the present study utilizes an analytical method to formulate the three lowest modal frequencies of axially-loaded notched beam through both crack location and load level in a specific format that can be used in existing frequency-based crack-identification methods. the proposed formula provides a basis to shift into two states, one with axial loading and the other without any loading whatsoever...

The vibration behavior of an atomic force microscope [AFM] cantilever with a crack during the nanomachining process is studied. The cantilever is divided into two segments by the crack, and a rotational spring is used to simulate the crack. The two individual governing equations of transverse vibration for the cracked cantilever can be expressed. However, the corresponding boundary conditions a...

Two themes form the basis of this study on fibre reinforced laminated composites: namely 'thermal residual stress' and 'transverse cracking'. Thermal residual stresses are inherent to any composite structure and are internal stress within the structure that form during manufacture. Their formation arises from the difference in coefficient of thermal expansion of the fibre and the matrix. These ...

In a continuous fiber reinforced brittle matrix composite, the transverse fracture is often dominated by the crack trapping and bridging effects as well as the fiber breakage. In this article, the toughening effect of flat fiber bundles with the cross-sectional aspect ratio, , ranging from 0.05 to 5 is discussed in the context of energy analysis. With a constant size/spacing ratio of the fiber ...

Crack propagation across interlayers separating adjoining brittle plates in flexure was studied using a model glass/epoxy/glass system. A transverse starter crack in the center glass plate was made to propagate to the nearest epoxy interface, where it arrested. System failure occurred at some higher load by crack reinitiation from pre-existing flaws in the adjoining glass surface, not by contin...

Abstract A simple method is proposed to model the open cracked beam structures. In this method, crack is modeled as a beam element. Hence cracked beam can be assumed to be a beam with stepped cross sections, and problem of determining natural frequency and mode shape of cracked beam, can be solved as determining these characteristics for a beam with different length and cross section. With this...

In this study, the vibration of cracked plates is investigated using the differential quadrature method and experimental modal analysis. The crack, which is assumed to be open, is modeled by the extended rotational spring. With its finite length, the crack divides the plate into six segments. Then, the differential quadrature is applied to the governing differential equations of motion and the ...

In this study, fracture toughness of North American elk (Cervus elaphus canadensis) antler and bovine femur were measured using four-point bending tests on single-edge notched compact samples (ASTM C1421). Tests were conducted on crack growth directions longitudinal and transverse to the long axis of antler and bone in both dry and hydrated conditions to study the effects of fiber orientation a...

In this paper the line-spring model developed by Rice and Levy is used to obtain an approximate solution for a cylindrical shell containing a part-through surface crack. It is assumed that the shell contains a circumferential or axial semi-elliptic internal or external surface crack and is subjected to a uniform membrane loading or a uniform bending moment away from the crack region. To formula...