|
| |
|
|
Analýza porušení systému matrice – vlákno
Klusák, Jan ; Knésl, Zdeněk
Conditions of damage initiation in fibre composite materials are analysed in the paper. The main objective of the presentation is to quantify the influence of fibre-matrix material mismatch on failure critical stress under which a crack is initiated in the vicinity of a free fibre end. The considerations are derived from the knowledge of the stress state caused by the existence of the bi-material interface. The step change of material properties in the interface leads to singular peak of stresses, which may be responsible for crack initiation and consequently for failure of the structure. The singular stress state near the interface is analysed by means of generalized linear elastic fracture mechanics and conditions of crack initiation are assessed. On the basis of the results the question of interfacial debonding between the fibre and matrix is discussed.
|
|
| |
|
|
Rozvoj kuželových trhlin při "Ball on the Three Balls Test"
Chlup, Zdeněk ; Harrer, W. ; Kozák, Vladislav ; Řehořek, Lukáš
Proposed ball on three balls test takes advantage of biaxial loading and very simple experimental setup allowing usage of various test-piece geometries. The loading configuration is insensitive to small inaccuracies of disk shape. The only relevant parameter playing significant role is the thickness of test-piece. The three supporting and one loading balls eliminate disadvantage of ring of ring test mentioned above. From the experiences of numerical analyses as well as experimental results is still unclear influence of contact stresses between test-piece and loading ball on resulting stress field respectively the influence of cone crack developed due to such stresses. The main aim of this paper is to describe possibility of cone crack development due to contact stresses.
|
|
| |
|
| |
guest ::
