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Femtosecond Laser Ablation for Mesoscale Specimen Evaluation
摘要： Focused ion beam machining revolutionized the way samples are studied in materials science. The introduction of this tool enabled researchers to break into new frontiers of research. While this method focused on the nanometer length scale, the mesoscale manufacturing of samples has not seen such advances. It remains a challenge to manufacture sample geometries too large for focused ion beam milling yet too small for conventional machining. Femtosecond laser ablation opens this length scale of sample space and allows the fabrication of numerous useful geometries. This paper outlines a state-of-the-art femtosecond laser machining system that can be used for rapid, micro- and mesoscale sample preparation. To illustrate the utility of this system, stress–strain data are presented for single-crystal Cu micropillars and three microscale tensile test specimens prepared from physical-vapor-deposited Cu and Ni foils.
关键词： Femtosecond laser ablation,mesoscale specimen,microstructure examination,mechanical testing
更新于2025-09-19 17:13:59
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Laser Welding of Transmitting High-Performance Engineering Thermoplastics
摘要： Laser processing is a rapidly growing key technology driven by several advantages such as cost and performance. Laser welding presents numerous advantages in comparison with other welding technologies, providing high reliability and cost-effective solutions. Significant interest in this technology, combined with the increasing demand for high-strength lightweight structures has led to an increasing interest in joining high-performance engineering thermoplastics by employing laser technologies. Laser transmission welding is the base method usually employed to successfully join two polymers, a transmitting one through which the laser penetrates, and another one responsible for absorbing the laser radiation, resulting in heat and melting of the two components. In this work, the weldability of solely transmitting high-performance engineering thermoplastic is analyzed. ERTALON 6 SA, in its white version, is welded by a pulsed Nd:YAG laser. Tensile tests were performed in order to evaluate the quality of each joint by assessing its strength. A numerical model of the joint is also developed to support the theoretical approaches employed to justify the experimental observations.
关键词： pulsed Nd:YAG laser welding,numerical model,polyamide 6,ERTALON 6 SA,high-performance engineering thermoplastic,mechanical testing
更新于2025-09-19 17:13:59
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Laser Weldability of AlSi10Mg Alloy Produced by Selective Laser Melting: Microstructure and Mechanical Behavior
摘要： Selective laser melting (SLM) allows 3D complex parts to be produced with integrated functionalities but does not permit to realize large dimension parts, as the building chamber volume of commercial SLM systems is limited. Therefore, the possibility of joining SLM-built parts by welding appears as extremely valuable. In this work, laser weldability of SLMed AlSi10Mg parts has been investigated. The cooling rates induced by the welding process are lower than the ones of SLM; therefore, typical eutectic silicon network of SLM-built parts appears broken in both the melted zone and part of the heat-affected zone, as con?rmed by calorimetric measurement. This microstructural evolution caused a local decrease of hardness from 132 HV to 73 HV and a reduction of ductility caused by porosity formation in the weld bead. Moreover, the thermal treatment, performed at 320°C, can limit the gap of tensile response among welded bead and base SLM material.
关键词： laser welding,selective laser melting,mechanical testing,microstructure,AlSi10Mg
更新于2025-09-11 14:15:04
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On-the-Fly Fast X-Ray Tomography Using a CdTe Pixelated Detector – Application in Mechanical Testing
摘要： Fast tomography measurements are still done almost exclusively within the domain of synchrotrons. However, recent progress in X-ray imaging instrumentation has enabled researchers to perform time-lapse computed tomography (4D-CT) even under laboratory conditions with standard X-Ray sources. Thus, fast time-dependent processes within materials with relatively high X-Ray attenuation can be monitored. The article describes the in-situ tomographic monitoring of crack formation and propagation in a quasi-brittle silicate matrix composite subjected to three point bending. A three-dimensional CT volume containing the region of interest (ROI) in the specimen is imaged over a period of time while the continuously increasing load causes crack initiation and propagation, creating a dynamic volume dataset. An acquisition time of 50 seconds for one full angle tomography with 400 projections makes this tomographic system one of the fastest systems in the world. The resulting visualizations provide qualitative information concerning progressive crack propagation within areas of lower material density. Differential images then allow displaying the spatial orientation of the crack over time. The results were further processed for a quantitative analysis of image quality using various methods of beam hardening correction.
关键词： X-ray imaging techniques,X-ray tomography,Materials characterization,Mechanical testing,Quasi-brittle material,Fracture mechanics,CdTe detectors
更新于2025-09-10 09:29:36
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Nonparasitic behavior of embedded triboluminescent sensor in multifunctional composites
摘要： Bio-inspired In situ Triboluminescent Optical Fiber (ITOF) sensors are embedded into the composites for real-time distributed damage monitoring. Real-time damage sensing in large composite structures is imperative to allow for necessary actions before catastrophic failure occurs. This article investigates how embedded ITOF sensors affect the tensile and flexural properties of composite laminates. ITOF sensors with diameters of 275, 570, and 1500 μm, were embedded into the carbon fibers/vinyl ester composite laminates. The ultimate tensile strength and the shear strength of composites with embedded 275 μm reduce by about 0.15% and 1.41%, respectively when embedded in 0° direction. Small-sized sensors have a moderate adverse effect on tensile properties of composite, particularly in the direction perpendicular to the ITOF sensor. Additionally, the ability of the varying ITOF sensors to monitor the low velocity impact damage in composites was assessed. Small-sized sensors demonstrate nonparasitic behavior in multifunctional composites when embedded in 0° direction.
关键词： A. Multifunctional composites,E. Vacuum infusion,B. Mechanical properties,D. Mechanical testing
更新于2025-09-04 15:30:14