Impact Wear of Materials

Engel, Peter A.; Ling, F. F.

doi:10.1115/1.3424343

Cited by 97 publications

(74 citation statements)

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“…These processes include cavitation and groundwater sapping, and processes that have been suggested to play a role in bedrock-river erosion but to date lack conclusive field evidence (Whipple et al, 2000;Lamb et al, 2006). Entrainment of cohesive bed sediment from clearwater flows has been studied extensively experimentally (e.g., Dzulynski and Sanders, 1962;Shepherd and Schumm, 1974;Annandale, 1995;Brooks, 2001), but application of these results to bedrock rivers is unclear because rock erosion typically involves brittle fracturing (Engle, 1978). Corrosion, the collective weathering processes that weaken rock fabric and joints, is important in fluvial bedrock erosion, but to date has received little study experimentally A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 8…”

Section: Accepted Manuscriptmentioning

confidence: 96%

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New insights into the mechanics of fluvial bedrock erosion through flume experiments and theory

et al. 2015

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Please cite this article as: Lamb, Michael P., Finnegan, Noah J., Scheingross, Joel S., Sklar, Leonard S., New insights into the mechanics of fluvial bedrock erosion through flume experiments and theory, Geomorphology (2015), AbstractRiver incision into bedrock drives the topographic evolution of mountainous terrain and may link climate, tectonics, and topography over geologic time scales. Despite its importance, the mechanics of bedrock erosion are not well understood because channel form, river hydraulics, sediment transport, and erosion mechanics coevolve over relatively long time scales that prevent direct observations, and because erosive events occur intermittently and are difficult and dangerous to measure. Herein we synthesize how flume experiments using erodible bedrock simulants are filling these knowledge gaps by effectively accelerating the pace of landscape evolution under reduced scale in the laboratory. We also build on this work by providing new theory for rock resistance to abrasion, thresholds for plucking by vertical entrainment, sliding and toppling, and assessing bedrock-analog materials. Bedrock erosion experiments in the last 15 years reveal that the efficiency of rock abrasion scales inversely with the square of rock tensile strength, sediment supply has a dominant control over bed roughness and abrasion rates, suspended sediment is an efficient agent of erosion, and feedbacks with channel form and roughness strongly influence erosion rates. Erodibility comparisons across rock, concrete, ice, and foam indicate that, for a given tensile strength, abrasion rates are insensitive to elasticity.The few experiments that have been conducted on erosion by plucking highlight the importance of block protrusion height above the river bed, and the dominance of block sliding and toppling A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 2 at knickpoints. These observations are consistent with new theory for the threshold Shields stress to initiate plucking, which also suggests that erosion rates in sliding-and topplingdominated rivers are likely transported limited. Major knowledge gaps remain in the processes of erosion via plucking of bedrock blocks where joints are not river-bed parallel; waterfall erosion by toppling and plunge-pool erosion; feedbacks between weathering and physical erosion; erosional bedforms; and morphodynamic feedbacks between channel form and erosion rates. Despite scaling challenges, flume experiments continue to provide much needed tests of existing bedrock-erosion theory, force development of new theory, and yield insight into the mechanics of landscapes.

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Section: Accepted Manuscriptmentioning

confidence: 96%

“…Resistance to impact wear in brittle materials can be related to toughness, the capacity to store energy through elastic strain (Engle, 1978). At the limit of brittle failure, the strain energy per unit volume (β) scales with T  2 divided by Young's modulus of elasticity (Y).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

New insights into the mechanics of fluvial bedrock erosion through flume experiments and theory

et al. 2015

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“…High velocity mercury clusters and droplets for these experiments are produced with the help of a gas jet impactor [13,14] whose average speed is measured to be 50 m/s. The gas jet strikes a rectangular (5 mm Â 5 mm) piece of graphite held a few centimeters above the orifice through which the gas jet emerges.…”

Section: Methodsmentioning

confidence: 99%

Graphite dislocations induced by collision of neutral mercury droplets

Ouseph

2009

Applied Surface Science

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“…At shallow angles, erosion proceeds as cutting wear; at large angles, the erosion is mainly due to deformation wear. Experimental study of the erosion of ductile metals by sharp particle impact shows that volume removal is related to the particle velocity to the power greater than 2 but less than 3 [35,36]. The existing theoretical models, however, are not consistent with the experiment.…”

Section: Existing Theory Of Materials Erosion By Solid Particle Impactmentioning

confidence: 97%

Water Jet Machining

Hocheng

Tsai

Chang

2012

Advanced Analysis of Nontraditional Machining

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Water jet drilling, in spite of its advantages of no tool wear and thermal damage, often creates delamination in composite laminate at bottom. An analytical approach to study the delamination during drilling by water jet piercing is presented. This model predicts an optimal water jet pressure for no delamination as a function of hole depth and material parameters.Moreover, the kerf formation of a ceramic plate cut by an abrasive waterjet is discussed. The mechanism and the effectiveness of material removal are studied. The kerf is slightly tapered with wider entry due to decreased cutting energy with kerf depth. A high-power input per unit length produces a small taper but a wide slot.Abrasive waterjet is adequate for machining of composite materials thanks to minimum thermal or mechanical stresses induced. The feasibility of milling of composite materials by abrasive waterjet is discussed. The basic mechanisms of chip formation, single-pass milling, double-pass milling followed by the repeatable surface generation by multiple-pass milling are studied. High volume removal rates as well as a neat surface are desired. Based on the results of single-pass milling tests, this chapter discusses the double-pass milling considering the effect of lateral feed increments. The study then extends to six-pass milling. The obtained surface roughness from the six-pass milling is expressed as a function of the width-to-depth ratio and the lateral increment. With the knowledge of the volume removal rate and the surface roughness as well as the effects of the major process parameters, one can proceed to design a milling operation by abrasive waterjet.

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Impact Wear of Materials

Cited by 97 publications

References 0 publications

New insights into the mechanics of fluvial bedrock erosion through flume experiments and theory

New insights into the mechanics of fluvial bedrock erosion through flume experiments and theory

Graphite dislocations induced by collision of neutral mercury droplets

Water Jet Machining

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