This paper deals with possibilities of acoustic emission method utilization as an online surveillance tool for improvement of identification of structural damage onset in composite materials. With employment of AE method we are able to localize the degraded areas in stressed components and subsequently estimate the extent of degradation. In experimental part the piezoelectric sensor was employed for continuous record of emission signals, continuous processing and analysis of measured data and monitoring of stressed material feedback on applied mechanical load in real time. Partial results from distinctive areas of conducted research were implemented in this method, especially detection of emission signals and analysis of recorded signals in both frequency and temporal zones. Samples were reinforcement of 6 layers aramide-carbon weave 0/90° of specific mass 180 g/m2.In total 7 samples were tested in monoaxial tension on universal testing apparatus ZDM 5/51 with acoustic emission measurement recording in course of testing.
The work is focused effect of different temperature nozzle in additive manufacturing process FFF (Fused Filament Fabrication) technology for the most common materials (PLA, PETG and ABS). A standard specimen internal structure arranged ±45° in longitudinal print direction with 100% infill. For the exact testing are used no perimetres. The specimens were printed by minimal, middle and maximum nozzle temperature. Temperature range is given by the filament company. To ensure relevant testing materials from the same company in one colour were used. A printed specimens were testing by destructive testing method on tensile testing machine. For testing were made five specimens in one setting. Finally, were made 45 specimens for tensile testing.
The mechanical behavior of eggshell was determined in terms of average rupture force and corresponding deformation. For the experiment, we selected goose eggs (Anser anser f. domestica). Samples of eggs were compressed along their x-axis and z-axis. The effect of the loading orientation can be described in terms of the eggshell contour curvature. Two different experimental methods were used: compression between two plates (loading rates up to 5 mm/s) and the Hopkinson split pressure bar technique. This second method enables achieving loading rates up to about 17 m/s. The response of goose eggs to this high loading rate was characterized also by simultaneous measurement of the eggshell surface displacements using a laser vibrometer and by the measurement of both circumferential and meridian strains. Keywords Eggs . Compression . Dynamic loading . HSPB technique . Rupture forceThe egg is a packaged food. One of the important quality aspects of packaged eggs is the mechanical strength of the egg shell [1]. Breaking of the eggshell is due to the forces acting on the eggs under static and/or quasi-static conditions, as at the bottom of the pile of loaded trays, but the greatest part occurs under dynamic conditions, e.g., when an egg falls on to the cage bottom at oviposition and in the many other events, which are collected by Carter [2]. The dynamic loading can also lead to the vibration of the egg liquid products. The eggs thus serve
The publication focuses on tensile strength testing of samples produced by additive Fused Filament Fabrication technology. Four materials PLA, rPLA, PETG and rPETG were tested. The polymeric materials are PLA (polylactic acid), PETG (polyethylene terephthalate glucol) and recyclates of these materials. The materials were made into samples for tensile testing according to ASTM D638. Tensile diagrams were created from the measured data. Statistical processing and comparison of the measured data is performed in the publication. Two groups of materials were compared. Recycled polymeric materials and virgin polymeric materials. In the discussion, a comparison of the mechanical properties of recycled materials for 3D printing versus virgin materials for 3D printing by Fused Filament Fabrication technology is made.
This article deals with the spread of corrosion in material at different exposure times, and its effect on the measured brittle fracture and notch impact strength under different temperature conditions. To assess the degradational effect of corrosion on the material characteristics represented by the measured impact strength, we conducted a fractographic analysis of fracture surfaces, the aim of which was to evaluate the spread of corrosion in the material. In the first part of the experiment, two corrosion tests are simulated with a duration time of 432 and 648 hours, to compare the degradation effect of corrosion on the notch impact strength, depending on the duration of the corrosion tests. The following part shows the results of the impact bending test, where the experiment was conducted in an area of reduced and increased temperatures. The final part summarizes the results of the fractographic analysis of sample fracture surfaces from the impact bending tests. Based on the measured the length of the corrosion cracks, we analyzed the sample at the notch and from the material surface after the impact bending test.
This work deals with a specific method of non-destructive testing -acoustic emission. The theoretical part of the article is focused on the underlying principle of this method and its applicability. The experimental part is focused on the research of pressure resistance in mineral feed using acoustic emission. Mineral feed is a condensed cube of rock salt (sodium chloride) with supplementary minerals, which is fed to livestock and game to supply the mineral elements necessary for their health and condition. Acoustic emission gives the overview of internal changes in material structure. With use of specific software we can interpret the acoustic signal and identify the current state of material integrity in real time.
The article deals with the use of acoustic emission to identify the formation of cracks during the mechanical loading in the corrosive attacked weldment S235JR+N. The experiment includes the methodology for continual record of emissive signals, data analysis and monitoring of material response to monitor mechanical stress effect in real time. There is possibility to observe response of corrosive degraded samples in real time during mechanical stress through the suitably designed methodology of detection, process and analysing of acoustic emission signals. It is possible to gain new information about processes rising inside the material by this way of data measurement. The signals of acoustic emission can be used as the way of identification for the micro cracks rising in the inner and also external structure of effortful materials.
The objective of this paper was to investigate and respond to the quality and strength of CMT welds that were subjected to degradation effects and subsequently to tensile testing. The tensile test was recorded using AE acoustic emission. The experiment focused on the quality of CMT welds (Cold Metal Transfer) and the resistance of these welds to corrosion degradation. Welds are generally exposed to environmental influences such as high stress, stress and degradation effects. The combined effect of these factors may in some cases result in the destruction of weld joints. For this reason, emphasis is placed on the quality of welds and their resistance to environmental influences. For this measurement there were ten samples prepared, divided into two groups, each having five samples. One group was subjected to corrosion degradation, while the other one was at the same time subjected only to environmental influences. Subsequently, all samples were subjected to tensile testing. The course of this test was recorded using the AE acoustic emission, where the AE sensor was attached to each weldment to record dislocations during the tensile test. Named values were evaluated in the Dakel-Daeshow program.
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