J.K. Beddow

On the Hausner Ratio and its relationship to some properties of metal powders

Abstract The ratio between the tap density and apparent density of a powder mass is termed the Hausner Ratio. Values of this ratio, flow times and angles of repose are compared for three types of dry powder and for two types of oiled copper powder. The results indicate that the Hausner Ratio measures the friction condition in a moving powder mass. It is concluded that the Hausner Ratio is a characteristic of a powder in addition to angle of repose and flow time. Knowledge of the Hausner Ratio is of use in gaining a basic understanding of the mechanism in sieving and of the initial stage of compaction of powders.

Morphological fourier descriptors

Abstract The Fourier method of particle profile representation is presented and discussed. Rotationally invariant size and shape terms are derived from the Fourier particle profile representation. The shape terms are demonstrated to be rotationally invariant as well as magnification (size) invariant. The size and shape terms proposed are shown to include all the available information about the boundary of a particle profile. Mathematical and statistical interpretations of the size and shape terms proposed are demonstrated. Some actual and potential applications are discussed.

A simple relationship between particle shape effects and density, flow rate and Hausner Ratio

Abstract A study has been made of the relative magnitudes of particle shape effects on three bulk solids properties. The bulk solids used in this study were small plastic pellets of regular shapes and sizes. Experimental results indicate that variations in particle normal and tangential not-roundness have marked effects on the apparent density, flow rate and Hausner Ratio of the bulk solids. The not-roundness is the standard deviation of the radial distribution of the particle profile. It is a particle shape characteristic derived from morphological analysis. A simple relation of the form P(bulk property) = P(ideal) + P(deviation) is proposed and tested, in which P indicates the property under test. P(ideal) indicates the value of the property for perfect spheres; P(deviation accounts for the effect of particle shape.

On relating some particle profile characteristics to the profile fourier coefficients

Abstract This paper describes a preliminary investigation of the problems inherent in the development of an interface between a particle shape pre-processor and a binary computer. In the experiment described, the set of data points of the particle profiles are converted into sets of Fourier coefficients, which in turn are converted to features that appear to be capable of human operator assessment. Real particle profiles are analyzed to yield features which are tested for clustering tendencies in the pattern space. Advantages and disadvantages of the method are discussed.

A refined method of particle shape representation

Abstract A new method using parametric Fourier descriptors to represent particle shape is discussed. This method is compared with the ( R , θ) method described elsewhere [1]. The problem of profile re-entrance inherent in the ( R , θ) method is solved completely.

Adhesion and removal of particulate contaminants in a high-decibel acoustic field

Abstract An experimental investigation was conducted to study the interaction of a high-decibel acoustic field with micron-sized particulate matter adhered to a glass slide. The experimental design utilized an acoustic field in order to overcome adhesion forces acting on the contaminant materials. An image analysis technique determined foreign particle counts before and after the cleansing process. Removal efficiencies were calculated for Sound Pressure Levels (SPLs) between 155 and 165 dB. For the materials tested, removal rates were unpredictable and generally poor at SPL

Morphological analysis of metallic wear debris

Abstract A new method of fingerprinting metallic wear debris is described and applied to specific examples of products from wear processes. The potential of the method as a diagnostic tool in engine wear study is discussed.

A shape-modified size correction for terminal settling velocity in the intermediate region

Abstract The terminal velocity of arbitrarily shaped sand particles was experimentally studied in the intermediate (or transition) Reynolds number region (2

A generalized method of morphological analysis (the (R,S) method)

Abstract Two methods to describe particle shape using a truncated Fourier series to represent the particle profile are presented. These are the (R,θ) and the (φ,l) methods. The advantages and disadvantages of each method are discussed and a new third method, called the (R,S) method, is proposed. The (R,S) method is shown to include advantages not common to the (R,θ) and the (φ,l) methods. The (R,S) method may have physical applications most pronounced in dendritic problems. Analogous size and shape terms [4] in the (R,S) method are presented. The mathematical and statistical interpretations of the size and shape terms are presented and analoged with those proposed [4] in the (R,θ) method. The disadvantages of the (R,S) method are discussed.

MORPHOLOGICAL ANALYSIS, TEN YEARS OF PROGRESS

ABSTRACT The need for and the principles of morphological analysis as applied to particulate matter are briefly discussed. Applications of morphological analysis to a number of problems are cited. Topics include: relating morphology to the mechanisms of powder production; wear debris analysis by morphological analysis; and kinetic modeling of crystallization processes. Relationships between the behavior of particulate materials and the morphology of the particles are discussed in connection with: abrasive wear of metals; sedimentation In low flow regimes; measuring of bulk properties including internal angle of friction and flow times; dry separation technology; and scrap recovery techniques. The adaptation of the particle image analyzing system to analyze color as a morphic feature is presented. A number of examples of mixture analysis - classification studies are detailed and finally future work in packed and fluidized beds and slurry transportation is outlined.