Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index

Atomization and Sprays

Vibration-based damage detection in wind turbine blades using Phase-based Motion Estimation and motion magnification

In spray painting applications, it is essential to generate a spray gun trajectory such that the entire surface is completely covered and receives an acceptably uniform layer of paint deposition; we call this the “uniform coverage” problem. The uniform coverage problem is challenging because the atomizer emits a non-trivial paint distribution, thus making the relationships between the spray gun trajectory and the deposition uniformity complex. To understand the key issues involved in uniform coverage, we consider surface patches that are geodesically convex and topologically simple as representative of subsets of realistic automotive surfaces. In addition to ensuring uniform paint deposition on the surface, our goal is to also minimize the associated process cycle time and paint waste. Based on the relationships between the spray gun trajectory and the output characteristics (i.e., uniformity, cycle time and paint waste), our approach decomposes the coverage trajectory generation problem into three subpro...

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Uniform Coverage of Automotive Surface Patches

Composite materials parts manufacturing

This paper quantifies the elastic behavior and failure response of discontinuous carbon fiber/ epoxy laminates produced by compression molding of randomly oriented preimpregnated unidirectional tape. Flat plates have been successfully molded using manually prepared prepreg charges, and showed a satisfactory degree of randomization. Complex relationships between reinforcement aspect ratio and tensile, compressive, and flexural moduli and strengths are observed. For this particular material system, failure is a matrix-dominated event, with little or no fiber breakage, and it promotes relatively high variation in the measured properties. The high-volume carbon fiber content, combined with an aerospace-qualified epoxy resin, opens up opportunities for more aircraft parts to be made of composite materials, particularly for stiffness-critical components where discontinuous fibers offer performance similar to the continuous quasi-isotropic value.

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Characterization of Prepreg-Based Discontinuous Carbon Fiber/Epoxy Systems

This paper seeks to quantify the influence of microstructural parameters on the mechanical and physical properties of carbon fibre laminates produced by automated directed fibre preforming. The main objective was to establish whether a correlation exists between local areal density variation and mechanical performance. The parameters studied were fibre length, tow filament count and laminate thickness. A statistical process simulation was developed to predict preform density variation and the results were compared with experimental tensile properties. In general, consistent preforms with low areal density variations exhibit higher mechanical properties. There was a notable reduction in areal density variation and consequently an increase in tensile properties with shorter fibres (75–25 mm) and thicker laminates (1.5–4 mm for a constant volume fraction). The effect of filament count was less clear. Simulations indicated that filament count was the most significant parameter in terms of areal density variation; with low filament counts improving density variation by up to 50% (6 K compared with 24 K). However, no variation in tensile properties was observed because of a secondary filamentisation effect caused by the fibre surface treatment.

Characterisation of random carbon fibre composites from a directed fibre preforming process: Analysis of microstructural parameters

Methods and systems for the manufacture of reinforcing preforms for structural composite products. Minimum contact eyelets reduce friction in the supply system for string reinforcing materials. Also, preforms of various configurations and thicknesses can be produced.

Processing systems for automated manufacture of preforms

Surface manufacturing is widely used in industry. Automatic CAD-guided tool planning has many applications in surface manufacturing, such as spray painting, spray forming, rapid tooling, cleaning and polishing. According to the material quantity requirements, these tasks can be categorized into two groups: the material uniformity problem and coverage problem. A general framework is developed to automatically generate trajectories of a free-form surface for these tasks. A given task is first transformed into one of the groups. Based on the CAD model of a free-form surface, constraints and tool model, a trajectory for a free-form surface is generated. Velocity optimization is discussed to optimize the material quantity. Simulations are performed to verify the developed framework. This framework can also be extended to other applications.

Jeffrey Scott Dahl

Papers

Characterisation of random carbon fibre composites from a directed fibre preforming process: Analysis of microstructural parameters

Processing systems for automated manufacture of preforms

A general framework for automatic CAD-guided tool planning for surface manufacturing

A non-orthogonal material model of woven composites in the preforming process

Modeling and Simulation of Compression Molding Process for Sheet Molding Compound (SMC) of Chopped Carbon Fiber Composites