Three-Dimensional Laser Machining of Composite Materials

This paper presents a concept for performing three-dimensional laser machining on composite materials, using two intersecting laser beams to create grooves on a workpiece. A volume of material is removed when the two grooves converge. An analysis of the grooving process was conducted for carbon/teflon and glass/polyester materials. A model was developed to determine groove depth from process parameters and material properties. Close agreement was found between model predictions and experimental results for groove depths in carbon/teflon. Model predictions consistently overestimated depth values for continuous-beam glass/polyester results, and underestimated depth values for pulsed-beam glass/polyester at low power/high speed. Corrections for heat losses and high-temperature chemical interactions were added to the model to improve agreement with data. Groove width and damage width results were compared with surface quality standards for laser cutting of composites.

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The 2D-S (Stereo) Probe: Design and Preliminary Tests of a New Airborne, High-Speed, High-Resolution Particle Imaging Probe

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech1927.1 ◽

2006 ◽

Vol 23 (11) ◽

pp. 1462-1477 ◽

Cited By ~ 205

Author(s):

R. Paul Lawson ◽

Darren O’Connor ◽

Patrick Zmarzly ◽

Kim Weaver ◽

Brad Baker ◽

...

Keyword(s):

High Speed ◽

Three Dimensional ◽

Sample Volume ◽

Laser Beams ◽

Probe Design ◽

Test Bed ◽

Pixel Resolution ◽

Small Water ◽

Particle Imaging ◽

Overlap Region

Abstract The design, laboratory calibrations, and flight tests of a new optical imaging instrument, the two-dimensional stereo (2D-S) probe, are presented. Two orthogonal laser beams cross in the middle of the sample volume. Custom, high-speed, 128-photodiode linear arrays and electronics produce shadowgraph images with true 10-μm pixel resolution at aircraft speeds up to 250 m s−1. An overlap region is defined by the two laser beams, improving the sample volume boundaries and sizing of small (<∼100 μm) particles, compared to conventional optical array probes. The stereo views of particles in the overlap region can also improve determination of three-dimensional properties of some particles. Data collected by three research aircraft are examined and discussed. The 2D-S sees fine details of ice crystals and small water drops coexisting in mixed-phase cloud. Measurements in warm cumuli collected by the NCAR C-130 during the Rain in Cumulus over the Ocean (RICO) project provide a test bed to compare the 2D-S with 2D cloud (2D-C) and 260X probes. The 2D-S sees thousands of cloud drops <∼150 μm when the 2D-C and 260X probes see few or none. The data suggest that particle images and size distributions ranging from 25 to ∼150 μm and collected at airspeeds >100 m s−1 by the 2D-C and 260X probes are probably (erroneously) generated from out-of-focus particles. Development of the 2D-S is in its infancy, and much work needs to be done to quantify its performance and generate software to analyze data.

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Thermo-Mechanical Modelling of Jointing Process by Friction Stir Welding of Aluminium-Based Composite Materials

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.188.144 ◽

2012 ◽

Vol 188 ◽

pp. 144-149

Author(s):

Marius Pop-Calimanu ◽

Traian Fleșer

Keyword(s):

Composite Materials ◽

Friction Stir Welding ◽

High Speed ◽

Active Element ◽

Three Dimensional ◽

Maximum Temperature ◽

Friction Stir ◽

Thermal Fields ◽

Welding Defects ◽

Dimensional Distribution

Jointing with rotary active element gains field through technological facilities offered nowadays. Own research have developed a model for studying the thermal fields and the plastic deformations of jointing composite materials Al/20%SiC combined by friction stir welding (FSW). In this article we will present the three-dimensional distribution of investigated fields, correlated with input parameters in the process. The process is performed with solid state components. The numerical results indicate that the maximum temperature in the FSW process increases with increasing speed of rotational tools. For high speed welding joint, should be increased, at the same time, the rotational speed to avoid welding defects.

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Dynamic Response of Orthogonal Three-Dimensional Woven Carbon Composite Beams Under Soft Impact

Journal of Applied Mechanics ◽

10.1115/1.4031455 ◽

2015 ◽

Vol 82 (12) ◽

Cited By ~ 14

Author(s):

P. Turner ◽

T. Liu ◽

X. Zeng

Keyword(s):

Finite Element ◽

Composite Materials ◽

Dynamic Response ◽

Finite Element Modeling ◽

High Speed ◽

Three Dimensional ◽

Composite Beams ◽

High Speed Photography ◽

Element Modeling ◽

Back Face

This paper presents an experimental and numerical investigation into the dynamic response of three-dimensional (3D) orthogonal woven carbon composites undergoing soft impact. Composite beams of two different fiber architectures, varying only by the density of through-thickness reinforcement, were centrally impacted by metallic foam projectiles. Using high-speed photography, the center-point back-face deflection was measured as a function of projectile impulse. Qualitative comparisons are made with a similar unidirectional (UD) laminate material. No visible delamination occurred in orthogonal 3D woven samples, and beam failure was caused by tensile fiber fracture at the gripped ends. This contrasts with UD carbon-fiber laminates, which exhibit a combination of widespread delamination and tensile fracture. Post impact clamped–clamped beam bending tests were undertaken across the range of impact velocities tested to investigate any internal damage within the material. Increasing impact velocity caused a reduction of beam stiffness: this phenomenon was more pronounced in composites with a higher density of through-thickness reinforcement. A three-dimensional finite-element modeling strategy is presented and validated, showing excellent agreement with the experiment in terms of back-face deflection and damage mechanisms. The numerical analyses confirm negligible influence from through-thickness reinforcement in regard to back-face deflection, but show significant reductions in delamination damage propagation. Finite-element modeling was used to demonstrate the significant structural enhancements provided by the through-the-thickness (TTT) weave. The contributions to the field made by this research include the characterization of 3D woven composite materials under high-speed soft impact, and the demonstration of how established finite-element modeling methodologies can be applied to the simulation of orthogonal woven textile composite materials undergoing soft-impact loading.

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Application of laser scanning for monitoring condition of buildings and structures during reconstruction

Transfer of innovative technologies ◽

10.32347/tit2141.0106 ◽

2021 ◽

pp. 33-36

Author(s):

Irina Rudneva

Keyword(s):

High Speed ◽

Laser Scanning ◽

New Technology ◽

Three Dimensional ◽

Return Time ◽

Measurement Methods ◽

Laser Beams ◽

Operational Control ◽

Labor Costs ◽

Engineering Geodesy

Ground-based laser scanning technology has been increasingly used in the last 15 years to solve problems not only in engineering geodesy, but also in the inspection of buildings and structures, in particular to identify damage and deformation during operation and reconstruction, as well as operational control of construction. and monitoring of their condition during operation, 3D-modeling of complex architectural objects. The growing popularity of laser scanning is due to a number of advantages provided by the new technology in comparison with other measurement methods. Among the advantages are the main ones: increasing the speed of work and reducing labor costs. The emergence of new more productive models of scanners, improving software capabilities allows us to hope for further expansion of the scope of ground-based laser scanning. Three-dimensional laser scanning emits millions of laser beams and, by calculating their return time, can accurately and accurately calculate their three-dimensional locations to make multiple high-speed scans combined into one system. This works by digitally recording the dimensions and spatial communication of objects by reflecting laser radiation.

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Servo Design for a 3-D Laser-Tracking Measurement System

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.2801170 ◽

1996 ◽

Vol 118 (3) ◽

pp. 476-481 ◽

Cited By ~ 3

Author(s):

Jia-Yush Yen ◽

Chao-Si Jeng ◽

Kuang-Chau Fan

Keyword(s):

Measurement System ◽

High Speed ◽

Optimization Technique ◽

Three Dimensional ◽

Laser Beams ◽

Measurement Point ◽

Position Measurement ◽

Laser Tracking ◽

Accuracy Measurement ◽

Highly Nonlinear

This paper addresses the servo design for a real-time, laser-tracking, three-dimensional (3-D), position measurement system. The 3-D measurement system uses two sets of tracking mirrors to shine laser beams toward the measurement point. By examining the angles of these mirrors, one can calculate the position of this point. The servo loop in the measurement system corrects the mirror orientations by continuously checking and compensating the offset between the out going laser beam and the beam reflected from a retro-reflector attached to the measurement point. To achieve high speed and high accuracy measurement, the tracking servo system has to compensate for the highly nonlinear nature of the system and maintain the laser beams close to the measurement point. This paper derives the relationship between the tracking angle rotations and the measured beam offsets. By including this relationship in the system model, the linear H∞ optimization technique can be applied for controller synthesis. All the design specifications are then directly implemented.

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High-speed brightfield 3-D imaging and 3-D image analysis of thick and overlapped cell clusters in cytological preparations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168827 ◽

1994 ◽

Vol 52 ◽

pp. 218-219

Author(s):

Robert W. Mackin

Keyword(s):

Image Analysis ◽

High Speed ◽

Three Dimensional ◽

Image Data ◽

Ccd Camera ◽

Objective Lens ◽

Array Processor ◽

Vaginal Smears ◽

Low Contrast ◽

Computer Controlled

This paper presents two advances towards the automated three-dimensional (3-D) analysis of thick and heavily-overlapped regions in cytological preparations such as cervical/vaginal smears. First, a high speed 3-D brightfield microscope has been developed, allowing the acquisition of image data at speeds approaching 30 optical slices per second. Second, algorithms have been developed to detect and segment nuclei in spite of the extremely high image variability and low contrast typical of such regions. The analysis of such regions is inherently a 3-D problem that cannot be solved reliably with conventional 2-D imaging and image analysis methods.High-Speed 3-D imaging of the specimen is accomplished by moving the specimen axially relative to the objective lens of a standard microscope (Zeiss) at a speed of 30 steps per second, where the stepsize is adjustable from 0.2 - 5μm. The specimen is mounted on a computer-controlled, piezoelectric microstage (Burleigh PZS-100, 68/μm displacement). At each step, an optical slice is acquired using a CCD camera (SONY XC-11/71 IP, Dalsa CA-D1-0256, and CA-D2-0512 have been used) connected to a 4-node array processor system based on the Intel i860 chip.

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