{"id":{"repo_id":"greece","oai_identifier":"oai:10442/1138"},"canonical_url":"https://search.dev.ndltd.org/etd/greece/oai:10442/1138","repository":{"repo_id":"greece","name":"Greek National Archive of PhD Theses","base_url":"https://phdtheses.ekt.gr/eadd_oai/request"},"display":{"title":"ΦΑΙΝΟΜΕΝΑ ΑΣΤΑΘΕΙΑΣ ΤΗΣ ΔΙΕΥΘΥΝΣΕΩΣ ΤΑΧΕΩΣ ΚΙΝΟΥΜΕΝΩΝ ΡΩΓΜΩΝ","abstract":"IN THE PRESENT DISSERTATION THE PHENOMENA OF DYNAMIC CRACK INSTABILITY ARE STUDIED FOR FAST RUNNING CRACKS. THESE PHENOMENA ARE: DYNAMIC BRANCHING, DYNAMIC CURVING, DYNAMIC KINKING AND CRACK ARREST. A SERIES OF EXPERIMENTS PROVES THAT THE EXISTING \"YOTTE MODE\" FOR APPLYING MACROSCOPIC FRACTURE CRITERIA FAILS TO GIVE CORRECT RESULTS IN THE CASE OF MOVING CRACKS. A NEW MODE FOR APPLYING THESE CRITERIA IS PROPOSED AND DESCRIBED IN THE SEQUEL. THIS MODE IS BASED ON THE INTRODUCTION OF TWO NEW QUANTITIES IN THE MICROSCOPIC LEVEL, AND ON THE HYPOTHESIS THAT THE CRACK FOR THE EARLYN STEPS OF ITS PROPAGATION IS MOVING IN THE FORM OFA TWIN SINGULARITY. THE RESULTS OF THE APPLICATION WITH EXPERIMENTAL EVIDENCE.IN THE SEQUEL THE SOURCES OF THE ABOVE MENTIONED PHENOMENA ARE INVESTIGATED ASRESULTS OF THE LOCAL ANISOTROPIES AROUND THE MOVING CRACK-TIP CAUSED BY THE MOVEMENT OF THE CRACK.","abstract_html":"IN THE PRESENT DISSERTATION THE PHENOMENA OF DYNAMIC CRACK INSTABILITY ARE STUDIED FOR FAST RUNNING CRACKS. THESE PHENOMENA ARE: DYNAMIC BRANCHING, DYNAMIC CURVING, DYNAMIC KINKING AND CRACK ARREST. A SERIES OF EXPERIMENTS PROVES THAT THE EXISTING "YOTTE MODE" FOR APPLYING MACROSCOPIC FRACTURE CRITERIA FAILS TO GIVE CORRECT RESULTS IN THE CASE OF MOVING CRACKS. A NEW MODE FOR APPLYING THESE CRITERIA IS PROPOSED AND DESCRIBED IN THE SEQUEL. THIS MODE IS BASED ON THE INTRODUCTION OF TWO NEW QUANTITIES IN THE MICROSCOPIC LEVEL, AND ON THE HYPOTHESIS THAT THE CRACK FOR THE EARLYN STEPS OF ITS PROPAGATION IS MOVING IN THE FORM OFA TWIN SINGULARITY. THE RESULTS OF THE APPLICATION WITH EXPERIMENTAL EVIDENCE.IN THE SEQUEL THE SOURCES OF THE ABOVE MENTIONED PHENOMENA ARE INVESTIGATED ASRESULTS OF THE LOCAL ANISOTROPIES AROUND THE MOVING CRACK-TIP CAUSED BY THE MOVEMENT OF THE CRACK.","abstract_has_math":false,"creators":["Κουρκούλης, Σταύρος","Kourkoulis, Stavros"],"institution":"Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ)","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":["(DYNAMIC) CRACK BRANCHING","(DYNAMIC) CRACK CURVING","(DYNAMIC) CRACK PATH INSTABILITY","(DYNAMIC) CRACKKINKING","(ΔΥΝΑΜΙΚΗ) ΔΙΧΑΛΩΣΗ ΡΩΓΜΩΝ","(ΔΥΝΑΜΙΚΗ) ΛΟΞΩΣΗ ΡΩΓΜΩΝ","CRACK ARREST","CRACK PROPAGATION CRITERIA","DYNAMIC MODULES OF ELASTICITY","DYNAMIC STRESS FIELD","DYNAMIC STRESS INTENSITY FACTOR","ΑΚΙΝΗΤΟΠΟΙΗΣΗ ΡΩΓΜΩΝ","ΑΣΤΑΘΕΙΑ ΤΗΣ ΔΙΕΥΘΥΝΣΕΩΣ ΤΩΝ ΡΩΓΜΩΝ","ΔΥΝΑΜΙΚΟ ΜΕΤΡΟ ΕΛΑΣΤΙΚΟΤΗΤΑΣ","ΔΥΝΑΜΙΚΟ ΤΑΣΙΚΟ ΠΕΔΙΟ","ΔΥΝΑΜΙΚΟΣ ΣΥΝΤΕΛΕΣΤΗΣ ΕΝΤΑΣΕΩΣ ΤΩΝ ΤΑΣΕΩΝ","ΚΡΙΤΗΡΙΑ ΔΙΑΔΟΣΕΩΣ ΡΩΓΜΩΝ","Engineering and Technology","Mechanical Engineering","Επιστήμες Μηχανικού και Τεχνολογία","Επιστήμη Μηχανολόγου Μηχανικού"],"languages":["gre"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["10.12681/eadd/1138"],"render_values":[{"text":"10.12681/eadd/1138","href":"https://doi.org/10.12681/eadd/1138","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10442/hedi/1138","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Κουρκούλης, Σταύρος","Kourkoulis, Stavros"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1989"]},{"key":"dc:publisher","label":"Institution","values":["Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ)","National Technical University of Athens (NTUA)"]},{"key":"dc:type","label":"Dc Type","values":["PhD Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["(DYNAMIC) CRACK BRANCHING","(DYNAMIC) CRACK CURVING","(DYNAMIC) CRACK PATH INSTABILITY","(DYNAMIC) CRACKKINKING","(ΔΥΝΑΜΙΚΗ) ΔΙΧΑΛΩΣΗ ΡΩΓΜΩΝ","(ΔΥΝΑΜΙΚΗ) ΛΟΞΩΣΗ ΡΩΓΜΩΝ","CRACK ARREST","CRACK PROPAGATION CRITERIA","DYNAMIC MODULES OF ELASTICITY","DYNAMIC STRESS FIELD","DYNAMIC STRESS INTENSITY FACTOR","ΑΚΙΝΗΤΟΠΟΙΗΣΗ ΡΩΓΜΩΝ","ΑΣΤΑΘΕΙΑ ΤΗΣ ΔΙΕΥΘΥΝΣΕΩΣ ΤΩΝ ΡΩΓΜΩΝ","ΔΥΝΑΜΙΚΟ ΜΕΤΡΟ ΕΛΑΣΤΙΚΟΤΗΤΑΣ","ΔΥΝΑΜΙΚΟ ΤΑΣΙΚΟ ΠΕΔΙΟ","ΔΥΝΑΜΙΚΟΣ ΣΥΝΤΕΛΕΣΤΗΣ ΕΝΤΑΣΕΩΣ ΤΩΝ ΤΑΣΕΩΝ","ΚΡΙΤΗΡΙΑ ΔΙΑΔΟΣΕΩΣ ΡΩΓΜΩΝ","Engineering and Technology","Mechanical Engineering","Επιστήμες Μηχανικού και Τεχνολογία","Επιστήμη Μηχανολόγου Μηχανικού"]}]},{"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/1138","http://hdl.handle.net/10442/hedi/1138"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["IN THE PRESENT DISSERTATION THE PHENOMENA OF DYNAMIC CRACK INSTABILITY ARE STUDIED FOR FAST RUNNING CRACKS. THESE PHENOMENA ARE: DYNAMIC BRANCHING, DYNAMIC CURVING, DYNAMIC KINKING AND CRACK ARREST. A SERIES OF EXPERIMENTS PROVES THAT THE EXISTING \"YOTTE MODE\" FOR APPLYING MACROSCOPIC FRACTURE CRITERIA FAILS TO GIVE CORRECT RESULTS IN THE CASE OF MOVING CRACKS. A NEW MODE FOR APPLYING THESE CRITERIA IS PROPOSED AND DESCRIBED IN THE SEQUEL. THIS MODE IS BASED ON THE INTRODUCTION OF TWO NEW QUANTITIES IN THE MICROSCOPIC LEVEL, AND ON THE HYPOTHESIS THAT THE CRACK FOR THE EARLYN STEPS OF ITS PROPAGATION IS MOVING IN THE FORM OFA TWIN SINGULARITY. THE RESULTS OF THE APPLICATION WITH EXPERIMENTAL EVIDENCE.IN THE SEQUEL THE SOURCES OF THE ABOVE MENTIONED PHENOMENA ARE INVESTIGATED ASRESULTS OF THE LOCAL ANISOTROPIES AROUND THE MOVING CRACK-TIP CAUSED BY THE MOVEMENT OF THE CRACK.","ΣΤΗΝ ΠΑΡΟΥΣΑ ΔΙΑΤΡΙΒΗ ΜΕΛΕΤΩΝΤΑΙ ΤΑ ΦΑΙΝΟΜΕΝΑ ΑΣΤΑΘΕΙΑΣ ΤΗΣ ΔΙΕΥΘΥΝΣΕΩΣ ΤΑΧΕΩΣ ΚΙΝΟΥΜΕΝΩΝ ΡΩΓΜΩΝ, ΗΤΟΙ ΤΑ ΦΑΙΝΟΜΕΝΑ ΤΗΣ ΚΑΜΠΥΛΩΣΕΩΣ, ΤΗΣ ΔΙΧΑΛΩΣΕΩΣ ΤΗΣ ΛΟΞΩΣΕΩΣ ΤΗΣ ΑΚΙΝΗΤΟΠΟΙΗΣΕΩΣ. ΣΕΙΡΑ ΠΕΙΡΑΜΑΤΩΝ ΑΠΟΔΕΙΚΝΥΕΙ ΟΤΙ Ο ΥΦΙΣΤΑΜΕΝΟΣ \"ΚΑΤΑ ΥΟΤΤΕ\" ΤΡΟΠΟΣ ΕΦΑΡΜΟΓΗΣ ΤΩΝ ΜΑΚΡΟΣΚΟΠΙΚΩΝ ΚΡΙΤΗΡΙΩΝ ΘΡΑΥΣΕΩΣ ΑΠΟΤΥΓΧΑΝΕΙ ΝΑ ΔΩΣΕΙΟΡΘΑ ΑΠΟΤΕΛΕΣΜΑΤΑ ΓΙΑ ΤΗΝ ΠΕΡΙΠΤΩΣΗ ΤΩΝ ΚΙΝΟΥΜΕΝΩΝ ΡΩΓΜΩΝ. ΠΡΟΤΕΙΝΕΤΑΙ, ΕΙΣΑΓΕΤΑΙ, ΘΕΜΕΛΙΩΝΕΤΑΙ ΚΑΙ ΕΦΑΡΜΟΖΕΤΑΙ ΝΕΟΣ ΔΙΔΥΜΟΣ ΤΡΟΠΟΣ ΕΦΑΡΜΟΓΗΣ ΤΩΝ ΚΡΙΤΗΡΙΩΝ, Ο ΟΠΟΙΟΣ ΔΙΝΕΙ ΑΠΟΤΕΛΕΣΜΑΤΑ ΠΟΥ ΤΑΥΤΙΖΟΝΤΑΙ ΑΠΟΛΥΤΑ ΣΧΕΔΟΝ ΜΕ ΤΑ ΠΕΙΡΑΜΑΤΙΚΑ ΑΠΟΤΕΛΕΣΜΑΤΑ. ΤΟ ΔΙΔΥΜΟ ΥΠΟΔΕΙΓΜΑ ΣΤΗΡΙΖΕΤΑΙ ΣΤΗΝ ΕΙΣΑΓΩΓΗ ΔΥΟ ΝΕΩΝ ΜΕΓΕΘΩΝ ΣΤΟ ΜΙΚΡΟΣΚΟΠΙΚΟ ΕΠΙΠΕΔΟ. ΣΤΗ ΣΥΝΕΧΕΙΑ ΕΡΕΥΝΩΝΤΑΙ ΤΑ ΓΕΝΕΣΙΟΥΡΓΑ ΑΙΤΙΑ ΤΩΝ ΩΣ ΑΝΩ ΦΑΙΝΟΜΕΝΩΝ ΩΣ ΣΥΝΑΡΤΗΣΗΣ ΤΩΝ ΠΕΡΙΞ ΤΗΣ ΡΩΓΜΗΣ ΔΗΜΙΟΥΡΓΗΜΕΝΩΝ, ΛΟΓΩ ΤΗΣ ΚΙΝΗΣΕΩΣ ΤΗΣ ΡΩΓΜΗΣ, ΑΝΙΣΟΤΡΟΠΩΝ."]},{"key":"dc:title","label":"Title","values":["ΦΑΙΝΟΜΕΝΑ ΑΣΤΑΘΕΙΑΣ ΤΗΣ ΔΙΕΥΘΥΝΣΕΩΣ ΤΑΧΕΩΣ ΚΙΝΟΥΜΕΝΩΝ ΡΩΓΜΩΝ","DIRECTIONAL INSTABILITY PHENOMENA FOR FAST RUNNING CRACKS"]}]}],"canonical_facts":{"dc:creator":["Κουρκούλης, Σταύρος","Kourkoulis, Stavros"],"dc:date":["1989"],"dc:description":["IN THE PRESENT DISSERTATION THE PHENOMENA OF DYNAMIC CRACK INSTABILITY ARE STUDIED FOR FAST RUNNING CRACKS. THESE PHENOMENA ARE: DYNAMIC BRANCHING, DYNAMIC CURVING, DYNAMIC KINKING AND CRACK ARREST. A SERIES OF EXPERIMENTS PROVES THAT THE EXISTING \"YOTTE MODE\" FOR APPLYING MACROSCOPIC FRACTURE CRITERIA FAILS TO GIVE CORRECT RESULTS IN THE CASE OF MOVING CRACKS. A NEW MODE FOR APPLYING THESE CRITERIA IS PROPOSED AND DESCRIBED IN THE SEQUEL. THIS MODE IS BASED ON THE INTRODUCTION OF TWO NEW QUANTITIES IN THE MICROSCOPIC LEVEL, AND ON THE HYPOTHESIS THAT THE CRACK FOR THE EARLYN STEPS OF ITS PROPAGATION IS MOVING IN THE FORM OFA TWIN SINGULARITY. THE RESULTS OF THE APPLICATION WITH EXPERIMENTAL EVIDENCE.IN THE SEQUEL THE SOURCES OF THE ABOVE MENTIONED PHENOMENA ARE INVESTIGATED ASRESULTS OF THE LOCAL ANISOTROPIES AROUND THE MOVING CRACK-TIP CAUSED BY THE MOVEMENT OF THE CRACK.","ΣΤΗΝ ΠΑΡΟΥΣΑ ΔΙΑΤΡΙΒΗ ΜΕΛΕΤΩΝΤΑΙ ΤΑ ΦΑΙΝΟΜΕΝΑ ΑΣΤΑΘΕΙΑΣ ΤΗΣ ΔΙΕΥΘΥΝΣΕΩΣ ΤΑΧΕΩΣ ΚΙΝΟΥΜΕΝΩΝ ΡΩΓΜΩΝ, ΗΤΟΙ ΤΑ ΦΑΙΝΟΜΕΝΑ ΤΗΣ ΚΑΜΠΥΛΩΣΕΩΣ, ΤΗΣ ΔΙΧΑΛΩΣΕΩΣ ΤΗΣ ΛΟΞΩΣΕΩΣ ΤΗΣ ΑΚΙΝΗΤΟΠΟΙΗΣΕΩΣ. ΣΕΙΡΑ ΠΕΙΡΑΜΑΤΩΝ ΑΠΟΔΕΙΚΝΥΕΙ ΟΤΙ Ο ΥΦΙΣΤΑΜΕΝΟΣ \"ΚΑΤΑ ΥΟΤΤΕ\" ΤΡΟΠΟΣ ΕΦΑΡΜΟΓΗΣ ΤΩΝ ΜΑΚΡΟΣΚΟΠΙΚΩΝ ΚΡΙΤΗΡΙΩΝ ΘΡΑΥΣΕΩΣ ΑΠΟΤΥΓΧΑΝΕΙ ΝΑ ΔΩΣΕΙΟΡΘΑ ΑΠΟΤΕΛΕΣΜΑΤΑ ΓΙΑ ΤΗΝ ΠΕΡΙΠΤΩΣΗ ΤΩΝ ΚΙΝΟΥΜΕΝΩΝ ΡΩΓΜΩΝ. ΠΡΟΤΕΙΝΕΤΑΙ, ΕΙΣΑΓΕΤΑΙ, ΘΕΜΕΛΙΩΝΕΤΑΙ ΚΑΙ ΕΦΑΡΜΟΖΕΤΑΙ ΝΕΟΣ ΔΙΔΥΜΟΣ ΤΡΟΠΟΣ ΕΦΑΡΜΟΓΗΣ ΤΩΝ ΚΡΙΤΗΡΙΩΝ, Ο ΟΠΟΙΟΣ ΔΙΝΕΙ ΑΠΟΤΕΛΕΣΜΑΤΑ ΠΟΥ ΤΑΥΤΙΖΟΝΤΑΙ ΑΠΟΛΥΤΑ ΣΧΕΔΟΝ ΜΕ ΤΑ ΠΕΙΡΑΜΑΤΙΚΑ ΑΠΟΤΕΛΕΣΜΑΤΑ. ΤΟ ΔΙΔΥΜΟ ΥΠΟΔΕΙΓΜΑ ΣΤΗΡΙΖΕΤΑΙ ΣΤΗΝ ΕΙΣΑΓΩΓΗ ΔΥΟ ΝΕΩΝ ΜΕΓΕΘΩΝ ΣΤΟ ΜΙΚΡΟΣΚΟΠΙΚΟ ΕΠΙΠΕΔΟ. ΣΤΗ ΣΥΝΕΧΕΙΑ ΕΡΕΥΝΩΝΤΑΙ ΤΑ ΓΕΝΕΣΙΟΥΡΓΑ ΑΙΤΙΑ ΤΩΝ ΩΣ ΑΝΩ ΦΑΙΝΟΜΕΝΩΝ ΩΣ ΣΥΝΑΡΤΗΣΗΣ ΤΩΝ ΠΕΡΙΞ ΤΗΣ ΡΩΓΜΗΣ ΔΗΜΙΟΥΡΓΗΜΕΝΩΝ, ΛΟΓΩ ΤΗΣ ΚΙΝΗΣΕΩΣ ΤΗΣ ΡΩΓΜΗΣ, ΑΝΙΣΟΤΡΟΠΩΝ."],"dc:identifier":["10.12681/eadd/1138","http://hdl.handle.net/10442/hedi/1138"],"dc:language":["gre"],"dc:publisher":["Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ)","National Technical University of Athens (NTUA)"],"dc:subject":["(DYNAMIC) CRACK BRANCHING","(DYNAMIC) CRACK CURVING","(DYNAMIC) CRACK PATH INSTABILITY","(DYNAMIC) CRACKKINKING","(ΔΥΝΑΜΙΚΗ) ΔΙΧΑΛΩΣΗ ΡΩΓΜΩΝ","(ΔΥΝΑΜΙΚΗ) ΛΟΞΩΣΗ ΡΩΓΜΩΝ","CRACK ARREST","CRACK PROPAGATION CRITERIA","DYNAMIC MODULES OF ELASTICITY","DYNAMIC STRESS FIELD","DYNAMIC STRESS INTENSITY FACTOR","ΑΚΙΝΗΤΟΠΟΙΗΣΗ ΡΩΓΜΩΝ","ΑΣΤΑΘΕΙΑ ΤΗΣ ΔΙΕΥΘΥΝΣΕΩΣ ΤΩΝ ΡΩΓΜΩΝ","ΔΥΝΑΜΙΚΟ ΜΕΤΡΟ ΕΛΑΣΤΙΚΟΤΗΤΑΣ","ΔΥΝΑΜΙΚΟ ΤΑΣΙΚΟ ΠΕΔΙΟ","ΔΥΝΑΜΙΚΟΣ ΣΥΝΤΕΛΕΣΤΗΣ ΕΝΤΑΣΕΩΣ ΤΩΝ ΤΑΣΕΩΝ","ΚΡΙΤΗΡΙΑ ΔΙΑΔΟΣΕΩΣ ΡΩΓΜΩΝ","Engineering and Technology","Mechanical Engineering","Επιστήμες Μηχανικού και Τεχνολογία","Επιστήμη Μηχανολόγου Μηχανικού"],"dc:title":["ΦΑΙΝΟΜΕΝΑ ΑΣΤΑΘΕΙΑΣ ΤΗΣ ΔΙΕΥΘΥΝΣΕΩΣ ΤΑΧΕΩΣ ΚΙΝΟΥΜΕΝΩΝ ΡΩΓΜΩΝ","DIRECTIONAL INSTABILITY PHENOMENA FOR FAST RUNNING CRACKS"],"dc:type":["PhD Thesis"]},"updated_at":"2026-07-24T02:24:46Z"}