Towards Electron-Beam-Driven Soft / Polymer Fiber Microrobotics for Vacuum Conditions

The possibility of creating vacuum robotics based on the polymer structures irradiated by an electron beam, in particular, polymer fibers, which provide high functional flexibility and a variety of states, is discussed. The possibility of using polymer fibers as different types of MEMS-like electromechanical elements is demonstrated - from elastic cantilevers to springs that change their state under the electron beam. Experimentally proved the presence of different functional types of fibers, correlating with their thickness, as well as the phenomenon of the fiber break. A number of exotic forms of dynamics have been demonstrated and a method for their detection has been developed using 2D Fourier spectra, integral spatial characteristics, time resolved correlograms and wavelet transforms (visualized as the scaleograms / scalograms). Access barcodes for the full video records of the corresponding experiments are provided.

Acoustic Emission Signal Due to Fiber Break and Fiber Matrix Debonding in Model Composite: A Computational Study

Acoustic emission monitoring is a useful technique to deal with detection and identification of damage in composite materials. Over the last few years, identification of damage through intelligent signal processing was particularly emphasized. Data-driven models are developed to predict the remaining useful lifetime. Finite elements modeling (FEM) was used to simulate AE signals due to fiber break and fiber/matrix debonding in a model carbon fiber composite and thereby better understand the AE signals and physical phenomena. This paper presents a computational analysis of AE waveforms resulting from fiber break and fiber/matrix debonding. The objective of this research was to compare the AE signals from a validated fiber break simulation to the AE signals obtained from fiber/matrix debonding and fiber break obtained in several media and to discuss the capability to detect and identify each source.

Damage Analysis of Composite CFRP Tubes Using Acoustic Emission Monitoring and Pattern Recognition Approach

The acoustic emission method has been adopted for detection of damage mechanisms in carbon-fiber-reinforced polymer composite tubes during the three-point bending test. The damage evolution process of the individual samples has been monitored using the acoustic emission method, which is one of the non-destructive methods. The obtained data were then subjected to a two-step technique, which combines the unsupervised pattern recognition approach utilizing the short-time frequency spectra with the boundary curve enabling the already clustered data to be additionally filtered. The boundary curve identification has been carried out on the basis of preliminary tensile tests of the carbon fiber sheafs, where, by overlapping the force versus time dependency by the acoustic emission activity versus time dependency, it was possible to identify the boundary which will separate the signals originating from the fiber break from unwanted secondary sources. The application of the presented two-step method resulted in the identification of the failure mechanisms such as matrix cracking, fiber break, decohesion, and debonding. Besides the comparison of the results with already published research papers, the study presents the comprehensive parametric acoustic emission signal analysis of the individual clusters.

In-situ photoconductivity measurement of imidazole in optical fiber break-junctions

We develop a method based on the mechanically controllable break junction technique to investigate the electron transport properties of single molecular junctions upon fiber waveguided light. In our strategy, a...

KARAKTERISASI KOMPOSIT MATRIK RESIN EPOXY BERPENGUAT SERAT GLASS DAN SERAT PELEPAH SALAK DENGAN PERLAKUAN NaOH 5%

Serat pelepah tanaman salak sebagai bahan komposit merupakan salah satu alternatif dalam pembuatan komposit secara ilmiah. Tujuan dari penelitian ini untuk mengetahui perbandingan kekuatan tarik dan mengetahui sifat fisik dari komposit serat glass dan serat pelepah salak dengan matrik resin epoxy dengan variasi fraksi volume serat. Sifat-sifat mekanik yang diperoleh yaitu kekuatan tarik, regangan, dan modulus elastisitas. Untuk mengetahui sifat fisik dari komposit melalui pengamatan foto makro dari penampang patahan spesimen uji tarik. Pembuatan benda uji komposit dengan proses hand lay-up menggunakan standar ukuran ASTM D 638M-84. Komposit dibuat dengan fraksi volume (94% resin dan 6% serat glass), (94% resin dan 6% serat pelepah salak), (94% resin, 3% serat glass dan 3% serat pelepah salak), ( 94% resin, 4% serat glass dan 2% serat pelepah salak), (94% resin, 2% serat glass dan 4% serat pelepah salak) dan matrik tanpa serat. Berdasarkan hasil penelitian yang telah dilakukan, dapat disimpulkan bahwa nilai kekuatan tarik maksimum diperoleh pada komposit fraksi volume 94% resin dan 6% serat glass sebesar 35,49 Mpa. Kekuatan tarik komposit terendah pada fraksi volume 94% resin dan 6% serat pelepah salak sebesar 14,90 Mpa. Nilai regangan tertinggi didapat pada komposit fraksi tanpa serat yaitu 34,66%. Penambahan serat berpengaruh pada modulus elastisitas komposit. Pada komposit fraksi volume 94% resin dan 6% serat glass memperoleh nilai modulus elastisitas paling tinggi yaitu 434,19 Mpa. Hasil foto makro yang terlihat pada spesimen adalah fiber break, fiber pull out, void dan matrik cracking. Kata kunci:epoxy, glass, komposit, pelepah salak, sifat mekanik, sifat fisik.