Dynamic analysis of two collinear electro-magnetically dielectric cracks in a piezoelectromagnetic material is made under in-plane magneto-electro-mechanical impacts. Generalized semi-permeable crackface boundary conditions are proposed to simulate realistic opening cracks with dielectric. Ideal boundary conditions of a combination of electrically permeable or impermeable and magnetically perme...

Hydraulic fracturing (HF), as a stimulation technique in petroleum engineering, has made possible the oil production from reservoirs with very low permeability. The combination of horizontal drilling and multiple HF with various perforation angles has been widely used to stimulate oil reservoirs for economical productions. Despite the wide use of HF, there are still ambiguous aspects that requi...

Introduction: Results from Mars Odyssey's highenergy neutron spectrometer, and gamma ray spectrometer have shown that there is 15 to 20% ice in the top meter of Martian regolith at latitudes of +/-55 degrees [1,2,3]. This observation has been critical in understanding the nature of patterned ground on Mars [4]. The resolution of the ground ice maps generated from these instruments, however, is ...

The vast amount of data generated by automated surface distress evaluation equipment far exceeds the storage capabilities of current digital data storage systems. A study using fractals is being carried out to alleviate the data storage problem, since fractal image compression offers the largest compression ratio of the available image compression algorithms. This paper discusses the use of fra...

Each year, millions of dollars are invested on road maintenance and reparation all over the world. In order to minimize costs, one of the main aspects is the early detection of those flaws. Different types of cracks require different types of repairs; therefore, not only a crack detection is required but a crack type classification. Also, the earlier the crack is detected, the cheaper the repar...

Ultrasonic testing for fatigue crack detection in metallic members are commonly performed using time domain analysis of Rayleigh waves. This approach will be successful only if the fatigue cracks produce strong interaction with the Rayleigh waves. The optimum frequency range of ultrasonic Rayleigh waves for scanning long structural members in the field is from 0.5 to 2.25 MHz because higher fre...

Concrete is usually highly alkaline (pH around 12), thus protecting reinforcement against corrosion. The occurrence of oxides is favored when the medium pH surrounding the bar is in values near to 9 or lower. Aggressive substances for reinforcements generally enter concrete through its pore structure, and cracks tend to decrease pH, stimulating corrosion process. There are several causes for cr...

Rotating machinery, such as steam turbo, compressor, and aeroengine etc., are widely used in many industrial fields. Among the important rotor faults, the fatigue crack fault, which can lead to catastrophic failure and cause injuries and severe damage to machinery if undetected in its early stages, is most difficult to detect efficiently with traditional methods. In the paper, based on the trut...

The practical problem. In many practical situations, it is extremely important to be able to detect hidden cracks (and other possible faults) in aerospace and other structures. One way of testing the structural integrity of such structures is by using ultrasonic waves. For thin plates, Lamb waves (which direct the energy along the plate) are especially useful. To use these waves, we set up a tr...

This study proposes a new non-contact approach allows detecting, measuring and tracking the change of cracks in the historical structure using photogrammetric techniques and computer methods. The proposed procedure used an accurate generation of true orthophoto of the studied structure using precise 3D surface representations derived from laser scanning and several digital images that entirely ...