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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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    <item>
      <title>THE FRICTION OF QUARTZ IN HIGH VACUUM</title>
      <link>https://trid.trb.org/View/118131</link>
      <description><![CDATA[RESISTANCE TO SHEAR DEFORMATION IN A GRANULAR MASS IS MOBILIZED AT THE POINTS OF CONTACT BETWEEN PARTICLES. A MAJOR PART OF THIS RESISTANCE ARISES FROM INTER-PARTICLE FRICTION. THEREFORE, ANY FUNDAMENTAL STUDY INTO THE MECHANICS OF DEFORMATION OF GRANULAR SYSTEMS REQUIRES AN UNDERSTANDING OF THE NATURE OF SOLID-TO-SOLID FRICTION. DESPITE THIS THERE ARE FEW REPORTS IN THE LITERATURE OF FRICTION MEASUREMENTS ON MINERALS. THE PURPOSE OF THIS INVESTIGATION WAS TO DETERMINE THE FUNDAMENTAL FACTORS CONTROLLING THE FRICTIONAL PROPERTIES OF QUARTZ SURFACES, WITH EMPHASIS ON THE EFFECTS OF SURFACE CLEANLINESS. ULTRA- HIGH VACUUMS AND HIGH TEMPERATURES /TO 350 DEGREES C/ WERE COMBINED WITH CHEMICAL CLEANING AND CAREFUL HANDLING TECHNIQUES TO PRODUCE THE MAXIMUM SURFACE CLEANLINESS. THE COEFFICIENT OF STATIC FRICTION UNDER VARYING ENVIRONMENTAL CONDITIONS WAS MEASURED FOR QUARTZ, 304 STAINLESS STEEL, AND GRANITE. DIRECT SHEAR TESTS WERE RUN ON A QUARTZ SAND /40-60 MESH OTTAWA SAND/ AND ON 30-40 MESH GLASS BALLS. THE COEFFICIENT OF FRICTION OF SMOOTH QUARTZ WAS FOUND TO VARY FROM 0.1 TO 1.0 DEPENDING ON THE SURFACE CLEANLINESS. THE FRICTION OF ROUGH SURFACES SHOWED A MUCH SMALLER VARIATION, WHICH HAS IMPORTANT IMPLICATIONS FOR GRANULAR SOILS. ULTRA- HIGH VACUUM, COMBINED WITH A HIGH TEMPERATURE BAKE-OUT, PRODUCED SIGNIFICANT INCREASES IN BOTH THE ANGLE OF FRICTION OF QUARTZ AND THE PEAK FRICTION OF QUARTZ SAND. THE COHESION INTERCEPT FOR THE QUARTZ SAND ALSO INCREASED BY ABOUT 0.02 KG/CM2. A GOOD CORRELATION, USING THEORETICAL CURVES, WAS OBTAINED BETWEEN CHANGES IN THE ANGLES OF FRICTION FOR QUARTZ. THE HIGH VACUUM-HIGH TEMPERATURE TEST CONDITIONS SIMULATE ASPECTS OF THE LUNAR ENVIRONMENT.  THEREFORE, THE TEST RESULTS MAY YIELD USEFUL INFORMATION REGARDING THE PROPERTIES OF POSTULATED LUNAR SOIL MODELS INVOLVING SIGNIFICANT THICKNESSES OF GRANULAR PARTICLES. /AUTHOR/]]></description>
      <pubDate>Sun, 15 Aug 2004 01:47:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/118131</guid>
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    <item>
      <title>IMPROVING A MATHEMATICAL MODEL OF AN AUTOMOBILE SEAT WITH RESPECT TO SEAT UPHOLSTERY FRICTION</title>
      <link>https://trid.trb.org/View/34375</link>
      <description><![CDATA[This report demonstrates the improvement of the mathematical model of an automobile seat from the aspect of spring characteristics and friction.  The test results were fed into an American computer program on a dummy in a head-on collision in order to show the difference between the American model and the forwarded model.  In all hitherto published reports, the seat friction and spring characteristics of the seat uphostery were observed on an overall constant basis.  In the submitted project, static and sliding friction have been differentiated with respect to seat upholstery friction.  For this reason, the friction coefficient was incorporated into this calculation as a variable over the sliding distance.  Likewise, the spring characteristics of the seat was assumed as a variable over the entire seat upholstery which means for each seat position, that the polynomial coefficients were changed during the collision process to determine the seat upholstery energy.  The spring characteristics and the friction coefficient were ascertained by tests.  These two supplementary procedrues resulted in the kinematics of the dummy, being more closely assimilated to the actual collision process.]]></description>
      <pubDate>Wed, 03 Dec 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/34375</guid>
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      <title>STATIC FRICTION COEFFICIENTS FOR MECHANICAL AND STRUCTURAL JOINTS</title>
      <link>https://trid.trb.org/View/140748</link>
      <description><![CDATA[A review of available data on static friction of steel is presented.  This is directed towards obtaining coefficients of friction applicable to structural connections, particularly those subject to vibratory loading.  The data are found to be inadequate and widely scattered, showing some dependence on normal pressure.  Using a new type of friction apparatus a programme was undertaken to clarify the relationship between static friction coefficient and contact pressure, and also to generate data relevant to mechanical connections.  Results are presented both for machined surfaces and for those commonly encountered in structural work.  Coefficients of static friction for dry mild steel surfaces under nominal contact pressures between 100 and 10,000 P.S.I. are numerically less than those usually quoted in the literature.  Tests were also conducted to measure the coefficient of static friction under dynamic (sinusoidal) in-plane loading.  Results indicate that this may be different from that obtained under purely static loads. This would significantly affect the break-away behaviour of friction connections under vibration.  /Author/]]></description>
      <pubDate>Thu, 27 Feb 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/140748</guid>
    </item>
    <item>
      <title>EFFECTS OF BOUNDARY FRICTION ON TRANSMISSION OF STATIC STRESS THROUGH SAND IN CYLINDRICAL TANKS</title>
      <link>https://trid.trb.org/View/136693</link>
      <description><![CDATA[Experiments to determine the effects of boundary friction on the transmission of static vertical stress through standard 20-30 Ottawa sand in 8-inch I.D. tanks are discussed.  In these experiments the tank type, tank height, applied overpressure, sand density, and boundary treatment were varied.  Theory and derived values for the coefficient of wall friction are included.  Tests showed that the transmission did not vary significantly with overpressure between 1/2 and 6 kg/sq cm (7.11 and 85.32 psi), but decreased as the height of the tank increased. The decrease in transmission with increase in tank height could be approximated by the theoretical equation up to some maximum height.  It is concluded that a greased membrane is perhaps the simplest and certainly an adequate means of reducing wall friction to such levels that no correction in the free-field average vertical stress over small areas in the center of the tank should be required. This could be said of a tank with a height even as great as three times its diameter.  /Author/]]></description>
      <pubDate>Wed, 29 Jan 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/136693</guid>
    </item>
    <item>
      <title>STATIC FRICTION, RELATIONS AMONG SAMPLE DIMENSIONS, AND THE ELASTIC PROPERTIES OF ROCKS /IN RUSSIAN/</title>
      <link>https://trid.trb.org/View/125018</link>
      <description><![CDATA[RESULTS ARE PRESENTED OF LABORATORY INVESTIGATIONS INTO THE INFLUENCE OF (1) THE SLENDERNESS OF PRISMATIC SAMPLES AND (2) THE FRICTION EXERTED BY A COMPRESSION MACHINE AT THE BASE OF THE SAMPLES ON THE MODULUS OF ELASTICITY AND POISSON'S RATIO. /LCPC/RRL/]]></description>
      <pubDate>Mon, 13 Sep 1971 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/125018</guid>
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