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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Mode Transition in Conventional Step-Index Optical Fibers
摘要： The discrete self-imaging effect reveals the distinct properties of cladding modes with core modes in step-index optical fibers, as was shown in our previous work [1], where only the linearly polarized LP0n modes were studied. In this paper, the dispersion diagram of the first 17 vector modes (TE0n, TM0n, HEmn and EHmn) and the related first 9 LPmn modes are calculated by both the full-vector finite element method and the graphical method with a three-layer step-index optical fiber model. The cladding modes distributions and the transitions between the core and cladding modes are analyzed. The results of this work are intended to enrich the knowledge and understanding of modal characteristics of conventional step-index optical fibers.
关键词： Optical fiber dispersion,mode transition,optical fiber cladding,step-index optical fiber,Talbot and self-imaging effect
更新于2025-09-16 10:30:52
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Laser Cladding of Heat-Resistant Iron Based Alloy
摘要： The paper presents the results of the composition, structure and mechanical characteristics of heat-resistant iron based alloy samples produced by laser cladding. The samples were manufactured using secondary raw material (chips), which were converted into powder by plasma spheroidization. The crystalline transformations for the as-processed as well as after several heat treatment conditions were analyzed. Phase, chemical composition and mechanical characteristics were investigated.
关键词： mechanical properties,additive manufacturing,heat-resistant iron based alloy,microstructure,laser cladding
更新于2025-09-16 10:30:52
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Hybrid forming mechanism of patternless casting and laser cladding
摘要： In accordance with the requirement of manufacturing dies quickly and economically, a hybrid forming method of stamping dies for automobile panels is proposed. The method combines digital patternless casting and high-power laser cladding. An experimental study is conducted on the hybrid forming process and its trial production and application in the manufacturing of stamping dies for typical panels. Results prove that the laser cladding layer exceeds HRC60 (Rockwell hardness) and thus meets the production efficiency requirement of automobile dies. The rate of defects is well controlled. Compared with traditional technology, this technology has remarkable advantages and advancement.
关键词： forming,rapid tooling,laser cladding,patternless casting,hybrid
更新于2025-09-16 10:30:52
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Research on Microstructure and Hardness of Laser Cladding Using the Mixed Powder of Nano-TiC and Ni-Based Alloy
摘要： Aiming at the problem of poor high-temperature wear-resistance of rope clamp used in super-high speed elevators, the experiments of laser cladding to prepare carbide reinforced composite coating were made. Nano-TiC powder, Ni-based alloy powder were used as cladding material. The microstructure and hardness of composite coating were tested by relevant equipments. The research results show that the composite coating is made up of TiC, Cr3C2, Fe3C and Fe-Ni-Cr-C solid solution. When the content of TiC is 10%, 30%, the morphology of TiC is presented as dendrite-like and the morphology of solid solution is presented as cellular-like. When the content of TiC is 50%, the morphology of TiC is presented as block-like, lath-like. There are some microcracks on grain boundaries. At the content of 30%, laser power 1.5KW, scanning speed 600mm/min, the laser cladding has no crack and hole. The average hardness of composite coating is 701HV0.2. Using this technology to the surface strengthening of elevator parts, the wear resistance and service life can be greatly improved.
关键词： nano-TiC,laser cladding,hardness,composite material,microstructure
更新于2025-09-16 10:30:52
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Fiber grating sensing interrogation system based on a modulated grating Y-branch tunable laser for core-and-cladding-integrated fiber Bragg grating temperature measurement
摘要： Numerous studies have addressed various methods to interrogate fiber Bragg gratings (FBGs). However, conventional methods are ineffective for multipeak FBG demodulation. A core-and-cladding-integrated fiber Bragg grating (FBG) temperature-interrogation system, based on a modulated grating Y-branch (MG-Y) tunable laser and home-built FBG, is proposed in this study. The sensing system comprises an MG-Y tunable laser interrogation system, a 3-dB optical fiber coupler, a core-and-cladding-integrated FBG, a heating platform, and a personal computer. The core-and-cladding-integrated FBG with two reflection peaks is sampled by the designed MG-Y laser. The FBG has a period of 534 nm and a grating length of 2000 μm. It is fabricated in a single-mode fiber by femtosecond-laser writing through the fiber coating. The interrogator is suitable for temperature measurement via the core-and-cladding-integrated FBG. In tests of the temperature-interrogation system, a temperature change from 30 to 100 ○C generates spectral shifts toward longer wavelengths for both the core and cladding reflection peaks. For the core and cladding, temperature sensing sensitivities of 111 and 113 pm/○C with linearities of 0.993 and 0.99, respectively, during heating and 117 and 120 pm/○C with linearity coefficients of 0.994 and 0.99, respectively, during cooling are achieved.
关键词： fiber Bragg grating,femtosecond-laser writing,modulated grating Y-branch tunable laser,temperature measurement,core-and-cladding-integrated FBG
更新于2025-09-16 10:30:52
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A convolutional approach to quality monitoring for laser manufacturing
摘要： The extraction of meaningful features from the monitoring of laser processes is the foundation of new non-destructive quality inspection methods for the manufactured pieces, which has been and remains a growing interest in industry. We present ConvLBM, a novel approach to monitor Laser Based Manufacturing processes in real-time. ConvLBM uses a Convolutional Neural Network model to extract features and quality indicators from raw Medium Wavelength Infrared coaxial images. We demonstrate the ability of ConvLBM to represent process dynamics, and predict quality indicators in two scenarios: dilution estimation in Laser Metal Deposition, and location of defects in laser welding processes. Obtained results represent a breakthrough in the 3D printing of large metal parts, and in the quality control of welding processes. We are also releasing the ?rst large dataset of annotated images of laser manufacturing.
关键词： Quality-control,Laser-cladding,Laser-welding,Convolutional-neural-networks,Neural-networks
更新于2025-09-16 10:30:52
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Enhanced wear resistance and new insight into microstructure evolution of in-situ (Ti,Nb)C reinforced 316??L stainless steel matrix prepared via laser cladding
摘要： An MC (M: Ti,Nb) carbide-reinforced 316 L coating was synthesized in-situ via laser cladding. A strong relationship between the (Ti,Nb)C content and the microstructure and tribological properties of the resulting components was established. This relationship helped explain the in?uence of the (Ti,Nb)C content on the phase evolution, microstructure characteristics, and exothermic reaction behavior. It was found that the size and morphology of in-situ generated (Ti,Nb)C particles changed as the carbide content increased. When the MC carbide content increased from 2.5 wt% to 10 wt%, the morphology of in-situ generated (Ti,Nb)C evolved from irregular geometry particles, to spherical particles, and ?nally into near-regular geometry. When the carbide content reached 15 wt%, the (Ti,Nb)C particles displayed an equilibrium octahedral structure. The calculated formation enthalpy of MC carbides showed that the reaction enthalpy increased with the MC carbide content, which a?ected the dynamic temperature of the molten pool and eventually led to carbides with di?erent crystal morphologies and sizes. Room-temperature dry sliding friction and wear tests showed that the submicron (Ti,Nb)C carbide reinforced (carbide content: 5 wt%) coating and 1.5 ??m regular octahedral particle-reinforced coating (carbide content: 20 wt%) exhibited a lower friction coe?cient and wear volume loss. Understanding the morphological evolution mechanism of (Ti,Nb)C and its corresponding tribological behavior will enable the development of guidelines to obtain (Ti,Nb)C/316 L metal matrix composite coatings produced by laser cladding.
关键词： (Ti,Nb)C,Laser cladding,Tribological behavior,Microstructure,In-situ
更新于2025-09-16 10:30:52
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Investigation of Geometric Characteristics in Curved Surface Laser Cladding with Curve Path
摘要： Laser cladding on curved surfaces is essential in industrial applications for restoration and remanufacturing of high-value parts. This study investigated the in?uence of di?erent factors on clad width, clad height, and dilution rate in curved surface laser cladding with curved path. Mathematical models were developed using central composite designs to predict these geometric characteristics by controlling laser power, scanning speed, gas ?ow, and altering the outside radius of the cylindrical substrate. Analysis of variance and response surface methodology indicated that clad width increased with increasing laser power and reducing scanning speed. Clad height positively correlated to laser power and negatively correlated to the outside radius of the cylindrical substrate. Increasing the laser power while decreasing the scanning speed led to an increase in dilution rate. Afterwards, the geometric characteristics of the clad were improved by optimizing these factors with the target to maximize clad width and height as well as to minimize dilution rate. The di?erence between model predictions and experimental validations for clad width, clad height, and dilution rate were 3.485%, 3.863%, and 6.566%, respectively. The predicted accuracy was veri?ed with these models, and they were able to provide theoretical guidance to predict and control the geometric characteristics of curved surface laser cladding with a curved path.
关键词： central composite design,curved surface,forming control,curve path,laser cladding
更新于2025-09-16 10:30:52
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The influence of laser engineered net shaping (LENSa?￠) technological parameters on the laser deposition efficiency and properties of H13 (AISI) steel
摘要： A successful attempt at laser cladding of H13 (AISI) hot work tool steel by the laser engineered net shaping technique is presented. Technological parameters, such as laser spot diameter, powder flow rate, and deposition velocity, were changed during the experiment. The influences of the different technological parameters on the efficiency of the cladding, geometry of the clads and properties of the deposited material were investigated. As a result, 75 different samples were deposited. The efficiency of the cladding varies significantly within the chosen range of parameters and is as low as several percentage points. The chosen parameters also appear to affect the shape of the clad, size of the heat-affected zone, microstructure and hardness of the steel, which ranged from 500 to 800 HV after deposition. The proper choice of parameters led to the desired surface hardness of the deposited material, and a heat treatment of the final product may not be necessary.
关键词： Clads geometry,Direct energy deposition,Deposition efficiency,Laser cladding,Microstructure,H13 tool steel,Microhardness,LENS?
更新于2025-09-16 10:30:52
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A contribution to laser cladding of Ti-6Al-4V titanium alloy
摘要： A wear resistant coating was successfully made on an annealed Ti-6Al-4V titanium alloy by laser surface cladding using 60 wt.% WC + wt.% 40 NiCrBSi powder blends. Coaxial laser cladding was performed by means of Yb:YAG disk laser with a 3-KW continuous wave. Different laser interaction times were attempted to get the optimal conditions for promising mechanical properties. The new contribution was to accomplish larger clad layer thickness with applying the shortest possible laser interaction time that can achieve superior clad layer properties. This will decrease energy consumption with an expected money saving which is an essential factor for successful engineering solutions. A high powder ?ow rate of 20 g.min(cid:1)1 was intended in order to obtain a thick, nonporous and crack free clad layer. The clad samples were subjected to thorough microstructure investigations, in addition to microhardness and wear evaluation. The coating so produced exhibits multiple hardness values and exceptional wear resistance under adhesive/sliding wear conditions. The obtained results expose clad layer with superior quality that was achieved at a laser interaction time of 0.3 s. An enhancement in the microhardness values of the clad layers by more than fourfold was attained and the wear resistance was thus signi?cantly improved.
关键词： coaxial laser cladding process,titanium alloy,laser powder cladding,laser interaction time,microhardness,laser surface treatment,wear resistance
更新于2025-09-12 10:27:22