{"id":{"repo_id":"greece","oai_identifier":"oai:10442/1193"},"canonical_url":"https://search.dev.ndltd.org/etd/greece/oai:10442/1193","repository":{"repo_id":"greece","name":"Greek National Archive of PhD Theses","base_url":"https://phdtheses.ekt.gr/eadd_oai/request"},"display":{"title":"ΓΕΝΙΚΕΥΜΕΝΑ ΚΡΙΤΗΡΙΑ ΑΣΤΟΧΙΑΣ ΑΡΧΙΚΩΣ ΑΝΙΣΟΤΡΟΠΩΝ ΕΛΑΣΤΙΚΩΝ ΜΕΣΩΝ ΜΕ ΙΔΙΑΙΤΕΡΗ ΕΜΦΑΣΗ ΣΤΑ ΣΥΝΘΕΤΑ ΥΛΙΚΑ","abstract":"THE \"ELASTIC STRUCTURE\" OF LINEARLY ELASTIC ANISOTROPIC MEDIA WAS STUDIED IN TERMS OF SPECTRAL ANALYSIS THEORY OF 4TH RANK SYMMETRIC TENSORS. BY MEANS OF THE SPECTRAL DECOMPOSITION OF THE TRANSVERSELY ISOTROPIC COMPLIANCE TENSOR, ITS EIGENVALUES AND EIGENTENSORS WERE EXPLICITY DEFINED. IT WAS SHOWN THAT THESE EIGENTENSORS DECOMPOSE THE STRAIN ENERGY DENSITY OF TRANSVERSELY ISOTROPIC MEDIA IN WELL DEFINED PARTS ASSOCIATED WITH EIGENDEFORMATION STATES OF THE MEDIUM, AND AN INTERESTING GEOMETRIC INTERPRETATION WAS GIVEN FOR THESE ELASTIC EIGENSTATES.BY GENERALIZING THE CHARACTERIZATION OF ELASTIC SYMMETRY, THE INFLUENCE OF ORTHOTROPIC COMPLIANCE TENSOR COMPONENTS ON THE INCLUDED STRESS FIELD OF PLANE STRESS PROBLEMS WAS STUDIED. BY CALCULATING THE STRESS FIELD IN THE VICINITY OF ANELLIPTIC CUT OF AN ORTHOTROPIC PLATE, AS WELL AS THE STRESS CONCENTRATION INDUCED ON ITS BOUNDARY, IT WAS PROVED THAT FOR A SPECIFIC COUPLING OF THE COMPLIANCE TENSOR COMPONENTS, THE STRESS CONCENTRATION FACTOR TAKES MINIMUM VALUES. THUS, IT IS PROVED THAT IT IS POSSIBLE TO QUANTITATIVELY CORRELATE FRACTURE TOUGHNESS CHARACTERIZATION OF AN ANISOTROPIC LINEAR ELASTIC MEDIUM WITH THE VALUE OF ITS COMPLIANCE TENSOR COMPONENTS. IN THE SEQUEL, THE ISOTROPIC CRITERION OF THEPARABOLOIDAL FAILURE SURFACE OF REVOLUTION WAS GENERALIZED IN ORDER TO PREDICTFAILURE OF ANISOTROPIC MEDIA, AND EXTREMUM PROPERTIES OF THE FAILURE FUNCTION WERE STUDIED IN A GENERALIZED TENSOR INVARIANT FORM. VARIOUS FEATURES OF THE FAILURE CRITERION WERE STUDIED IN DETAIL AND COMPARISON OF ITS THEORETICAL PREDICTIONS WITH EXPERIMENTAL DATA, ESPECIALLY FROM FAILURE TESTS OF FIBER COMPOSITES, PROVED ITS CORRECTNESS. FINALLY, THE GENERALIZATION OF THE ELLIPTIC PARABOLOID FAILURE CRITERION FOR THE GENERALLY ANISOTROPIC ELASTIC SOLID WAS ATTEMPTED FOR THE CASE THAT HYDROSTATIC COMPRESSION IS NOT A SAFE LOADING ANYMORE, BUT SAFE LOADINGS ARE DEFINED IN A SPECIFIC WAY AS A FUNCTION OF THE ELASTIC PROPERTIES OF THE MEDIUM. THUS, ELASTIC STIFFNESS TENSOR AND 4TH RANK FAILURE TENSOR AREPROPERLY INTERRELATED.","abstract_html":"THE "ELASTIC STRUCTURE" OF LINEARLY ELASTIC ANISOTROPIC MEDIA WAS STUDIED IN TERMS OF SPECTRAL ANALYSIS THEORY OF 4TH RANK SYMMETRIC TENSORS. BY MEANS OF THE SPECTRAL DECOMPOSITION OF THE TRANSVERSELY ISOTROPIC COMPLIANCE TENSOR, ITS EIGENVALUES AND EIGENTENSORS WERE EXPLICITY DEFINED. IT WAS SHOWN THAT THESE EIGENTENSORS DECOMPOSE THE STRAIN ENERGY DENSITY OF TRANSVERSELY ISOTROPIC MEDIA IN WELL DEFINED PARTS ASSOCIATED WITH EIGENDEFORMATION STATES OF THE MEDIUM, AND AN INTERESTING GEOMETRIC INTERPRETATION WAS GIVEN FOR THESE ELASTIC EIGENSTATES.BY GENERALIZING THE CHARACTERIZATION OF ELASTIC SYMMETRY, THE INFLUENCE OF ORTHOTROPIC COMPLIANCE TENSOR COMPONENTS ON THE INCLUDED STRESS FIELD OF PLANE STRESS PROBLEMS WAS STUDIED. BY CALCULATING THE STRESS FIELD IN THE VICINITY OF ANELLIPTIC CUT OF AN ORTHOTROPIC PLATE, AS WELL AS THE STRESS CONCENTRATION INDUCED ON ITS BOUNDARY, IT WAS PROVED THAT FOR A SPECIFIC COUPLING OF THE COMPLIANCE TENSOR COMPONENTS, THE STRESS CONCENTRATION FACTOR TAKES MINIMUM VALUES. THUS, IT IS PROVED THAT IT IS POSSIBLE TO QUANTITATIVELY CORRELATE FRACTURE TOUGHNESS CHARACTERIZATION OF AN ANISOTROPIC LINEAR ELASTIC MEDIUM WITH THE VALUE OF ITS COMPLIANCE TENSOR COMPONENTS. IN THE SEQUEL, THE ISOTROPIC CRITERION OF THEPARABOLOIDAL FAILURE SURFACE OF REVOLUTION WAS GENERALIZED IN ORDER TO PREDICTFAILURE OF ANISOTROPIC MEDIA, AND EXTREMUM PROPERTIES OF THE FAILURE FUNCTION WERE STUDIED IN A GENERALIZED TENSOR INVARIANT FORM. VARIOUS FEATURES OF THE FAILURE CRITERION WERE STUDIED IN DETAIL AND COMPARISON OF ITS THEORETICAL PREDICTIONS WITH EXPERIMENTAL DATA, ESPECIALLY FROM FAILURE TESTS OF FIBER COMPOSITES, PROVED ITS CORRECTNESS. FINALLY, THE GENERALIZATION OF THE ELLIPTIC PARABOLOID FAILURE CRITERION FOR THE GENERALLY ANISOTROPIC ELASTIC SOLID WAS ATTEMPTED FOR THE CASE THAT HYDROSTATIC COMPRESSION IS NOT A SAFE LOADING ANYMORE, BUT SAFE LOADINGS ARE DEFINED IN A SPECIFIC WAY AS A FUNCTION OF THE ELASTIC PROPERTIES OF THE MEDIUM. THUS, ELASTIC STIFFNESS TENSOR AND 4TH RANK FAILURE TENSOR AREPROPERLY INTERRELATED.","abstract_has_math":false,"creators":["Φιλιππίδης, Θεόδωρος"],"institution":"National Technical University of Athens (NTUA)","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1989,"date_issued":"1989","date_published":"1989","updated_at":"2026-07-24T02:24:46Z","subjects":["Anisotropic elasticiry","Failure criterion","Failure surface","FIBER COMPOSITE MATERIAL","ORTHOTROPIC MEDIUM","TRANSVERSELY ISOTROPIC MEDIUM","ΑΝΙΣΟΤΡΟΠΟΣ ΕΛΑΣΤΙΚΟΤΗΣ","ΕΓΚΑΡΣΙΩΣ ΙΣΟΤΡΟΠΟ ΜΕΣΟΝ","Επιφάνεια αστοχίας","Ινώδες σύνθετο υλικό","ΚΡΙΤΗΡΙΟΝ ΑΣΤΟΧΙΑΣ","ΟΡΘΟΤΡΟΠΟ ΜΕΣΟΝ","Επιστήμες Μηχανικού και Τεχνολογία","Μηχανική Υλικών","Engineering and Technology","Materials Engineering"],"languages":["gre"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["10.12681/eadd/1193"],"render_values":[{"text":"10.12681/eadd/1193","href":"https://doi.org/10.12681/eadd/1193","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10442/hedi/1193","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Φιλιππίδης, Θεόδωρος"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1989"]},{"key":"dc:publisher","label":"Institution","values":["National Technical University of Athens (NTUA)","Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ)"]},{"key":"dc:type","label":"Dc Type","values":["PhD Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Anisotropic elasticiry","Failure criterion","Failure surface","FIBER COMPOSITE MATERIAL","ORTHOTROPIC MEDIUM","TRANSVERSELY ISOTROPIC MEDIUM","ΑΝΙΣΟΤΡΟΠΟΣ ΕΛΑΣΤΙΚΟΤΗΣ","ΕΓΚΑΡΣΙΩΣ ΙΣΟΤΡΟΠΟ ΜΕΣΟΝ","Επιφάνεια αστοχίας","Ινώδες σύνθετο υλικό","ΚΡΙΤΗΡΙΟΝ ΑΣΤΟΧΙΑΣ","ΟΡΘΟΤΡΟΠΟ ΜΕΣΟΝ","Επιστήμες Μηχανικού και Τεχνολογία","Μηχανική Υλικών","Engineering and Technology","Materials Engineering"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["gre"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["10.12681/eadd/1193","http://hdl.handle.net/10442/hedi/1193"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["THE \"ELASTIC STRUCTURE\" OF LINEARLY ELASTIC ANISOTROPIC MEDIA WAS STUDIED IN TERMS OF SPECTRAL ANALYSIS THEORY OF 4TH RANK SYMMETRIC TENSORS. BY MEANS OF THE SPECTRAL DECOMPOSITION OF THE TRANSVERSELY ISOTROPIC COMPLIANCE TENSOR, ITS EIGENVALUES AND EIGENTENSORS WERE EXPLICITY DEFINED. IT WAS SHOWN THAT THESE EIGENTENSORS DECOMPOSE THE STRAIN ENERGY DENSITY OF TRANSVERSELY ISOTROPIC MEDIA IN WELL DEFINED PARTS ASSOCIATED WITH EIGENDEFORMATION STATES OF THE MEDIUM, AND AN INTERESTING GEOMETRIC INTERPRETATION WAS GIVEN FOR THESE ELASTIC EIGENSTATES.BY GENERALIZING THE CHARACTERIZATION OF ELASTIC SYMMETRY, THE INFLUENCE OF ORTHOTROPIC COMPLIANCE TENSOR COMPONENTS ON THE INCLUDED STRESS FIELD OF PLANE STRESS PROBLEMS WAS STUDIED. BY CALCULATING THE STRESS FIELD IN THE VICINITY OF ANELLIPTIC CUT OF AN ORTHOTROPIC PLATE, AS WELL AS THE STRESS CONCENTRATION INDUCED ON ITS BOUNDARY, IT WAS PROVED THAT FOR A SPECIFIC COUPLING OF THE COMPLIANCE TENSOR COMPONENTS, THE STRESS CONCENTRATION FACTOR TAKES MINIMUM VALUES. THUS, IT IS PROVED THAT IT IS POSSIBLE TO QUANTITATIVELY CORRELATE FRACTURE TOUGHNESS CHARACTERIZATION OF AN ANISOTROPIC LINEAR ELASTIC MEDIUM WITH THE VALUE OF ITS COMPLIANCE TENSOR COMPONENTS. IN THE SEQUEL, THE ISOTROPIC CRITERION OF THEPARABOLOIDAL FAILURE SURFACE OF REVOLUTION WAS GENERALIZED IN ORDER TO PREDICTFAILURE OF ANISOTROPIC MEDIA, AND EXTREMUM PROPERTIES OF THE FAILURE FUNCTION WERE STUDIED IN A GENERALIZED TENSOR INVARIANT FORM. VARIOUS FEATURES OF THE FAILURE CRITERION WERE STUDIED IN DETAIL AND COMPARISON OF ITS THEORETICAL PREDICTIONS WITH EXPERIMENTAL DATA, ESPECIALLY FROM FAILURE TESTS OF FIBER COMPOSITES, PROVED ITS CORRECTNESS. FINALLY, THE GENERALIZATION OF THE ELLIPTIC PARABOLOID FAILURE CRITERION FOR THE GENERALLY ANISOTROPIC ELASTIC SOLID WAS ATTEMPTED FOR THE CASE THAT HYDROSTATIC COMPRESSION IS NOT A SAFE LOADING ANYMORE, BUT SAFE LOADINGS ARE DEFINED IN A SPECIFIC WAY AS A FUNCTION OF THE ELASTIC PROPERTIES OF THE MEDIUM. THUS, ELASTIC STIFFNESS TENSOR AND 4TH RANK FAILURE TENSOR AREPROPERLY INTERRELATED.","ΜΕΛΕΤΑΤΑΙ Η \"ΕΛΑΣΤΙΚΗ ΔΟΜΗ\" ΑΝΙΣΟΤΡΟΠΩΝ ΓΡΑΜΜΙΚΩΣ ΕΛΑΣΤΙΚΩΝ ΜΕΣΩΝ ΔΙΑ ΤΗΣ ΘΕΩΡΙΑΣ ΤΗΣ ΦΑΣΜΑΤΙΚΗΣ ΑΝΑΛΥΣΕΩΣ ΤΩΝ ΣΥΜΜΕΤΡΙΚΩΝ ΤΑΝΥΣΤΩΝ 4ΗΣ ΤΑΞΕΩΣ. ΔΙΑ ΤΗΣ ΦΑΣΜΑΤΙΚΗΣ ΑΝΑΠΤΥΞΕΩΣ ΤΩΝ ΕΓΚΑΡΣΙΩΣ ΙΣΟΤΡΟΠΩΝ ΜΕΣΩΝ ΠΡΟΣΔΙΟΡΙΖΟΝΤΑΙ ΑΝΑΛΥΤΙΚΩΣ ΟΙ ΙΔΙΟΤΙΜΕΣ ΚΑΙ ΟΙ ΙΔΙΟΤΑΝΥΣΤΕΣ ΤΟΥ 4ΗΣ ΤΑΞΕΩΣ ΤΑΝΥΣΤΟΥ ΕΚΔΟΣΕΩΣ. ΑΠΟΔΕΙΚΝΥΕΤΑΙ ΟΤΙ ΟΙ ΙΔΙΟΤΑΝΥΣΤΕΣ ΑΥΤΟΙ ΑΝΑΛΥΟΥΝ ΤΗΝ ΠΥΚΝΟΤΗΤΑ ΕΝΕΡΓΕΙΑΣ ΠΑΡΑΜΟΡΦΩΣΕΩΝ ΤΩΝ ΕΓΚ. ΙΣΟΤΡ. ΜΕΣΩΝ ΣΕ ΤΜΗΜΑΤΑ ΣΑΦΩΣ ΚΑΘΟΡΙΣΜΕΝΑ ΑΝΤΙΣΤΟΙΧΟΥΝΤΑ ΣΤΙΣ ΙΔΙΟΠΑΡΑΜΟΡΦΩΣΕΙΣ ΤΗΣ ΕΝ ΛΟΓΩ ΕΛΑΣΤΙΚΗΣ ΣΥΜΜΕΤΡΙΑΣ ΚΑΙ ΔΙΔΕΤΑΙ ΕΝΔΙΑΦΕΡΟΥΣΑ ΓΕΩΜΕΤΡΙΚΗ ΕΡΜΗΝΕΙΑ ΤΩΝ ΕΛΑΣΤΙΚΩΝ ΙΔΙΟΚΑΤΑΣΤΑΣΕΩΝ ΑΥΤΩΝ. ΓΕΝΙΚΕΥΟΝΤΑΣ ΤΟΝ ΧΑΡΑΚΤΗΡΙΣΜΟ ΤΗΣ ΕΛΑΣΤΙΚΗΣΣΥΜΜΕΤΡΙΑΣ, ΜΕΛΕΤΩΝΤΑΙ ΚΑΤΑ ΒΑΣΙΝ ΟΡΘΟΤΡΟΠΑ ΓΡΑΜΜΙΚΑ ΕΛΑΣΤΙΚΑ ΥΛΙΚΑ ΚΑΙ ΕΙΔΙΚΩΣ Η ΕΠΙΡΡΟΗ ΤΩΝ ΤΙΜΩΝ ΤΩΝ ΣΥΝΙΣΤΩΣΩΝ ΤΟΥ ΤΑΝΥΣΤΟΥ ΕΚΔΟΣΕΩΣ ΕΠΙ ΤΟΥ ΑΝΑΠΤΥΣΣΟΜΕΝΟΥ ΠΕΔΙΟΥ ΤΑΣΕΩΝ ΣΕ ΠΡΟΒΛΗΜΑΤΑ ΕΠΙΠΕΔΟΥ ΑΝΙΣΟΤΡΟΠΟΥ ΕΛΑΣΤΙΚΟΤΗΤΟΣ. ΥΠΟΛΟΓΙΖΟΝΤΑΣ ΤΟ ΤΑΣΙΚΟ ΠΕΔΙΟ ΣΤΗΝ ΓΕΙΤΟΝΙΑ ΕΛΛΕΙΠΤΙΚΗΣ ΡΩΓΜΗΣ ΣΕ ΟΡΘΟΤΡΟΠΗ ΠΛΑΚΑ ΚΑΙ ΕΞΕΤΑΖΟΝΤΑΣ ΤΟΝ ΣΥΝΤΕΛΕΣΤΗ ΣΥΓΚΕΝΤΡΩΣΕΩΣ ΤΑΣΕΩΝ ΑΠΟΔΕΙΚΝΥΕΤΑΙ ΟΤΙ ΓΙΑ ΚΑΘΟΡΙΣΜΕΝΗ ΣΥΖΕΥΞΗ ΤΩΝ ΣΥΝΙΣΤΩΣΩΝ ΤΟΥ ΤΑΝΥΣΤΟΥ ΕΚΔΟΣΕΩΣ, Ο ΣΥΝΤΕΛΕΣΤΗΣ ΣΥΓΚΕΝΤΡΩΣΕΩΣ ΛΑΜΒΑΝΕΙ ΕΛΑΧΙΣΤΕΣ ΤΙΜΕΣ . ΑΠΟΔΕΙΚΝΥΕΤΑΙ ΕΤΣΙ ΟΤΙ ΕΙΝΑΙ ΔΥΝΑΤΟΝ ΝΑ ΣΥΣΧΕΤΙΣΘΕΙ ΠΟΙΟΤΙΚΩΣ Η ΣΤΕΡΡΟΤΗΣ ΘΡΑΥΣΕΩΣ ΑΝΙΣΟΤΡΟΠΟΥ ΓΡΑΜΜΙΚΩΣ ΕΛΑΣΤΙΚΟΥ ΜΕΣΟΥ ΜΕ ΤΙΣ ΤΙΜΕΣ ΤΩΝΣΥΝΙΣΤΩΣΩΝ ΤΟΥ ΤΑΝΥΣΤΟΥ ΕΚΔΟΣΕΩΣ . ΣΤΗΝ ΣΥΝΕΧΕΙΑ ΓΕΝΙΚΕΥΕΤΑΙ ΤΟ ΚΡΙΤΗΡΙΟ ΤΗΣ ΕΚ ΠΕΡΙΣΤΡΟΦΗΣ ΠΑΡΑΒΟΛΟΕΙΔΟΥΣ ΕΠΙΦΑΝΕΙΑΣ ΑΣΤΟΧΙΑΣ ΚΑΤΑΛΛΗΛΟ ΓΙΑ ΙΣΟΤΡΟΠΑ ΥΛΙΚΑ, ΓΙΑ ΤΟ ΓΕΝΙΚΩΣ ΑΝΙΣΟΤΡΟΠΟ ΕΛΑΣΤΙΚΟ ΜΕΣΟΝ ΚΑΙ ΜΕΛΕΤΩΝΤΑΙ ΟΙ ΙΔΙΟΤΗΤΕΣ ΑΚΡΟΤΑΤΩΝ ΤΗΣ ΣΥΝΑΡΤΗΣΕΩΣ ΑΣΤΟΧΙΑΣ ΥΠΟ ΓΕΝΙΚΕΥΜΕΝΗ ΤΑΝΥΣΤΙΚΗ ΑΝΑΛΛΟΙΩΤΟ ΜΟΡΦΗ. ΤΟ ΚΡΙΤΗΡΙΟ ΑΣΤΟΧΙΑΣ ΜΕΛΕΤΑΤΑΙ ΛΕΠΤΟΜΕΡΩΣ ΚΑΙ ΕΥΡΙΣΚΕΤΑΙ ΝΑ ΔΙΔΗ ΙΚΑΝΟΠΟΙΗΤΙΚΕΣ ΘΕΩΡΗΤΙΚΕΣ ΠΡΟΒΛΕΨΕΙΣ ΣΥΓΚΡΙΝΟΜΕΝΕΣ ΔΙΑ ΠΕΙΡΑΜΑΤΙΚΩΝ ΑΠΟΤΕΛΕΣΜΑΤΩΝ ΕΚ ΔΟΚΙΜΩΝ ΑΣΤΟΧΙΑΣ, ΚΥΡΙΩΣ ΙΝΩΔΩΝ ΣΥΝΘΕΤΩΝ ΥΛΙΚΩΝ. ΤΕΛΟΣ, ΜΕΛΕΤΑΤΑΙ Η ΓΕΝΙΚΕΥΣΗΣ ΤΟΥ ΚΡΙΤΗΡΙΟΥ ΑΣΤΟΧΙΑΣ ΤΗΣ ΠΑΡΑΒΟΛΟΕΙΔΟΥΣ ΕΠΙΦΑΝΕΙΑΣ ΓΙΑ ΤΟ ΓΕΝΙΚΩΣ ΑΝΙΣΟΤΡΟΠΟ ΕΛΑΣΤΙΚΟ ΜΕΣΟ ΓΙΑ ΤΗΝ ΠΕΡΙΠΤΩΣΗ ΠΟΥ Η ΑΣΦΑΛΗΣ ΦΟΡΤΙΣΗ ΔΙΑΦΕΡΕΙ ΤΗΣ ΥΔΡΟΣΤΑΤΙΚΗΣ ΘΛΙΨΕΩΣ, ΑΛΛΑ ΠΡΟΣΔΙΟΡΙΖΕΤΑΙ ΜΕ ΣΥΓΚΕΚΡΙΜΕΝΟ ΤΡΟΠΟ ΣΥΝΑΡΤΗΣΕΙ ΤΩΝ ΕΛΑΣΤΙΚΩΝ ΙΔΙΟΤΗΤΩΝ ΤΟΥ ΜΕΣΟΥ.ΤΟΙΟΥΤΟΤΡΟΠΩΣ, ΕΠΙΤΥΓΧΑΝΕΤΑΙ ΔΙΑΣΥΝΔΕΣΗΣ ΤΟΥ ΕΛΑΣΤΙΚΟΥ ΤΑΝΥΣΤΟΥ ΔΥΣΚΑΜΨΙΑΣ ΜΕ ΤΟΝ ΤΑΝΥΣΤΗ ΑΣΤΟΧΙΑΣ 4ΗΣ ΤΑΞΕΩΣ ΤΗΣ ΟΡΙΑΚΗΣ ΣΥΝΑΡΤΗΣΕΩΣ."]},{"key":"dc:title","label":"Title","values":["ΓΕΝΙΚΕΥΜΕΝΑ ΚΡΙΤΗΡΙΑ ΑΣΤΟΧΙΑΣ ΑΡΧΙΚΩΣ ΑΝΙΣΟΤΡΟΠΩΝ ΕΛΑΣΤΙΚΩΝ ΜΕΣΩΝ ΜΕ ΙΔΙΑΙΤΕΡΗ ΕΜΦΑΣΗ ΣΤΑ ΣΥΝΘΕΤΑ ΥΛΙΚΑ","GENERALIZED FAILURE CRITERIA OF INITIALLY ANISOTROPIC ELASTIC MEDIA WITH SPECIAL EMPHASIS ON COMPOSITE MATERIALS"]}]}],"canonical_facts":{"dc:creator":["Φιλιππίδης, Θεόδωρος"],"dc:date":["1989"],"dc:description":["THE \"ELASTIC STRUCTURE\" OF LINEARLY ELASTIC ANISOTROPIC MEDIA WAS STUDIED IN TERMS OF SPECTRAL ANALYSIS THEORY OF 4TH RANK SYMMETRIC TENSORS. BY MEANS OF THE SPECTRAL DECOMPOSITION OF THE TRANSVERSELY ISOTROPIC COMPLIANCE TENSOR, ITS EIGENVALUES AND EIGENTENSORS WERE EXPLICITY DEFINED. IT WAS SHOWN THAT THESE EIGENTENSORS DECOMPOSE THE STRAIN ENERGY DENSITY OF TRANSVERSELY ISOTROPIC MEDIA IN WELL DEFINED PARTS ASSOCIATED WITH EIGENDEFORMATION STATES OF THE MEDIUM, AND AN INTERESTING GEOMETRIC INTERPRETATION WAS GIVEN FOR THESE ELASTIC EIGENSTATES.BY GENERALIZING THE CHARACTERIZATION OF ELASTIC SYMMETRY, THE INFLUENCE OF ORTHOTROPIC COMPLIANCE TENSOR COMPONENTS ON THE INCLUDED STRESS FIELD OF PLANE STRESS PROBLEMS WAS STUDIED. BY CALCULATING THE STRESS FIELD IN THE VICINITY OF ANELLIPTIC CUT OF AN ORTHOTROPIC PLATE, AS WELL AS THE STRESS CONCENTRATION INDUCED ON ITS BOUNDARY, IT WAS PROVED THAT FOR A SPECIFIC COUPLING OF THE COMPLIANCE TENSOR COMPONENTS, THE STRESS CONCENTRATION FACTOR TAKES MINIMUM VALUES. THUS, IT IS PROVED THAT IT IS POSSIBLE TO QUANTITATIVELY CORRELATE FRACTURE TOUGHNESS CHARACTERIZATION OF AN ANISOTROPIC LINEAR ELASTIC MEDIUM WITH THE VALUE OF ITS COMPLIANCE TENSOR COMPONENTS. IN THE SEQUEL, THE ISOTROPIC CRITERION OF THEPARABOLOIDAL FAILURE SURFACE OF REVOLUTION WAS GENERALIZED IN ORDER TO PREDICTFAILURE OF ANISOTROPIC MEDIA, AND EXTREMUM PROPERTIES OF THE FAILURE FUNCTION WERE STUDIED IN A GENERALIZED TENSOR INVARIANT FORM. VARIOUS FEATURES OF THE FAILURE CRITERION WERE STUDIED IN DETAIL AND COMPARISON OF ITS THEORETICAL PREDICTIONS WITH EXPERIMENTAL DATA, ESPECIALLY FROM FAILURE TESTS OF FIBER COMPOSITES, PROVED ITS CORRECTNESS. FINALLY, THE GENERALIZATION OF THE ELLIPTIC PARABOLOID FAILURE CRITERION FOR THE GENERALLY ANISOTROPIC ELASTIC SOLID WAS ATTEMPTED FOR THE CASE THAT HYDROSTATIC COMPRESSION IS NOT A SAFE LOADING ANYMORE, BUT SAFE LOADINGS ARE DEFINED IN A SPECIFIC WAY AS A FUNCTION OF THE ELASTIC PROPERTIES OF THE MEDIUM. THUS, ELASTIC STIFFNESS TENSOR AND 4TH RANK FAILURE TENSOR AREPROPERLY INTERRELATED.","ΜΕΛΕΤΑΤΑΙ Η \"ΕΛΑΣΤΙΚΗ ΔΟΜΗ\" ΑΝΙΣΟΤΡΟΠΩΝ ΓΡΑΜΜΙΚΩΣ ΕΛΑΣΤΙΚΩΝ ΜΕΣΩΝ ΔΙΑ ΤΗΣ ΘΕΩΡΙΑΣ ΤΗΣ ΦΑΣΜΑΤΙΚΗΣ ΑΝΑΛΥΣΕΩΣ ΤΩΝ ΣΥΜΜΕΤΡΙΚΩΝ ΤΑΝΥΣΤΩΝ 4ΗΣ ΤΑΞΕΩΣ. ΔΙΑ ΤΗΣ ΦΑΣΜΑΤΙΚΗΣ ΑΝΑΠΤΥΞΕΩΣ ΤΩΝ ΕΓΚΑΡΣΙΩΣ ΙΣΟΤΡΟΠΩΝ ΜΕΣΩΝ ΠΡΟΣΔΙΟΡΙΖΟΝΤΑΙ ΑΝΑΛΥΤΙΚΩΣ ΟΙ ΙΔΙΟΤΙΜΕΣ ΚΑΙ ΟΙ ΙΔΙΟΤΑΝΥΣΤΕΣ ΤΟΥ 4ΗΣ ΤΑΞΕΩΣ ΤΑΝΥΣΤΟΥ ΕΚΔΟΣΕΩΣ. ΑΠΟΔΕΙΚΝΥΕΤΑΙ ΟΤΙ ΟΙ ΙΔΙΟΤΑΝΥΣΤΕΣ ΑΥΤΟΙ ΑΝΑΛΥΟΥΝ ΤΗΝ ΠΥΚΝΟΤΗΤΑ ΕΝΕΡΓΕΙΑΣ ΠΑΡΑΜΟΡΦΩΣΕΩΝ ΤΩΝ ΕΓΚ. ΙΣΟΤΡ. ΜΕΣΩΝ ΣΕ ΤΜΗΜΑΤΑ ΣΑΦΩΣ ΚΑΘΟΡΙΣΜΕΝΑ ΑΝΤΙΣΤΟΙΧΟΥΝΤΑ ΣΤΙΣ ΙΔΙΟΠΑΡΑΜΟΡΦΩΣΕΙΣ ΤΗΣ ΕΝ ΛΟΓΩ ΕΛΑΣΤΙΚΗΣ ΣΥΜΜΕΤΡΙΑΣ ΚΑΙ ΔΙΔΕΤΑΙ ΕΝΔΙΑΦΕΡΟΥΣΑ ΓΕΩΜΕΤΡΙΚΗ ΕΡΜΗΝΕΙΑ ΤΩΝ ΕΛΑΣΤΙΚΩΝ ΙΔΙΟΚΑΤΑΣΤΑΣΕΩΝ ΑΥΤΩΝ. ΓΕΝΙΚΕΥΟΝΤΑΣ ΤΟΝ ΧΑΡΑΚΤΗΡΙΣΜΟ ΤΗΣ ΕΛΑΣΤΙΚΗΣΣΥΜΜΕΤΡΙΑΣ, ΜΕΛΕΤΩΝΤΑΙ ΚΑΤΑ ΒΑΣΙΝ ΟΡΘΟΤΡΟΠΑ ΓΡΑΜΜΙΚΑ ΕΛΑΣΤΙΚΑ ΥΛΙΚΑ ΚΑΙ ΕΙΔΙΚΩΣ Η ΕΠΙΡΡΟΗ ΤΩΝ ΤΙΜΩΝ ΤΩΝ ΣΥΝΙΣΤΩΣΩΝ ΤΟΥ ΤΑΝΥΣΤΟΥ ΕΚΔΟΣΕΩΣ ΕΠΙ ΤΟΥ ΑΝΑΠΤΥΣΣΟΜΕΝΟΥ ΠΕΔΙΟΥ ΤΑΣΕΩΝ ΣΕ ΠΡΟΒΛΗΜΑΤΑ ΕΠΙΠΕΔΟΥ ΑΝΙΣΟΤΡΟΠΟΥ ΕΛΑΣΤΙΚΟΤΗΤΟΣ. ΥΠΟΛΟΓΙΖΟΝΤΑΣ ΤΟ ΤΑΣΙΚΟ ΠΕΔΙΟ ΣΤΗΝ ΓΕΙΤΟΝΙΑ ΕΛΛΕΙΠΤΙΚΗΣ ΡΩΓΜΗΣ ΣΕ ΟΡΘΟΤΡΟΠΗ ΠΛΑΚΑ ΚΑΙ ΕΞΕΤΑΖΟΝΤΑΣ ΤΟΝ ΣΥΝΤΕΛΕΣΤΗ ΣΥΓΚΕΝΤΡΩΣΕΩΣ ΤΑΣΕΩΝ ΑΠΟΔΕΙΚΝΥΕΤΑΙ ΟΤΙ ΓΙΑ ΚΑΘΟΡΙΣΜΕΝΗ ΣΥΖΕΥΞΗ ΤΩΝ ΣΥΝΙΣΤΩΣΩΝ ΤΟΥ ΤΑΝΥΣΤΟΥ ΕΚΔΟΣΕΩΣ, Ο ΣΥΝΤΕΛΕΣΤΗΣ ΣΥΓΚΕΝΤΡΩΣΕΩΣ ΛΑΜΒΑΝΕΙ ΕΛΑΧΙΣΤΕΣ ΤΙΜΕΣ . ΑΠΟΔΕΙΚΝΥΕΤΑΙ ΕΤΣΙ ΟΤΙ ΕΙΝΑΙ ΔΥΝΑΤΟΝ ΝΑ ΣΥΣΧΕΤΙΣΘΕΙ ΠΟΙΟΤΙΚΩΣ Η ΣΤΕΡΡΟΤΗΣ ΘΡΑΥΣΕΩΣ ΑΝΙΣΟΤΡΟΠΟΥ ΓΡΑΜΜΙΚΩΣ ΕΛΑΣΤΙΚΟΥ ΜΕΣΟΥ ΜΕ ΤΙΣ ΤΙΜΕΣ ΤΩΝΣΥΝΙΣΤΩΣΩΝ ΤΟΥ ΤΑΝΥΣΤΟΥ ΕΚΔΟΣΕΩΣ . ΣΤΗΝ ΣΥΝΕΧΕΙΑ ΓΕΝΙΚΕΥΕΤΑΙ ΤΟ ΚΡΙΤΗΡΙΟ ΤΗΣ ΕΚ ΠΕΡΙΣΤΡΟΦΗΣ ΠΑΡΑΒΟΛΟΕΙΔΟΥΣ ΕΠΙΦΑΝΕΙΑΣ ΑΣΤΟΧΙΑΣ ΚΑΤΑΛΛΗΛΟ ΓΙΑ ΙΣΟΤΡΟΠΑ ΥΛΙΚΑ, ΓΙΑ ΤΟ ΓΕΝΙΚΩΣ ΑΝΙΣΟΤΡΟΠΟ ΕΛΑΣΤΙΚΟ ΜΕΣΟΝ ΚΑΙ ΜΕΛΕΤΩΝΤΑΙ ΟΙ ΙΔΙΟΤΗΤΕΣ ΑΚΡΟΤΑΤΩΝ ΤΗΣ ΣΥΝΑΡΤΗΣΕΩΣ ΑΣΤΟΧΙΑΣ ΥΠΟ ΓΕΝΙΚΕΥΜΕΝΗ ΤΑΝΥΣΤΙΚΗ ΑΝΑΛΛΟΙΩΤΟ ΜΟΡΦΗ. ΤΟ ΚΡΙΤΗΡΙΟ ΑΣΤΟΧΙΑΣ ΜΕΛΕΤΑΤΑΙ ΛΕΠΤΟΜΕΡΩΣ ΚΑΙ ΕΥΡΙΣΚΕΤΑΙ ΝΑ ΔΙΔΗ ΙΚΑΝΟΠΟΙΗΤΙΚΕΣ ΘΕΩΡΗΤΙΚΕΣ ΠΡΟΒΛΕΨΕΙΣ ΣΥΓΚΡΙΝΟΜΕΝΕΣ ΔΙΑ ΠΕΙΡΑΜΑΤΙΚΩΝ ΑΠΟΤΕΛΕΣΜΑΤΩΝ ΕΚ ΔΟΚΙΜΩΝ ΑΣΤΟΧΙΑΣ, ΚΥΡΙΩΣ ΙΝΩΔΩΝ ΣΥΝΘΕΤΩΝ ΥΛΙΚΩΝ. ΤΕΛΟΣ, ΜΕΛΕΤΑΤΑΙ Η ΓΕΝΙΚΕΥΣΗΣ ΤΟΥ ΚΡΙΤΗΡΙΟΥ ΑΣΤΟΧΙΑΣ ΤΗΣ ΠΑΡΑΒΟΛΟΕΙΔΟΥΣ ΕΠΙΦΑΝΕΙΑΣ ΓΙΑ ΤΟ ΓΕΝΙΚΩΣ ΑΝΙΣΟΤΡΟΠΟ ΕΛΑΣΤΙΚΟ ΜΕΣΟ ΓΙΑ ΤΗΝ ΠΕΡΙΠΤΩΣΗ ΠΟΥ Η ΑΣΦΑΛΗΣ ΦΟΡΤΙΣΗ ΔΙΑΦΕΡΕΙ ΤΗΣ ΥΔΡΟΣΤΑΤΙΚΗΣ ΘΛΙΨΕΩΣ, ΑΛΛΑ ΠΡΟΣΔΙΟΡΙΖΕΤΑΙ ΜΕ ΣΥΓΚΕΚΡΙΜΕΝΟ ΤΡΟΠΟ ΣΥΝΑΡΤΗΣΕΙ ΤΩΝ ΕΛΑΣΤΙΚΩΝ ΙΔΙΟΤΗΤΩΝ ΤΟΥ ΜΕΣΟΥ.ΤΟΙΟΥΤΟΤΡΟΠΩΣ, ΕΠΙΤΥΓΧΑΝΕΤΑΙ ΔΙΑΣΥΝΔΕΣΗΣ ΤΟΥ ΕΛΑΣΤΙΚΟΥ ΤΑΝΥΣΤΟΥ ΔΥΣΚΑΜΨΙΑΣ ΜΕ ΤΟΝ ΤΑΝΥΣΤΗ ΑΣΤΟΧΙΑΣ 4ΗΣ ΤΑΞΕΩΣ ΤΗΣ ΟΡΙΑΚΗΣ ΣΥΝΑΡΤΗΣΕΩΣ."],"dc:identifier":["10.12681/eadd/1193","http://hdl.handle.net/10442/hedi/1193"],"dc:language":["gre"],"dc:publisher":["National Technical University of Athens (NTUA)","Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ)"],"dc:subject":["Anisotropic elasticiry","Failure criterion","Failure surface","FIBER COMPOSITE MATERIAL","ORTHOTROPIC MEDIUM","TRANSVERSELY ISOTROPIC MEDIUM","ΑΝΙΣΟΤΡΟΠΟΣ ΕΛΑΣΤΙΚΟΤΗΣ","ΕΓΚΑΡΣΙΩΣ ΙΣΟΤΡΟΠΟ ΜΕΣΟΝ","Επιφάνεια αστοχίας","Ινώδες σύνθετο υλικό","ΚΡΙΤΗΡΙΟΝ ΑΣΤΟΧΙΑΣ","ΟΡΘΟΤΡΟΠΟ ΜΕΣΟΝ","Επιστήμες Μηχανικού και Τεχνολογία","Μηχανική Υλικών","Engineering and Technology","Materials Engineering"],"dc:title":["ΓΕΝΙΚΕΥΜΕΝΑ ΚΡΙΤΗΡΙΑ ΑΣΤΟΧΙΑΣ ΑΡΧΙΚΩΣ ΑΝΙΣΟΤΡΟΠΩΝ ΕΛΑΣΤΙΚΩΝ ΜΕΣΩΝ ΜΕ ΙΔΙΑΙΤΕΡΗ ΕΜΦΑΣΗ ΣΤΑ ΣΥΝΘΕΤΑ ΥΛΙΚΑ","GENERALIZED FAILURE CRITERIA OF INITIALLY ANISOTROPIC ELASTIC MEDIA WITH SPECIAL EMPHASIS ON COMPOSITE MATERIALS"],"dc:type":["PhD Thesis"]},"updated_at":"2026-07-24T02:24:46Z"}