/pdf/a-review-of-surface-deformation-and-strain-measurement-using-3tb8linch1.pdf

A Review of Surface Deformation and Strain Measurement Using Two-Dimensional Digital Image Correlation

Characterising the behaviour of composite single lap bonded joints using digital image correlation

The Digital Image Correlation (DIC) technique enables full field, noncontact measurements of displacements and strains of a wide variety of objects. An adaptation of the DIC technique for monitoring of civil-engineering structures is presented in the paper. A general concept of the complex, automatic monitoring system, in which the DIC sensor plays an important role is described. Some new software features, which aim to facilitate outdoor measurements and speed up the correlation analysis, is also introduced. As an example of application, measurements of a railway bridge in Nieporet (Poland) are presented. The experimental results are compared with displacements of a FEM model of the bridge.

/pdf/monitoring-of-civil-engineering-structures-using-digital-17bllwrs6u.pdf

Monitoring of civil engineering structures using Digital Image Correlation technique

Laboratorial test monitoring applying photogrammetric post-processing procedures to surface displacements

Conventional deformation measurement techniques, such as utilizing a LVDT, a demountable mechanical strain gauge (demec gauge), and an electrical strain gauge, despite their vast usage in experimental studies, suffer several disadvantages, including high cost, time-consuming specimen preparation, and the inability to obtain the whole displacement or strain fields. The aforementioned drawbacks on one hand and the importance of deformation measurements in all civil engineering laboratory tests on the other hand have led researchers to develop other measurement techniques, especially image-based techniques, capable of evaluating whole deformation fields. Among all of these recently developed methods, particle image velocimetry (PIV) has attracted much interest in all branches of civil engineering experimental investigations; PIV is a powerful image-based technique for evaluating both displacement and strain fields by analyzing successive digital images of a field undergoing deformation. Despite its g...

Displacement and Strain Field Measurement in Steel and RC Beams Using Particle Image Velocimetry

Optical strain gauge vs. traditional strain gauges for concrete elasticity modulus determination

The solder joint fatigue lifetime of a VQFN package in non-standard Power Cycling on Board (PCoB) accelerated stress tests is identified to significantly depend on the ambient temperature at which the PCoB test is conducted. Lifetime models based on the experimental data obtained at 80°C ambient temperature would overestimate the lifetime for PCoB tests performed at 110°C ambient temperature. Thermo-oxidative aging of the molding compound (MC), found in samples after exposure to PCoB tests, induces higher loading on the solder joint and worsens the solder joint fatigue lifetime in PCoB tests. The influence of thermally aged MC on solder joint fatigue is investigated by explicitly considering an aged MC layer in the finite element (FE) modelling. Simulation confirms that the aged MC layer changes the loading of the solder joints: it induces additional stress on the solder joint when compared to pristine packages, especially when the temperature of the molding compound in the PCoB test becomes higher than the glass transition temperature Tg. Considering the aged MC layer in the FE simulation permits to establish a solder joint fatigue prediction framework, which is able to cover both the 80°C and the 110°C ambient test temperatures.

Y.S. Chan

Papers

Optical strain gauge vs. traditional strain gauges for concrete elasticity modulus determination

Investigation of the impact of thermal aging of molding compounds on the solder joint fatigue of a VQFN package