An acoustic emission source localization approach based on time-reversal technology for additive manufacturing

The metal additive manufacturing process can inevitably lead to a great temperature gradient in the workpiece. Therefore, the thermal stress deformation and defects seriously affect the processing quality. In this paper, an array acoustic probe is designed on the base plate with the consideration of the time reversal technology. Corresponding simulations is implemented, which are designed to verify the ability of detecting and positioning the workpiece stress release acoustic emission signal. The simulation results demonstrate that the proposed method can position and monitor the random acoustic emission.

ACOUSTIC EXPRESS ANALYSIS OF QUALITATIVE AND QUANTITATIVE COMPOSITION OF SOILS DURING CONSTRUCTION WORKS

An express analysis of the ecological state of the soil during construction works is proposed. The algorithm is considered, which is the first approximation for describing the quality of the soil mixture, serving to build a system of operational recognition of the component composition of the soil mixture and the percentage of its main components. It is based on the analysis of the forced acoustic emission signal in the frequency domain to obtain the Fourier spectrum. From the general spectrum of the signal, consisting of a set of basic and higher (timbre) harmonics, subspectrs of significant basic harmonics corresponding to certain elements of the soil mixture are distinguished. To isolate the sub-spectra, a sequence of modal harmonics is used. The composition of the set of modal harmonics determines the qualitative composition of the soil in the first approximation.

Method for prediction of EMI Emissions from Automotive Ethernet to Vehicle Antennas

In automotive application new point-to-point (P2P) wideband communication systems e.g. Automotive Ethernet 100BASE-T1 imply an increasing effort in safeguarding its electromagnetic compatibility (EMC). The state-of-the-art EMC safeguarding process proposes a pre-compliant system level test before the vehicle level test, which may have significant variation in test results due to the different electromagnetic environment. This work presents an approach to calculate the emission signal at the vehicle antenna from the ECU output signal given by the power spectral density (PSD) of the Automotive Ethernet ECUs. The determination is performed via a transfer function which describes the coupling between the Ethernet wire harness and the antenna. This approach considers the modelling of the complex vehicle environment by the transfer function which promises the determination of an accurate emission signal before performing the vehicle level test. Further, the transfer function for a specifically EMC critical cable harness routing along the cockpit area is analyzed in more detail with a 3D simulation, which validates the chosen measurement technique of the transfer function.

The Wear Detection of Mill-Grinding Tool Based on Acoustic Emission Sensor

The monitoring of tool wear plays an important role in improving the processing efficiency and reducing the production cost of enterprises. This paper is focused on the detection of electroplated diamond mill-grinding tools by using the acoustic emission sensor. The wear stages of mill-grinding tools are divided into three parts, namely initial wear stage, normal wear stage, and severe wear stage. The characteristic parameter method and the waveform analysis method are applied to analyze the acoustic emission signals. The wear characteristics of the tool and workpiece in different wear stages are observed and analyzed. The results indicate that the acoustic emission waveform is relatively stable in the initial wear stage, and the continuous acoustic emission signal is dominated. Moreover, the diamond abrasive grains are mainly worn and slightly broken in the normal wear stage, and there are some pits on the machined workpiece surface after the initial wear stage. In the severe wear stage, most of the abrasive grains are broken or broken in a large area, and there are burst acoustic emission signals in the waveform.

Estimation of Probability Distributions of Geoacoustic Signal Characteristics

The paper presents an estimation of probability distributions of geoacoustic signal characteristics. The studied signals have a pulsed nature. The ones have been recording at the geodynamic test site of the IKIR FEB RAS (Kamchatka Peninsula) for more than 20 years. To estimate the distribution of characteristics, such time intervals were determined in which histograms of the distribution did not change. The following characteristics were chosen for the estimation: maximum amplitude, the position of pulse envelope maximum, duration, filling frequency, and pulse-to-pulse interval. The obtained estimates made it possible to develop an empirical model of the geoacoustic emission signal. The model can help to test new and existing algorithms for the processing and analysis of geoacoustic signals. The paper also shows that the formalization of the selected characteristics makes it possible to search for anomalies, including those associated with seismic events, by the characteristic variations.

Effect of Preliminary Irradiation of 321 Steel Substrates with High-Intense Pulsed Ion Beams on Scratch Test Results of Subsequently Deposited AlN Coatings

The paper presents the effect of irradiation of 321 steel substrates with a high-intense pulsed ion beam (HIPIB) on changes in functional properties of the surface layers and tribological characteristics of AlN coatings subsequently deposited above by the reactive magnetron sputtering method. The morphology of the modified surface layers, their microhardness and free surface energy levels are presented for different HIPIB energy densities. HIPIB irradiation of the substrates caused variations in the results of scratch tests combined with the acoustic emission signal processing. Their analysis has enabled concluding that the crack initiation threshold could be at least doubled for the studied coating/substrate system due to preliminary HIPIB irradiation. Finally, the obtained data were discussed, and future research directions were proposed.