Fiber Welding Research Articles

Process variables that control natural fiber welding: time, temperature, and amount of ionic liquid

A systematic study of variables that affect the fiber welding process is presented. Cotton cloth samples are treated with controlled amounts of 1-ethyl-3-methylimidazolium acetate for a series of times and temperatures. Diluting the ionic liquid with a volatile molecular co-solvent allows temporal and spatial control of the welding process not possible with neat ionic liquids. Materials are characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, and mechanical (tensile) testing. Results suggest careful management of process variables permits controlled, reproducible manipulation of chemical and physical properties.

高出力・高輝度レーザによる高張力鋼厚板のホットワイヤ併用突合せ溶接法

High-power and high-brightness lasers such as fiber laser or disk laser are promising as desirable heat sources for deeply-penetrated welds, owing to their superior power density. However, their tightly-focused beam spots have low gap tolerance in butt welding. The objectives of this research are to investigate penetration characteristics, to clarify welding phenomena and to develop high quality welding procedures in butt welding with several gaps of zero to 0.4 mm for 590 MPa-high-strength steel plates with a 10 kW fiber laser or a 16 kW disk laser. The butt welding was performed on 12 mm-thick plates under several welding conditions including using a cold wire or a hot wire. In the case of 0.4 mm gap, underfilling and burn-through welds were obtained by the conventional 10 kW fiber welding and with using a cold wire. On the other hand, welding defects were greatly reduced with a hot wire. Moreover, a 16 kW high power disk laser with a hot wire could produce sound fully-penetrated welds to suppress not only the welding defects but also oxygen content in the weld fusion zone. The weld penetrations were stable in spite of several gaps from zero to 0.4 mm, owing to removal of excessive melt depending on the gap size from bottom keyhole inlet in the molten pool by a strong laser-induced plume.Consequently, it was revealed that laser power sufficient to produce a full-penetrated keyhole using a hot wire was effective to the improvement of gap tolerance and suppression of oxygen content in the weld fusion zone in butt welding of thick high-strength steel plates with a high-power and high-brightness laser.

Characterization of Polymer Movement in Fiber Welded Cellulose Composites

Several examples of fiber welding were characterized by visible, fluorescent, and scanning electron microscopies to evaluate polymer reorganization. Distinct morphologies were observed that are process dependent. The characterization of process controlled sample morphology is the basis for understanding observed bulk physical properties such as tensile strength and the modulus.

Process Variables that Control Natural Fiber Welding

Preliminary data are shown for a systematic study of the variables that control the fiber welding process. Cotton cloth samples are treated with various amounts of 1-ethyl-3-methylimidazolium acetate for a series of times and temperatures. Processed materials are characterized by scanning electron microscopy, infrared spectroscopy, x-ray diffraction, and mechanical (tensile) testing. Chemical and physical properties are shown to be controllably modified with careful management of process variables.

Mode coupling of microstructured optical fibers using temperature-dependent nitrogen-doped silica fibers

A promising method for the diminishing of loss upon the welding of microstructured optical fibers with suspended core is proposed. The method is based on the application of the nitrogen-doped optical fiber whose thermally expanding core serves as the mode coupler. The loss related to the welding of the conventional fiber (Corning SMF-28 and OFS Clearlite 980) and the suspended-core microstructured fiber (with a core diameter of about 2 μm at wavelengths of 1060, 1310, and 1550 nm) using a conventional welding device is experimentally studied. The welding loss (less than 0.5 dB) in a wide spectral range is several times less than the loss corresponding to the existing methods for the coupling of conventional and microstructures fibers.

Process Variables that Control Natural Fiber Welding

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Natural Fiber Welding

AbstractA process we term “natural fiber welding” is demonstrated by which loose fibers are transformed to create a congealed network using an IL solvent. Several examples are discussed that include cellulosic and protein‐based materials. SEM shows the fusion of fibers upon treatment. XRD and FT‐IR spectroscopy of cellulosic materials show that significant amounts of the native polymer structure are retained after the process is completed. Data suggest that material at the fiber exterior is preferentially transformed while material in the fiber core is left in the native state. Data also demonstrate that the amount of material modified can be tailored by control of variables such as the IL solvent concentration, the process temperature, and the processing time.magnified image

Light-Induced Self-Writing Welding of Optical Fiber

We developed a process based on the self-focusing principle for the fabrication of a photopolymer junction between two optical fibers ends. Photopolymerization is initiated by a green laser light injected in both fibers, whereas a red inactinic beam monitors the coupling ratio between the fibers. This setup is well adapted to the real-time analysis of the junction formation and may be seen as a new tool of investigation of the formation of the self-writing photopolymer elements.

FEM Investigation of the Temperature Field of Energy Director During Ultrasonic Welding of PEEK Composites

In this study, a finite element model of ultrasonic welding of continuous carbon fiber (CF) reinforced polyetheretherketone (PEEK) laminates is established based on the viscoelastic dissipation theory. The impacts of the size and apex angle of the energy director on the heating process during ultrasonic welding are discussed. Simulation results show that the apex angle of the energy director has a more significant effect on the temperature rising rate than size of the energy director. The apex angle also greatly affects the temperature field profile of the energy director. The highest temperature region of energy directors with 30 and 60° apex angle presents a butterfly shape and deviates a distance from the lower laminate. The ‘wings’ of the highest temperature region of the 90° energy director nearly merge together and make contact with the lower laminate. The highest temperature region of 120° energy director becomes a closed ellipse area but is wrapped in the energy director tip. As the cross-sectional area of the energy director is smaller than 0.25 mm2, the heated region on the energy director and lower laminate decreases with the cross-sectional area. As the cross-sectional area exceeds 0.25 mm2, the heated area on the energy director and lower laminate remains constant. Therefore, an energy director with a 90° apex angle and about 0.25 mm2cross-sectional area may be the most suitable for ultrasonic welding of CF/PEEK laminates.

Laser transmission welding of polymer and wood composites: Material and joint mechanism related studies

Laser beam transmission welding is an innovative and promising technology for many industries such as the automotive, electronic, and medical industry. Extension to application of this technology to wood components makes it also interesting for the woodworking and furniture industry. Therefore, several investigations in the field of welding of fiber reinforced thermoplastic and wood composites with polymers have been carried out. Focus is given to the determination of the weldability and weld behavior of different thermoplastic and wooden materials in matrices relevant for recent industrial applications. Different laser sources with a variety of wavelengths are examined, e.g., high power diode lasers (810, 940 nm) and Nd Yttritium–aluminum–garnet (YAG) laser systems (1064 nm). New approaches using thermographic methods for an easy and fast evaluation of materials qualification regarding their weldability will also be presented. Different plastic and wood components taking into account properties like filling content are investigated. Results show that the thermographic transmission and heating rate are more or less different for Nd:YAG and diode laser radiation depending on the type of laser-transparent polymer material, production conditions, and on the presence of pigments and other filling materials. Investigating the absorbing materials, it has been shown clearly that a modification of the carbon content is observable very easily in the thermographic images recorded during the heating period. Since natural fiber composites have strong material inhomogenities and anisotropic structures, special process strategies for their application have been developed and are presented in this article.

Resistance Welding of Carbon Fiber Reinforced Polyetherimide Composit

CF/PEI laminates were joined using a resistance welding (fusion bonding) technique. The heating element has a sandwich structure consisting of two GF/PEI prepregs covering both sides of a stainless metal mesh. The mechanical properties of a flat welded panel were characterized by three-point bending, Mode II ENF interlaminar fracture, instrumented Charpy impact, and falling weight impact tests. Failure occurred mainly inside the adherent laminates adjacent to the heating element in the areas with deconsolidation that occurred during joining. The defect size and intensity could be minimized by increasing the hold pressure. The delamination area decreased with increasing hold pressure at the same impact energy level.