The effect of an electromagnetic peening process on mumetal properties
Peening processes are widely used in the industries to enhance the performance of the most solicited parts of mechanical pieces. Actual processes, like shot peening and low plasticity burnishing, are quite limited to a small depth of treatment circa 1 mm at maximum. A new process is developed based on pulsed electromagnetic fields. This method allows a better depth of treatment up to 5 mm and it can be easily monitored. A prototype was developed using a pulse current generator and specifically designed inductor. This prototype was used on mumetal for the preliminary tests. Indeed, its maximal permeability and coercivity are highly impacted by the presence of stresses. Using specifics sensors, some changes occur after treatment on mumetal samples and can be observed.
Needle-probe techniques for local magnetic flux measurements
Numerical two-dimensional field investigations in the cross section of laminated nonoriented electrical steel sheet are performed in order to verify the possibilities and limitations of the two needle-probe technique for the measurement of local magnetic flux near the cutting edge. If one of the needles approaches the lamination edge or when inhomogeneities are present in the flux distribution along the strip width due to magnetic properties altered by the cutting procedure, then the signal from the needle probes no longer represents the flux through a rectangular surface under the needles because of E-field components perpendicular to the lamination surface. The flux calculated from the needles is compared to the actual flux passing through the rectangular surface under the needles and corresponding correction factors as a function of the needle position away from the cutting edge are computed. Depending on the positioning method, the needle probes can give an under- or overestimation of the actual flux....
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.