- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Laser-assisted in-situ keratomileusis (LASIK) with a mechanical microkeratome compared to LASIK with a femtosecond laser for LASIK in adults with myopia or myopic astigmatism
摘要： Laser-assisted in-situ keratomileusis (LASIK) is a surgical procedure that corrects refractive errors. This technique creates a flap of the outermost parts of the cornea (epithelium, bowman layer, and anterior stroma) to expose the middle part of the cornea (stromal bed) and reshape it with excimer laser using photoablation. The flaps can be created by a mechanical microkeratome or a femtosecond laser.
关键词： mechanical microkeratome,femtosecond laser,myopic astigmatism,LASIK,myopia
更新于2025-09-23 15:21:01
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Flexible OLED display with 620?°C LTPS TFT and touch sensor manufactured by weak bonding method
摘要： By weak bonding method, the first organic light-emitting diode (OLED) display with 620(cid:1)C low-temperature poly-silicon (LTPS) thin film transistor (TFT) and touch sensor, without polyimide (PI) substrate, formed on glass substrates is transferred to non-PI flexible substrates. After transfer, the display image is free from defect, and touch sensor functions normally. Compared with device made on PI substrate, the advantages of device stability and pitch variation by transferring are shown.
关键词： touch sensor,mechanical debonding,OLED,PI-free,weak bonding,LTPS
更新于2025-09-23 15:21:01
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Laser-arc hybrid welding of 12- and 15-mm thick structural steel
摘要： High-power lasers are very effective in welding of plates thicker than 10 mm due to the keyhole mode. High-power intensity generates a vapor-filled cavity which provides substantial penetration depth. Due to the narrow and deep weld geometry, there is susceptibility to high hardness and weld defects. Imperfections occur due to keyhole instability. A 16-kW disk laser was used for single-pass welding of 12- to 15-mm thick plates in a butt joint configuration. Root humping was the main imperfection and persisted within a wide range of process parameters. Added arc source to the laser beam process may cause increased root humping and sagging due to accelerated melt flow. Humping was mitigated by balancing certain arc and other process parameters. It was also found that lower welding speeds (< 1.2 m/min) combined with lower laser beam power (< 13 kW) can be more positive for suppression of humping. Machined edges provided more consistent root quality and integrity compared with plasma cut welded specimens. Higher heat input (> 0.80 kJ/mm) welds provided hardness level below 325 HV. The welded joints had good Charpy toughness at ? 50 °C (> 50 J) and high tensile strength.
关键词： Mechanical properties,Toughness,Thick steel,Hybrid welding,High strength steel,Laser welding
更新于2025-09-23 15:21:01
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Directed energy deposition of Al 5xxx alloy using Laser Engineered Net Shaping (LENS??)
摘要： Here, we present directed energy deposition (DED) of wrought-like Al 5xxx AlMg alloy by Laser Engineered Net Shaping (LENS?). A transition from an Al 5083 gas atomized powder feedstock to Al 5754 characteristics of the as-deposited material due to selective evaporation of Mg was observed. Density values obtained by X-ray micro-computed tomography (μ-CT) were compared to those obtained by the Archimedes method. The latter indicated a relative density as high as 99.26%. Possible origins of porosity are discussed. The as-deposited material was comprised of both equiaxed and columnar grains with no preferred crystallographic orientation and mean grain size of 36 μm. The Young's modulus, yield stress, ultimate tensile strength, fracture strain, Poisson's ratio, and total ultimate strain energy (toughness) were determined by uniaxial tensile tests combined with digital image correlation (DIC). Fractography complemented the mechanical testing. A pulse-echo ultrasonic non-destructive test was used to obtain more accurate values of the Young's and shear moduli and to adjust the value of the yield strength accordingly. The measured mechanical properties meet the requirements of international standards for wrought Al 5754 in its annealed condition.
关键词： Additive manufacturing (AM),Mechanical properties,Micro-computed tomography (μ-CT),Laser Engineered Net Shaping (LENS?),Directed energy deposition (DED),Aluminum alloys
更新于2025-09-23 15:21:01
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Influence of processing parameters on mechanical and fatigue properties of 316??L steel manufactured by selective laser melting
摘要： The Selective Laser Melting process involves multiple factors that are detrimental to fatigue life. It is crucial to select optimal processing parameters to avoid internal porosity, source of early failure through crack initiation mechanisms. Surface condition, especially high roughness values, may also be a critical factor for crack initiation. Influence of surface condition must be studied in the industrial context, where parts may not be completely machined before implementation. This work first focused on finding optimal parameters for producing low-porosity 316 L parts by the SLM process. Once a suitable set of parameters was found, a set of samples was characterized mechanically. Fatigue samples were then produced and submitted to various surface treatments (machining, polishing, …), while some were left as-built. They were then tested in high-cycle fatigue and S-N curves produced for each sample type. This study indicates that high-cycle fatigue life of SLM 316 L is generally inferior to wrought 316 L, with as-built samples exhibiting lower fatigue limits. This was explained by surface roughness acting as crack initiation sites. Porosity was also found to be a very significant factor in fatigue life of SLM 316 L.
关键词： Fatigue,Processing parameters,Selective laser melting,316 L,Mechanical properties
更新于2025-09-23 15:21:01
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Nonlinear Optics || Molecular Origin of the Nonlinear Optical Response
摘要： In Chapter 3, we presented a general quantum-mechanical theory of the nonlinear optical susceptibility. This calculation was based on time-dependent perturbation theory and led to explicit predictions for the complete frequency dependence of the linear and nonlinear optical susceptibilities. Unfortunately, however, these quantum-mechanical expressions are typically far too complicated to be of use for practical calculations. In this chapter we review some of the simpler approaches that have been implemented to develop an understanding of the nonlinear optical characteristics of various materials. Many of these approaches are based on understanding the optical properties at the molecular level. We also present brief descriptions of the nonlinear optical characteristics of conjugated polymers, chiral molecules, and liquid crystals.
关键词： chiral molecules,nonlinear optical susceptibility,liquid crystals,quantum-mechanical theory,conjugated polymers,time-dependent perturbation theory
更新于2025-09-23 15:21:01
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Preliminary Characterization of Glass/Alumina Composite Using Laser Powder Bed Fusion (L-PBF) Additive Manufacturing
摘要： Powder bed fusion (PBF) additive manufacturing (AM) is currently used to produce high-efficiency, high-density, and high-performance products for a variety of applications. However, existing AM methods are applicable only to metal materials and not to high-melting-point ceramics. Here, we develop a composite material for PBF AM by adding Al2O3 to a glass material using laser melting. Al2O3 and a black pigment are added to a synthesized glass frit for improving the composite strength and increased laser-light absorption, respectively. Our sample analysis shows that the glass melts to form a composite when the mixture is laser-irradiated. To improve the sintering density, we heat-treat the sample at 750°C to synthesize a high-density glass frit composite. As per our X-ray diffraction (XRD) analysis to confirm the reactivity of the glass frit and Al2O3, we find that no reactions occur between glass and crystalline Al2O3. Moreover, we obtain a high sample density of ≥95% of the theoretical density. We also evaluate the composite’s mechanical properties as a function of the Al2O3 content. Our approach facilitates the manufacturing of ceramic 3D structures using glass materials through PBF AM and affords the benefits of reduced process cost, improved performance, newer functionalities, and increased value addition.
关键词： density,powder bed fusion,additive manufacturing,mechanical property,3D printing,glass/alumina composite
更新于2025-09-23 15:21:01
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Analysis of the Mechanical Behavior of AISI 4340 Steel Cylindrical Specimens Heat Treated with Fiber Laser
摘要： This paper describes a method for analyzing and improving mechanical behavior of a cylindrical workpiece made of AISI 4340 steel, by its heat treatment with a 3kW fiber laser source. Research and expertise acquired in recent years have shown that improving the mechanical properties of AISI 4340 steel by heat treatment significantly reduces the design dimensions and thus optimizes the final weight of the product. Understanding the impact that a laser heat treatment can have on mechanical properties and the fatigue life can lead to significantly optimizing the design dimensions. This research investigates the effect and control of laser heat treatment parameters to optimize the mechanical behavior of an AISI 4340 steel cylindrical standard-specimen, which has a diameter of the calibrated part of 9.00-mm. The control of the case depth and its uniformization were guided by experimental and numerical modeling. Tensile tests, fatigue tests (hysteresis loops), microhardness, optical microscopy, and scanning electron microscopy measurements were used to evaluate each condition of the experimental design. Results indicate that laser heat treatment increases fatigue endurance by more than 20% compared to non-hardened samples. Moreover, it is shown with a model of neural prediction, and a rigorous analysis of variance, that the numerical values of the mechanical properties are in direct agreement with the laser hardening input parameters.
关键词： Fiber laser,Fatigue endurance,AISI 4340 steel,Mechanical behavior,Heat treatment
更新于2025-09-23 15:21:01
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Flexible Organic Solar Cells Over 15% Efficiency with Polyimide-Integrated Graphene Electrodes
摘要： A highly flexible and durable transparent graphene electrode with thermal stability was developed via the direct integration of polyimide (PI) on graphene. Due to the high transparency of PI-integrated graphene electrode and intimate contact between graphene and PI substrate, high-efficiency flexible organic solar cell with a PCE of 15.2% and outstanding mechanical robustness was obtained.
关键词： Thermal Stability,High Efficiency,Polyimide-Integrated Graphene Electrodes,Flexible Organic Solar Cells,Mechanical Robustness
更新于2025-09-23 15:21:01
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Grain refinement in laser manufactured Al-based composites with TiB2 ceramic
摘要： Al-based composites reinforced with TiB2 ceramics (1 wt.%, 2 wt.% and 5 wt.%) have been manufactured through selective laser melting (SLM). The results show that the densification, microstructure and mechanical properties of the SLM-processed composites are sensitive to the ceramic particle fraction. The average grain size of the composites decreased from ～6.32 μm with increasing TiB2 fraction from 1 to 5 wt.% respectively. Fine equiaxed grains with narrow size distribution were obtained for composites with relatively high amount of TiB2 particles. The effects of TiB2 ceramic fraction on grain refinement and strengthening mechanisms of SLM-processed composites were discussed. Al-based composite with 2 wt.% TiB2 ceramic was determined to be optimum, especially in the view of manufacturing quality, grain refinement and mechanical properties. The composites at an optimum fraction of 2 wt.% TiB2 exhibited high microhardness of ～127 HV0.2, tensile strength of ～444 MPa, yield strength of ～283 MPa and elongation of ～4.2% owing to collective effects of dispersion and grain refinement strengthening as well as high degree of densification. This study can readily offer reference values for laser additive manufacturing of other metal matrix composites to obtain a good compromise of strength and ductility by tuning reinforcement fraction.
关键词： Selective laser melting (SLM),Mechanical property,Al-based composites,Grain refinement,TiB2 ceramic
更新于2025-09-23 15:21:01