","The student, Pinlei Chen, submitted this Dissertation for approval on 2018-07-11 at 12:09.","This Dissertation was approved for publication on 2018-07-11 at 15:25.","Embargo set by: Seth Robbins for item 107914 Lift date: 2020-09-27T16:47:41Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Open Restriction set for Item 107914 on 2018-10-16T21:28:01Z with date null by fschaef2@illinois.edu.","Open Restriction set for Item 107914 on 2018-10-16T21:28:03Z with date null by fschaef2@illinois.edu.","Open"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["A variational framework for mathematically nonsmooth problems in solid and structure mechanics"]}]}],"canonical_facts":{"dc:contributor":["Masud, Arif","Duarte, Armando C.","Lopez-Pamies, Oscar","Geubelle, Philippe H."],"dc:creator":["Chen, Pinlei"],"dc:date":["2018-09-27T16:47:32Z","2018-07-11","2018-08"],"dc:description":["DSpace SAF Submission Ingestion Package generated from Vireo submission #12823 on 2018-09-27 at 11:36:48","Made available in DSpace on 2018-09-27T16:47:32Z (GMT). No. of bitstreams: 2 CHEN-DISSERTATION-2018.pdf: 18516244 bytes, checksum: 948deacf4dc83dc0f451daf9220ef549 (MD5) LICENSE.txt: 4208 bytes, checksum: 98d6f6a184c377a044cb547404e6754c (MD5) Previous issue date: 2018-07-11","This dissertation presents a new paradigm for addressing multi-physics problems with interfaces in the field of Additive Manufacturing and the modeling of fibrous composite materials. The unique process of adding the material layer by layer in the AM techniques raises the issue about the stability of the interfaces between the layers and along the boundaries of multi-constituent materials. A stabilized interface formulation is developed to model debonding in monotonic loading, fatigue effects in cyclic loading, and thermal effects at interfaces which severely impact the functional life of those materials and structures. The formulation is based on embedding Discontinuous Galkerin (DG) ideas in a Continuous Galerkin (CG) framework. Starting from a mixed method incorporating the Lagrange multiplier along the interface, a pure displacement formulation is derived using the Variational Multiscale Method (VMS). From a mathematical and computational perspective, the key factor influencing the accuracy and robustness of the interface formulation is the design of the numerical flux and the penalty or stability terms. Analytical expressions that are free from user-defined parameters are naturally derived for the numerical flux and stability tensor which are functions of the evolving geometric and material nonlinearity. The proposed framework is extended for debonding at finite strains across general bimaterial interfaces. An interfacial gap function is introduced that evolves subject to constraints imposed by opening and/or sliding interfaces. An internal variable formalism is derived together with the notion of irreversibility of damage results in a set of evolution equations for the gap function that seamlessly tracks interface debonding by treating damage and friction in a unified way. Tension debonding, compression damage, and frictional sliding are accommodated, and return mapping algorithms in the presence of evolving strong discontinuities are developed. This derivation variationally embeds the interfacial kinematic models that are crucial to capturing the physical and mathematical properties involving large strains and damage. The framework is extended for monolithic coupling of thermomechanical fields in the class of problems that have embedded weak and strong discontinuities in the mechanical and thermal fields. Since the derived expressions are a function of the mechanical and thermal fields, the resulting stabilized formulation contains numerical flux and stability tensors that provide an avenue to variationally embed interfacial kinetic and kinematic models for more robust representation of interfacial physics. Representative numerical tests involving large strains and rotations, damage phenomena, and thermal effects are performed to confirm the robustness and accuracy of the method. Comparison of the results with both experimental and numerical results from literature are presented.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-08-01","The student, Pinlei Chen, accepted the attached license on 2018-07-11 at 11:37.","The student, Pinlei Chen, submitted this Dissertation for approval on 2018-07-11 at 12:09.","This Dissertation was approved for publication on 2018-07-11 at 15:25.","Embargo set by: Seth Robbins for item 107914 Lift date: 2020-09-27T16:47:41Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Open Restriction set for Item 107914 on 2018-10-16T21:28:01Z with date null by fschaef2@illinois.edu.","Open Restriction set for Item 107914 on 2018-10-16T21:28:03Z with date null by fschaef2@illinois.edu.","Open"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/101813"],"dc:language":["en"],"dc:rights":["Copyright 2018 Pinlei Chen"],"dc:subject":["Variational Multiscale framework","Interfaces","Damage","Thermomechanical coupled framework","Stabilized methods","Finite strains","Discontinuous Galerkin method","Multi-constituents","Debonding","Fatigue"],"dc:title":["A variational framework for mathematically nonsmooth problems in solid and structure mechanics"],"dc:type":["text"],"thesis:degree_discipline":["Civil Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:40Z"}