Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    UID:
    kobvindex_GFZ20200304155051
    Format: iv, 21 Seiten , Illustrationen
    Series Statement: CRREL Report 79-21
    Content: The report studies the question of whether Great Lakes freighters could move effectively through ice-clogged channels with the aid of tows provided by warping or kedging systems. Ten operational concepts are outlined, and their advantages and disadvantages are noted. The crushing resistance of floating brash ice is then analyzed. The neutral, active and passive states of stress for laterally confined brash ice are considered, and the resistance to horizontal thrusting by a smooth vertical wall is calculated for cohesionless brash ice, and for ice in which there is finite cohesion between the ice fragments. The thickening of the ice cover in the vicinity of a "pusher", and the formation of pressure ridges, are analyzed in order to estimate the amount of pile-up that can occur against a ship hull. The analysis then moves on to consideration of ship resistance by brash ice, taking into account crushing resistance at the bow, tangential friction at the bow, and hull friction aft of the bow section. Comparisons are made between thrust from the ship’s screws and the calculated ice resistance. The next section of the report estimates the force requirements for a warping or kedging system in terms of thrust augmentation for existing vessels. Tow cable requirements are given, and estimates are made for cable anchors and for anchorage of underwater structures. The force and power requirements for winches and windlasses are given, the practical problems involved in the pickup or transfer of cables are mentioned, and the report concludes with a brief appraisal. The conclusion is that a simple warping tug system is appropriate for a full scale experiment, a chain ferry with auxiliary barge seems attractive for an operational system, and a chain ferry plow may be an efficient way to clear ice from channels.
    Note: CONTENTS Abstract Preface Introduction Operational concepts A. Warping tug system B. Chain ferry system C. Chain ferry with auxiliary barge D. Ski tow system E. Dual winch warping system F. Simple kedging G. Trailing-line system H. Above-surface dual winch system I. Pulley systems J. Chain ferry plow Crushing resistance of fragmented ice covers Resistance to ship passage by broken ice Crushing resistance at the bow Tangential friction at the bow Hull friction aft of the bow section Total ship resistance from brash ice Comparison of ship thrust and ice resistance Force requirements for a warping or kedging system Tow cable requirements Anchors and anchorages Force and power requirements for winches and windlasses Pickup or transfer of cable General appraisal Literature cited
    In: CRREL Report, 79-21
    Language: English
    Keywords: Forschungsbericht
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    UID:
    kobvindex_GFZ106417
    Format: xi, 85 Seiten , Illustrationen
    Series Statement: CRREL Report 77-7
    Content: The report deals with the cutting of rock and similar materials by parallel motion tools. It examines cutting forces and energy requirements, taking into consideration tool geometry, wear, operating conditions, and material properties. After an introductory discussion of terminology, some general principles are outlined, and relevant theoretical ideas on metal cutting and rock cutting are reviewed. The next section, which is the heart of the report, reviews experimental data on the magnitudes and directions of cutting forces. There is a graphical compilation of data, including some from obscure or unpublished sources. The variables covered include chipping depth, rake angle, relief angle, side rake, base angle, tool width, tool compliance, tool speed, tool wear, tool interactions, and material properties. The second major part of the report treats the energetics of cutting. It begins with a short discussion of relevant principles, and continues with a compilation and review of experimental data, covering the same independent variables as the force section. The report ends with a concise summary of general behavior for parallel motion tools.
    Note: MAB0014.001: ZSP-201-77/7 , CONTENTS Abstract Preface Foreword Introduction Terminology Principles of cutting Forces acting on a single cutter Theoretical Ideas on cutting Experimental data on cutting forces Effect of chipping depth on tool forces Effect of rake angle on tool forces Effect of relief angle on cutting forces Effect of side rake on tool forces Effect of base angle or face profile on tool forces Effect of rounding at the cutting edge Effect of tool width on cutting forces Tool compliance and force fluctuations Effect of tool speed on cutting forces Effect of rock properties on cutting forces Tool interaction and kerf spacing Effect of multiple pass cutting on tool forces Effect of tool wear on cutting forces Development of wear Energetics of cutting Energetics of parallel-motion tools Variation of specific energy with chipping depth for a single tool Effect of rake angle on specific energy Effect of relief angle on specific energy Effect of side rake on specific energy Effect of base angle or face profile on specific energy Effect of tip radius on specific energy Effect of tool width on specific energy Effect of tool speed on specific energy Variation of specific energy with rock properties Effect of kerf spacing on specific energy Effect of multiple pass cutting on specific energy Effect of tool wear on specific energy General summary Literature cited Appendix Α. Additional data for ice Appendix Β. Conversion factors: U.S. customary and metric units of measurement
    In: CRREL Report, 77-7
    In: Mechanics of cutting and boring, IV
    Language: English
    Keywords: Forschungsbericht
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Book
    Book
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Show associated volumes
    UID:
    kobvindex_GFZ20210210103940
    Format: 38 Seiten , Illustrationen
    Series Statement: CRREL Report 81-17
    Content: Environmental conditions are described for the continental shelf of the western Arctic, and for the shelf of Labrador and Newfoundland. Special emphasis is given to the gouging of bottom sediments by ice pressure ridges and icebergs, and an approach to systematic risk analysis is outlined. Protection os subsea pipelines and cables by trenching and direct embedment is discussed, touching on burial depth, degree of protection, and environmental impact. Conventional land techniques can be adapted for trenching across the beach and through the shallows, but in deeper water special equipment is required. The devices discussed include hydraulic dredges, submarine dredges, plows, rippers, water jets, disc saws and wheel ditchers, ladder trenchers and chain saws, routers and slot millers, ladder dredges, vibratory and percussive machines, and blasting systems. Consideration is given to the relative merits of working with seabed vehicles, or alternatively with direct surface support from vessels or from the sea ice
    Note: CONTENTS Abstract Preface Introduction The western Arctic of North America The continental shelf of Newfoundland and Labrador Burial depth for pipes and cables Degree of protection offered by burial Environmental impact Trenching the beach and the shallows in the western Arctic Trenching beyond the shallows Suction, or hydraulic, dredging Bottom-t raveling cutterhead dredges Plows Rippers Water jets Subsea disc saws and wheel ditchers Subsea ladder trenchers and chain saws Subsea routers and slot millers Bucket ladder trenchers Vibratory and percussive devices Hard rock excavation under water Control and monitoring of subsea machines Vessels and vehicles Trenching from the sea ice Costs of subsea trenching Reference Appendix: Description of waters off Alaska and Newfoundland
    In: CRREL Report, 81-17
    Language: English
    Keywords: Forschungsbericht
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    UID:
    kobvindex_GFZ107371
    Format: ix, 45 Seiten , Illustrationen
    Series Statement: CRREL Report 76-16
    Content: This report, which is one of a series on the mechanics of cutting and boring in rock, deals with the kinematics of machines such as rotary drills, augers, tunnel boring machines, corers, and raise borers, in which the rotary cutting unit revolves about an axis that is parallel to the machine's direction of advance. The discussion and analysis cover the geometry and motion of various components of the cutting systems, including such topics as tool trajectories, tool speeds, motions of the more complicated mechanisms, chipping depth, penetration rates, production and clearance of cuttings, tool angles, and spatial distribution of cutters. Worked examples are given to illustrate the application of various equations to practical problems.
    Note: MAB0014.001: ZSP-201-76/16 , CONTENTS Abstract Preface Summary Foreword Terminology Trajectories of fixed tools Trajectories of roller cutters and indenters Speed of fixed cutting tools Speed of rolling disc cutters Speed and geometry of "wide" roller cutters Skidding rollers "Spiked" rollers Epicyclic or planetary mechanisms Chipping depth and penetration rate Chip production and cutting removal rate Balancing cutting and clearing rates in flight augers Tool relief angles - kinematic considerations Tool rake angles Distribution and spacing of cutting tools Radial tool spacing Angular tool spacing Spacing in the axial direction Literature cited
    In: CRREL Report, 76-16
    In: Mechanics of cutting and boring, (DE-B103)20210225152525
    Language: English
    Keywords: Forschungsbericht
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    UID:
    kobvindex_GFZ20190716152626
    Format: iii, 27 Seiten , Illustrationen
    Series Statement: CRREL Report 85-21
    Content: The development of lightweight coring augers for ice is reviewed. Emphasis is on equipment designed by the Cold Regions Research and Engineering Laboratory and its predecessor organizations for sampling to depths less than 20 m or so. Design and operation of the ACFEL/SIPRE/CRREL 3-in. -ID corer is discussed, and modifications of the basic design for powered operation and for drilling in frozen soil are outlined. Recent replacements for the traditional coring auger are described, and details are given for the construction and operation of the new 4 1/4-in-ID coring equipment. A powered 12-in.-ID drill for shallow-depth coring is also described.
    Note: CONTENTS Abstract Preface Introduction The 3-inch ice corer The Rand auger Parallel development of comparable drills The Big John 12-inch corer Power drives A simple Russian ice-corer Conclusions Literature cited
    In: CRREL Report, 85-21
    Language: English
    Keywords: Forschungsbericht
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    UID:
    kobvindex_GFZ20210323165556
    Format: iv, 38 Seiten , Illustrationen
    Series Statement: CRREL Report 81-26
    Content: Abstract: This report deals with force, torque, energy and power in machines such as drills and boring devices, where the cutting head rotates about a central axis while penetrating parallel to that axis. Starting from a cosideration of the forces developed on individual cutting tools, or segments of cutters, the thrust and torque on a complete cutting head is assessed, and simple relationships between thrust and torque are derived. Similarly, the energy and power needed to drive the cutting head arc estimated and related to tool characteristics. Design characteristics of existing machines are compiled and analyzed to give indications of thrust, torque, power, effective tool forces, nominal thrust pressure, power density, and specific energy.
    Note: CONTENTS Abstract Preface Foreword Introduction Terminology Tool forces Parallel motion tools Indentation tools Head thrust, thrust per unit width, and nominal head pressure Power and power density Torque Specific energy Efficiency and performance index Power requirements for clearance of cuttings Minimum power requirements for lifting cuttings in a vertical hole Power consumption and efficiency in continuous-flight augers Air circulation Mud circulation Literature cited Appendix A: Vertical conveyance by continuous-fiight augers Appendix B: Surface areas on a helical flight and its stem
    In: CRREL Report, 81-26
    In: Mechanics of cutting and boring, Part 7
    Language: English
    Keywords: Forschungsbericht
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    UID:
    kobvindex_GFZ106406
    Format: vii, 36 Seiten , Illustrationen
    Series Statement: CRREL Report 77-19
    Content: Abstract: The report deals with forces and power levels in cutting machines having adisc or drum that rotates about an axis perpendicular to the direction of advance. The forces on individual cutting tools are related to position on the rotor and to characteristics such as tool layout, rotor speed, rotor size, machine advance speed, and rotor torque. Integration leads to expressions for force components acting on the rotor axis, taking into account tool characteristics, cutting depth of the rotor, and rotor torque. These provide estimates of tractive thrust and thrust normal to the primary free surface. For self-propelled machines, this leads to considerations of traction, normal reaction, weight and balance, and power/weight ratios. Specific energy consumption is analyzed and related to machine characteristics and strength ofthe material being cut. Power per unit working area is discussed, and data for existing machines are summarized. Power requirements for ejection ofcuttings are analyzed, and the hydrodynamic resistance on underwater cuttings is treated. A number of worked examples are given to illustrate the principles discussed in the report.
    Note: MAB0014.001: ZSP-201-77/19 , CONTENTS Abstract Preface Foreword Introduction Terminology Forces on individual cutters Torque force and tool force Forces on the rotor axis Tractive thrust and down thrust Alternative tool force formulations Vehicle traction Power/weight ratio Weight and balance Force, torque, speed and power Specific energy Efficiency and performance index Power density Power requirements for ejection of cuttings Hydrodynamic resistance in underwater cutting
    In: CRREL Report, 77-19
    In: Mechanics of cutting and boring, Part VI
    Language: English
    Keywords: Forschungsbericht
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages