Search results for "Acoustic Emission"
showing 10 items of 56 documents
Elastoplastic Damaging Model for Adhesive Anchor Systems. II: Numerical and Experimental Validation
2011
This paper presents the numerical and experimental validation of the analytical elastoplastic damaging model proposed in the companion paper (Part I). The validation was carried out by describing the pullout failure of epoxy adhesive anchors. Pullout tests were simulated numerically and performed experimentally. Several specimens made of a rebar embedded in a hardened concrete cylinder by means of polyester resin were tested. Conventional strain gauges and acoustic emission (AE) sensors were used to evaluate the structural response of the system and to monitor the onset and progression of structural damage, respectively. The parametric analysis and the moment tensor analysis of the AE data …
Investigation on fracture of epoxy-filled composites by acoustic emission
2016
Acoustic emission (AE) technique is widely used to monitor failure processes in composite materials includ-ing development of cracks and plastic deformations within the polymer matrix, fracture and debonding of inclusions, etc. In this study, the AE technique was applied investigating failure character of epoxy polymers with different content of nanofiller – fine polyethersulfone (PES) powder. Variation of material properties of the epoxy with 0, 5%, 7.5%, 10%, and 12.5% concentration (by weight) of the PES was assessed experimentally. Correlation between the PES content and the modulus of elasticity was found negligible. The same was characteristic for the tensile strength. Whereas, such a…
Keypoints to Successful Newborn Hearing Screening. Thirty Years of Experience and Innovations
2021
Congenital deafness is a major pediatric problem, affecting about 1.5–3 per 1000 newborns. The early treatment through cochlear implantation and auditory rehabilitation has been a historic milestone. Early diagnosis of congenital deafness is an essential requirement to obtain the best results, which is achieved through neonatal screening, a diagnostic practice that we began systematically at the Hospital Clínico in Valencia (Spain) 30 years ago. Neonatal hearing screening is successful in most developed countries. Its implementation has been slow due to the multiple difficulties that its universal application entails since it involves several health professionals and must be carried out, in…
Phase transitions in Ag-based solid electrolytes as detected by thermosonimetry
2001
Abstract Observations of the acoustic emission accompanying the solid–solid (polymorphic) phase changes in silver iodide and silver chalcogenides were performed. It has been found that the temperature dependencies of both the number of acoustic events and their counting rate, registered when heating the investigated materials, display distinct anomalies at the temperature corresponding to the polymorphic phase transition occurring in a given substance. The phase transition temperatures determined from the position of these anomalies agree well with the results of control DSC measurements, as well as with the literature data on the temperatures of the transition of investigated materials to …
Instantaneous root mean squire value of the acoustic emission as a means of measuring partial discharges
2003
The author presents the measurement results of the parameter A/sub RMS/ for three types of partial discharges (PDs) generated in a typical high-voltage system: on pressboard, on resin, and on glass. A typical run of A/sub RMS/ on an X-Y register is shown. It manifests a relatively stable instantaneous root mean square value of the electric signal converted from the acoustic signal as a function of time. Results obtained for the three surfaces demonstrate that the parameter A/sub RMS/ is perfectly suitable for characterizing PDs measured by the acoustic method. It is univocally connected with the energy of the generated PD. >
Acoustic Emission Monitoring of Chemically Bonded Anchors
2010
This paper presents a study on the use of acoustic emission (AE) to assess the structural soundness of concrete reinforced with chemically bonded anchors. The results of an experimental work based on six pullout tests monitored using an AE instrumentation suite are reported below. In every test one rebar was embedded in the hardened concrete by means of polyester resin. The AE was adopted to moni- tor the onset and progression of any structural damage. The parametric analysis, the intensity analysis and the moment tensor analysis of AE data were used to discriminate among different sources of damage. The technique shows promise for field application and may contribute to fully understand th…
Objectivization of the electrical discharge measurement results taken by the acoustic emission method
2006
The subject matter of this paper refers to the improvement of the acoustic emission method (AE) in its application for diagnostics of insulation systems of power appliances whereas the detailed subject matter is connected with determining the possibilities and indicating the range of using statistical and digital methods of signal processing for the evaluation of the AE pulses generated by partial discharges (PDs), which can occur in paper-oil insulation of power transformers.
The repeatability and reproducibility of calibrating signals generated by Hsu-Nielsen method
2005
During the measurements of the acoustic emission signals taken both in the laboratory and industrial conditions it is necessary to carry out calibration of the measurement paths used. One of the basic calibration methods is the one invented by Hsu-Nielsen, which consists in generating an acoustic signal during breaking a scriber placed in a special head put on an automatic pencil. The paper presents the measurement results of acoustic signals taken at various structural parameters of calibrating heads, which was done to determine their influence on the repeatability of the results obtained. Moreover, the measurements were taken for ten identical, in relation to their geometrical measurement…
Universal newborn hearing screening in the Italian Region of Sicily in 2018
2021
We have clarified the role of Universal Neonatal Hearing Screening (UNHS) for both early diagnosis and rapid treatment in order to improve the prognosis of the deaf child and reduce patient management costs. Although in Sicily UNHS has been progressively implemented, there is scarce data in the literature on this matter. Therefore, the main objective was to collect in the year 2018 the following data: number of newborns screened for hearing loss, number of infants "referred" to transiently evoked otoacoustic emissions (TEOAE), number of infants with pathologic auditory brainstem response (ABR) and number of infants affected by permanent hearing loss.UNHS monitoring was conducted through the…
Micromechanisms of load transfer in a unidirectional carbon fibre-reinforced epoxy composite due to fibre failures: Part 3. Multiscale reconstruction…
2008
International audience; This third article describes a multiscale process which takes into account the most important microscopic phenomena associated with composite degradation, including fibre fractures and interfacial debonding, overloading of fibres neighbouring a fibre break as well as viscoelastic behaviour of the matrix. The results have been used to accurately predict the macroscopic failure of unidirectional carbon fibre-reinforced epoxy and quantify damage accumulation in pressure vessels made of the same material. The approach described has allowed the acoustic emission activity resulting from fibres breaks to be evaluated and shown how the residual lifetimes of such vessels, whe…