摘要:

This paper provides an overview of cyclically loaded structures and experimental investigation techniques. The chemical composition and mechanical characteristics of the steels that crane secondary trusses and transporter cranes are made of are presented.Relative levels of the basic compressive and tensile stresses at truss chords and deck girder members are presented. The most heavily loaded parts of structures with possible fatigue crack formation have been revealed. It has been found that the indication of the presence of considerable fatigue deterioration is an elevated deformability of a structure or a change of its deformation diagram.

ISSN:1058-9759    

DOI:10.1080/10589750008953060

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A feasibility study is made to search if lock-in thermography can be usefully employed in non-destructive evaluations of different materials of industrial interest. Several specimens, made of different materials and with defects artificially created to simulate either delaminations, or cracks, or inclusions of spurious materials, are considered. Results prove that lock-in thermography is able to give information about thermophysical properties of materials as well as to detect defects and to determine their size, depth and nature in a quick and simple way. Some aspects linked to the use, fields of application and limitations of the technique are also discussed.

ISSN:1058-9759    

DOI:10.1080/10589750008953061

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Detection of cracks near sharp edges is a challenging problem in eddy current inspection of metal parts and structures, especially in the aircraft industry. This is because the edge itself causes a strong disruption of the eddy current flow in the crack region. With conventional probes, the large signal due to the edge can completely mask that produced by the crack. An effective solution for separating the two signals is the use of an eddy current probe comprising a giant magnetoresistive (GMR) sensor placed in the center of a pancake-type excitation coil. The sensor detects only the magnetic field along its sensitive axis and is not influenced by fields applied in perpendicular directions. By orienting the sensitive axis parallel to the edge direction, the edge signal is eliminated. Moreover, in this measuring configuration, the presence of the edge enhances the crack signal, leading to higher sensitivity and improved spatial resolution for edge cracks as compared to inside cracks. Measurement of surface edge cracks of 1 mm length and 0.5 mm depth as well as small sub-surface edge defects are presented. The enhanced sensitivity of this probe to edge cracks is explained using a qualitative interpretation of experimental results based on the schematic representation of eddy current flow in the specimen.

ISSN:1058-9759    

DOI:10.1080/10589750008953062

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Distinction among various silicate glasses with different boron bond structure is an important practical issue in the glass making industry. To this end, it has been suggested that microwave dielectric property characterization may be a useful tool to distinguish among these glasses since in the past this technique has shown the potential for characterizing different types of materials via their dielectric properties. Therefore, an existing 2-port transmission line measurement technique, using an HP8510B network analyzer, is used to measure the dielectric properties of four different types of glass specimens. These electrical properties are measured over a wide band of microwave frequencies covering X- and Ku-band (8.2 GHz-18 GHz). The results indicate that each glass specimen with its own specific chemistry (different boron chemistry) has distinct dielectric properties as function of frequency. It is also shown that these specimens can be easily distinguished from one another when inspected by an open-ended rectangular waveguide aperture probe for on-line, real-time and non-eontact testing of thin glass sheets.

ISSN:1058-9759    

DOI:10.1080/10589750008953063

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor