{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/78570"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/78570","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Design optimization for 2-D granular media with dissipation","abstract":"We propose an optimization scheme for the tailored dynamic response through a two-dimensional packing of spherical beads. Our goal is to minimize or maximize the reaction force at the desired bead contacts. Two design approaches are presented: introducing interstitial beads and prescribing initial plastic compression in the system. Using the intruders presence or lack thereof as the design variable is a discrete optimization problem. It is necessary to make the problem tractable by convexifying the design space. The intruders presence (or non-presence) are replaced by their volume fraction. A penalty term in the cost function is used to recover the discrete design representation wherein the volume fraction converges to 0,1 values. Constraints on the design space limit the total number of intruders, which is related to the total packing weight. Designs obtained from both the elastic and the elasto-plastic material response are compared. In our second approach, we prescribe the initial plastic compression of the contact law in the beads which alters their stiffnesses. To do this the contact law is shifted by the amount of initial plastic compression and to ensure that all the beads are tightly packed, an upper bound on the initial plastic compression is imposed to limit the amount of plastic deformation between the beads. To evaluate the response, we perform a transient analysis using an explicit Runge-Kutta algorith with an adaptive time step scheme. Residual plasticity is modeled using an empirical one dimensional law that describes the history dependent contact interaction between the beads. A constitutive equation is required to evolve the state variables, i.e. the bead’s plastic deformation and large displacements are considered. Sensitivities are calculated using an adjoint method for the coupled transient analysis.","abstract_html":"We propose an optimization scheme for the tailored dynamic response through a two-dimensional packing of spherical beads. Our goal is to minimize or maximize the reaction force at the desired bead contacts. Two design approaches are presented: introducing interstitial beads and prescribing initial plastic compression in the system. Using the intruders presence or lack thereof as the design variable is a discrete optimization problem. It is necessary to make the problem tractable by convexifying the design space. The intruders presence (or non-presence) are replaced by their volume fraction. A penalty term in the cost function is used to recover the discrete design representation wherein the volume fraction converges to 0,1 values. Constraints on the design space limit the total number of intruders, which is related to the total packing weight. Designs obtained from both the elastic and the elasto-plastic material response are compared. In our second approach, we prescribe the initial plastic compression of the contact law in the beads which alters their stiffnesses. To do this the contact law is shifted by the amount of initial plastic compression and to ensure that all the beads are tightly packed, an upper bound on the initial plastic compression is imposed to limit the amount of plastic deformation between the beads. To evaluate the response, we perform a transient analysis using an explicit Runge-Kutta algorith with an adaptive time step scheme. Residual plasticity is modeled using an empirical one dimensional law that describes the history dependent contact interaction between the beads. A constitutive equation is required to evolve the state variables, i.e. the bead’s plastic deformation and large displacements are considered. Sensitivities are calculated using an adjoint method for the coupled transient analysis.","abstract_has_math":false,"creators":["Salazar De Troya, Miguel Angel"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-07-22T22:18:21Z","date_published":"2015-07-22T22:18:21Z","updated_at":"2026-07-22T22:26:11Z","subjects":["sensitivity analysis","discrete adjoint","plasticitity","granular media","optimization","adaptive time step","explicit algorithm"],"languages":["en"],"rights":["Copyright 2015 Miguel Angel Salazar De Troya"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/78570","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Salazar De Troya, Miguel Angel"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-07-22T22:18:21Z","2015-05","2015-05-01","2015-5"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"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":["sensitivity analysis","discrete adjoint","plasticitity","granular media","optimization","adaptive time step","explicit algorithm"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2015 Miguel Angel Salazar De Troya"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/78570"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["We propose an optimization scheme for the tailored dynamic response through a two-dimensional packing of spherical beads. Our goal is to minimize or maximize the reaction force at the desired bead contacts. Two design approaches are presented: introducing interstitial beads and prescribing initial plastic compression in the system. Using the intruders presence or lack thereof as the design variable is a discrete optimization problem. It is necessary to make the problem tractable by convexifying the design space. The intruders presence (or non-presence) are replaced by their volume fraction. A penalty term in the cost function is used to recover the discrete design representation wherein the volume fraction converges to 0,1 values. Constraints on the design space limit the total number of intruders, which is related to the total packing weight. Designs obtained from both the elastic and the elasto-plastic material response are compared. In our second approach, we prescribe the initial plastic compression of the contact law in the beads which alters their stiffnesses. To do this the contact law is shifted by the amount of initial plastic compression and to ensure that all the beads are tightly packed, an upper bound on the initial plastic compression is imposed to limit the amount of plastic deformation between the beads. To evaluate the response, we perform a transient analysis using an explicit Runge-Kutta algorith with an adaptive time step scheme. Residual plasticity is modeled using an empirical one dimensional law that describes the history dependent contact interaction between the beads. A constitutive equation is required to evolve the state variables, i.e. the bead’s plastic deformation and large displacements are considered. Sensitivities are calculated using an adjoint method for the coupled transient analysis.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-07-22 without embargo terms","The student, Miguel Angel Salazar De Troya, accepted the attached license on 2015-05-01 at 10:09.","The student, Miguel Angel Salazar De Troya, submitted this Thesis for approval on 2015-05-01 at 10:17.","This Thesis was approved for publication on 2015-05-01 at 10:57.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8226 on 2015-07-22 at 10:35:18","Made available in DSpace on 2015-07-22T22:18:21Z (GMT). No. of bitstreams: 2 SALAZARDETROYA-THESIS-2015.pdf: 1129765 bytes, checksum: 2a19a62b5cc8acde7b6f7461fa900d16 (MD5) LICENSE.txt: 4226 bytes, checksum: ec4d6325d191e60b338330ab014f096f (MD5) Previous issue date: 2015-05-01"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Design optimization for 2-D granular media with dissipation"]}]}],"canonical_facts":{"dc:creator":["Salazar De Troya, Miguel Angel"],"dc:date":["2015-07-22T22:18:21Z","2015-05","2015-05-01","2015-5"],"dc:description":["We propose an optimization scheme for the tailored dynamic response through a two-dimensional packing of spherical beads. Our goal is to minimize or maximize the reaction force at the desired bead contacts. Two design approaches are presented: introducing interstitial beads and prescribing initial plastic compression in the system. Using the intruders presence or lack thereof as the design variable is a discrete optimization problem. It is necessary to make the problem tractable by convexifying the design space. The intruders presence (or non-presence) are replaced by their volume fraction. A penalty term in the cost function is used to recover the discrete design representation wherein the volume fraction converges to 0,1 values. Constraints on the design space limit the total number of intruders, which is related to the total packing weight. Designs obtained from both the elastic and the elasto-plastic material response are compared. In our second approach, we prescribe the initial plastic compression of the contact law in the beads which alters their stiffnesses. To do this the contact law is shifted by the amount of initial plastic compression and to ensure that all the beads are tightly packed, an upper bound on the initial plastic compression is imposed to limit the amount of plastic deformation between the beads. To evaluate the response, we perform a transient analysis using an explicit Runge-Kutta algorith with an adaptive time step scheme. Residual plasticity is modeled using an empirical one dimensional law that describes the history dependent contact interaction between the beads. A constitutive equation is required to evolve the state variables, i.e. the bead’s plastic deformation and large displacements are considered. Sensitivities are calculated using an adjoint method for the coupled transient analysis.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-07-22 without embargo terms","The student, Miguel Angel Salazar De Troya, accepted the attached license on 2015-05-01 at 10:09.","The student, Miguel Angel Salazar De Troya, submitted this Thesis for approval on 2015-05-01 at 10:17.","This Thesis was approved for publication on 2015-05-01 at 10:57.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8226 on 2015-07-22 at 10:35:18","Made available in DSpace on 2015-07-22T22:18:21Z (GMT). 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