Experimental study of electromechanical measurement, surface analysis and corrosion inhibition of mild steel in 1M HCL by Schiff’s bases (SBs)

Potentiodynamic polarization measurements indicate that SBs acts as mixed type corrosion inhibitors. the morphology of the mild steel surface is investigated by scanning electron microscopy (SEM) and the surface composition was evaluated using energy-dispersive X-ray Spectroscopy (EDX) to show the presence of SBs on the mild steel surface in 1M HCL. The present study, three Schiff’s bases (SBs) namely 2 (2-hydroxybenzylideneamino) heptanedioic acids, 2 (4-dimethylamino benzlideamino) heptanedioic acids and 2 (4hydroxy-3-methoxybenzylideneamino) heptanedioic acids were synthesized. Using weight loss, potentiodynamic polarization and electromechanical impedance spectroscopy (EIS) techniques for corrosion inhibition properties on mild steel in 1M HCL has been investigated. The adsorption of SBs on the mild steel surface contains Langmuir adsorption isotherm. Here kinetic and thermodynamic parameters also determined to describe the mechanism of adsorption in relevance. The main object of this presentation is experimental study of the inhibiting action of synthesized Schiff’s bases of aldehydes containing nitrogen, oxygen and aromatic rings and Glutamic acid.

In-plane selective excitation of arbitrary vibration modes using thickness-shear (d15) piezoelectric transducers

Experimental modal analysis (EMA) is of great importance for the dynamic characterization of structures. Existing methods typically employ out-of-plane forces for excitation and measure the acceleration or strain for modal analysis. However, these methods encountered difficulties in some cases. In this work, we proposed an in-plane excitation method based on thickness-shear (d15) piezoelectric transducers. Through the combination of distributed d15 PZT strips, arbitrary vibration modes can be selectively excited in a wide frequency range. Both simulations and experiments were conducted and the results validated the proposed method. Specifically, bending, torsional, and longitudinal vibration modes of a rectangular bar were selectively excited. Torsional modes of a shaft were excited without the aid of brackets and bending modes of a circular plate were excited with actuators placed at nodal lines. Furthermore, the electromechanical impedance of the PZT-structure system was measured from which the natural frequency and quality factor were directly extracted. Due to its simplicity and flexibility, the proposed vibration excitation method is expected to be widely used in near future.

Curing monitoring of bonded composite patch at constant temperature with electromechanical impedance and system parameters evaluation approach

As one of cost-effective maintenance methods, bonded composite patch repair has been receiving more and more attention in the engineering community since past decades. However, realizing real-time monitoring for curing process of bonded repair patch is difficult for most current techniques. In our work, a method based on electromechanical impedance and system parameters evaluation for structural health monitoring issues was developed, which could implement the online monitoring throughout whole curing process. Compared with the dynamic thermomechanical analysis results, the experiment data matches well. It demonstrates that the proposed approach can effectively monitor the curing process of composite repair patch at a constant temperature of 120 °C. Hence, the presented approach in this paper is expected to be a novel, robust, and real-time monitoring method for structural maintenance with the composite patch.

An Experimental Study of Damage Detection on Typical Joints of Jackets Platform Based on Electro-Mechanical Impedance Technique

Many methods have been used in the past two decades to detect crack damage in steel joints of the offshore structures, but the electromechanical impedance (EMI) method is a comparatively recent non-destructive method that can be used for quality monitoring of the weld in structural steel joints. The EMI method ensures the direct assessment, analysis and particularly the recognition of structural dynamics by acquiring its EM admittance signatures. This research paper first briefly introduces the theoretical background of the EMI method, followed by carrying out the experimental work in which damage in the form of a crack is simulated by using an impedance analyser at different distances. The EMI technique is used to identify the existence of damage in the welded steel joints of offshore steel jacket structures, and Q345B steel was chosen as the material for test in the present study. Sub-millimetre cracks were found in four typical welded steel joints on the jacket platform under circulating loads, and root average variance was used to assess the extent of the crack damage.