US3797303A - Biaxial compression-testing machine - Google Patents

Biaxial compression-testing machine Download PDF

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Publication number
US3797303A
US3797303A US00310094A US3797303DA US3797303A US 3797303 A US3797303 A US 3797303A US 00310094 A US00310094 A US 00310094A US 3797303D A US3797303D A US 3797303DA US 3797303 A US3797303 A US 3797303A
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Prior art keywords
assembly
load
plate
test piece
compression
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Expired - Lifetime
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US00310094A
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English (en)
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J Moulis
A Bascoul
J Bourdes
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Bpifrance Financement SA
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Agence National de Valorisation de la Recherche ANVAR
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/025—Geometry of the test
    • G01N2203/0254—Biaxial, the forces being applied along two normal axes of the specimen

Definitions

  • the machine comprises two compression assemblies, each of which is called upon to apply a monoaxial compression load to the test piece in a direction horizontal and perpendicular to the load applied by the other assembly and coplanar therewith; each assembly includes a jack, the body of which is integral with the frame, and a piston applying pressure to a vertical plate adapted to apply a load to one surface of the test piece; an opposing vertical plate, coaxial with the first plate, is connected to the frame for applying to the opposite parallel surface of the test piece a load of modulus equal to the load applied by the first plate and in opposite direction thereto.
  • each compression assembly is carried, independently of the other assembly, on guide means having little friction and making it possible for the assembly to move freely in a horizontal direction, parallel with the direction of application of the load by the assembly; the guide means associated with the other assembly similarly making it possible for the latter to move in a direction parallel with the direction of application of the load by the other assembly and at right angles to the direction of movement of the first assembly.
  • FIGS 1 BIAXIAL COMPRESSION-TESTING MACHINE The invention relates to a biaxial compression-testing machine making it possible to subject a test piece in the form of a right-angled parallelepiped to a biaxial field of compression stresses.
  • test machines there are many types of test machines in existence which are capable of subjecting a concrete test piece to a biaxial field of compression stresses. These machines may be divided into two categories: one of these categories covers machines, known as flexible machines, consisting of elements capable of undergoing deformation as the test piece is loaded; these machines usually have the advantage of compactness and low cost but they cannot provide accurate measurements, since the deformation suffered by the machines themselves, and the energy of deformation released upon rupture, produce by no means negligeable distortions in the results obtained.
  • flexible machines consisting of elements capable of undergoing deformation as the test piece is loaded
  • these machines usually have the advantage of compactness and low cost but they cannot provide accurate measurements, since the deformation suffered by the machines themselves, and the energy of deformation released upon rupture, produce by no means negligeable distortions in the results obtained.
  • the other category covers machines, known as rigid machines, in which the elements are of a size such that they undergo only minor deformation during loading;
  • the major difficulty faced by the designers of machines of this type is the necessity of applying to the surfaces of the test piece loads which remain accurately centered in all stages of deformation of the test piece since, if meaningful results are to be obtained, it is desirable to avoid introducing any poorly known parasitic stresses, so that only easily measurable biaxial compression stresses are created within the test piece.
  • One of the most advanced machines of this type consists of a fixed frame and a mobile frame suspended within the fixed frame by means of a plurality of rods.
  • the fixed frame is equipped with a jack, the piston of which, integral with a plate, may exert pressure on one surface of the test piece, while an opposing plate, attached to this frame, exerts a pressure in the opposite direction on the opposite surface of the test piece.
  • the mobile frame comprises similar elements arranged at right angles to the first elements and adapted to exert pressure on two other surfaces of the test piece.
  • This type of machine ensures centering of the stresses applied to the surfaces of the test piece as long as the deformation thereof is small, the mobile frame being adapted to follow the deformation of the test piece and thus to centre the directions in which the loads are applied (in relation to the surfaces of the test piece).
  • the restoring forces exerted by the suspension rods depart from the vertical and introduce parasitic stresses which increase as the movement of the mobile frame and the angle between the rods and the vertical increase.
  • the direction of the load applied by the mobile frame is not suitably defined, since this frame, suspended within the fixed frame, may pivot about a vertical axis which produces a poorly known distribution of stresses.
  • Still another purpose of the invention is to provide a machine of simple and compact design, low weight, and relatively low production cost.
  • a biaxial compression machine comprises two compression assemblies, each of which is called upon to apply a monoaxial load to the test piece in a direction known as the loading direction horizontal and perpendicular to the direction of the load applied by the other assembly; each of the assemblies comprises a jack, the body of which is integral with a frame, while the piston thereof applies pressure to a vertical plate adapted to apply a load to one surface of the test piece; an opposing vertical plate, connected to the frame, is arranged coaxially with and opposite to the plate, for the purpose of applying, to the opposite parallel surface of the test piece, a load of modulus equal to the load applied by the first plate and in the opposite direction thereto.
  • each compression assembly is carried, independently of the other assembly, on guided means of displacement, in contact with which the frame of the assembly may move with little friction; these guide means make it possible for the relevant assembly to move freely in a horizontal direction parallel with the direction of application of the load by the said assembly.
  • the guide means associated with the other as sembly make it possible for the latter to move in a direction parallel with the direction of application of the load by this assembly, and therefore at right angles to the direction of movement of the fiirst assembly.
  • FIG. 1a one of the compression assemblies of the machine according to the invention is illustrated schematically in FIG. 1a, in which 1 indicates the frame of the assembly, 2 and 3 indicate the body and piston of the jack fitted to this assembly, 4 indicates the plate associated with p iston 3, and 5 indicates the opposing plate attached to frame 1.
  • the axis of the jack moves from D at velocity v with an acceleration 'y; it is to be understood that the test piece is loaded slowly andprogressively (between 5 and 10 minutes, for example, for a movement of a few tenths of a millimetre), and the value of -y is extremely low.
  • the plate and opposing plate of the second compression assembly exert friction forcesf KF, wherein K is the coefficient of friction between the material of which the plate and opposing plate are made (more particularly steel) and the material of which the test piece is made (concrete).
  • force F producing this movement must be greater than 2KF or than the limit equal to this value.
  • F may therefore be made equal to a-ZKF, wherein a is equal or superior to one.
  • Coefficient of friction K is of the order of 0.2, whereas mass m of the test piece is of the order to 3 kg and never exceeds kg; therefore: p 0.2 F/lO 0.02 F
  • the maximal compression exerted by the compression assemblies is of the order of some tens of tons; it may therefore be assumed that the second compression assembly exerts a compression of more than 1 ton, which corresponds to a force F 10,000 Newtons. This hypothesis may be realized by subjecting the test piece to prior monoaxial compression greater than or equal to this value.
  • Straight line A therefore has the configuration shown in FIG. 1c, and for small values of y (betweenly maxl and ly maxl), which are the only ones corresponding to reality (as already indicated), the value of a is less than one.
  • the weight of a compression assembly adapted to apply a maximal load of 60 tons is of the order of 1.3 tons; the frictional forces are of the order of 5 to 6 kg. It will be seen, therefore, that the ratio of these forces to the load (I e/ 10,000) makes it possible to regard them as completely negligeable.
  • the rails may be placed on three ball-andsocket joints arranged in the form of a triangle, each mounted on a means for adjusting the height of the rails carried on a substantially horizontal base.
  • the frame of each compression assembly consists of rigid horizontal columns arranged in parallel with the loadingdirection of the assembly and connecting together two rigid plates located in close proximity at the ends of the columns, the body of the jack being attached to one of these plates and the opposing plate to the other.
  • each plate is carried on these columns on lowfriction sliding or rolling means, which allow them to move freely along the columns which acts as guides therefor. The movements of this plate are therefore guided completely parallel with the loading direction, and if there is any defect in the alignment of the jack axis, the transverse component of the force applied is absorbed by the columns and is not transmitted to the test piece;
  • each plate is connected, with advantage, to the corresponding columns by means of arms of variable length; these arms, fitted with means of adjusting their lengths, make it possible to centre each of the plates.
  • the elements of one of the compression assemblies are made heavy enough to apply a predetermined maximal load, for example 60 tons, while the elements of the other assembly are made to be able to apply a maximal load half as great, for example, 30 tons.
  • FIG. 2 is a simplified view in perspective designed to facilitate the understanding of the general structure of a machine according to the invention
  • FIG. 3 is a view of the machine from below
  • FIG. 4 is a front elevation of this machine along A-A;
  • FIG. 5 is a section along the line B-B.
  • the biaxial compression testing machine illustrated by way of example, consists of two independent compression assemblies l and 2 with no contact between them.
  • Assembly 1 is designed to be able to apply to the test piece a maximal load of 60 tons along one axis
  • assembly 2 is designed to be able to apply a maximal load of 30 tons along an axis perpendicular to, and coplanar with, the first assembly.
  • Each assembly comprises a rigid frame consisting of four columns 3 connected, in the vicinity of their ends,
  • Each plate 5 is carried by a shoe 6 on a guide rail 7 by means of rollers 8 adapted to roll in slides 9 and 10 having lateral tracks; the fixed slide is attached to rail 7, while the mobile slide is attached to the shoe.
  • Rollers 8 are enclosed in a cage and are arranged at 45 alternately in one direction and the other, in order to provide accurate guidance for shoe 6 in relation to the rail and to apply, under the action of the weight of the relevant compression assembly, substantially balanced lateral loads to slides 9 and 10.
  • each rail rests upon three ball-andsocket joints 11 located at the apices of a triangle and carried on micrometer screws 12 on a base 13. Screws 12 make it possible to adjust the height of each joint 11 and therefore to locate each rail 7 in a perfectly horizontal position.
  • a hydraulic jack body 14 is attached to one of plates 5 of the frame of each assembly, the jack body being appropriately centered by means ofa centering pin. Attached to the other plate of this frame is an opposing plate 15. Piston 16 of the aforesaid hydraulic jack carries at its end a pressure ball 17 protected by a cap 18.
  • each assembly carry sleeves 19 with ball races and protective bellows 25, an arm 20 being attached to each sleeve; the four arms 20 thus guided on these columns carry a mobile element consisting essentially of a plate 21 and a load sensor 22 of conventional type, against which pressure ball 17 of the jack piston rests.
  • Each arm 20 is moreover fitted with a micrometer screw 23 having right and left-hand threads and a knurled wheel 24; accu rate centering of the assemblies.
  • the columns of assembly 2 (which are smaller, this being the low-power assembly) pass between the columns of theother assembly; these columns may be chrome-plated and straightened to ensure perfect guidance.
  • a machine of this kind makes it possible to reduce almost to zero any parasitic stresses which might be introduced as a result of eccentricity of the load during the deformation of the test piece; as already indicated, the only possible source of such stresses in this machine is friction on rails 7, this frictional force being of the order of 5 kg in assembly 1 and 2 kg in assembly 2. These forces, of the order of l/ 12,000 of the maximal load applicable by each assembly, are completely negligeable.
  • a biaxial compression-testing machine which makes it possible to subject a test piece in the form of a right-angled parallelepiped to a biaxial field of compression stresses, said machine comprising two compression assemblies, each of which is called upon to apply a monoaxial compression load to the test piece in a direction horizontal and perpendicular to the load applied by the other assembly and coplanar therewith, each of said assemblies comprising a jack having a body integral with a frame and a piston to apply pressure to a vertical plate adapted to apply a load to one surface of the test piece; an opposing vertical plate coaxial with said first plate and connected to said frame for applying to the opposite parallel surface of the test piece a load of modulus equal to the load applied by said first plate and in the opposite direction thereto, said test machine being characterized in that each compression assembly is carried, independently of the other assembly, on guide means having little friction, said guide means making it possible for the assembly to move freely in a horizontal direction, parallel with the direction of application of the load by said assembly; the guide means associated with the other assembly
  • a testing machine characterized in that said guide means associated with each assembly consist of horizontal rails, the axes of which are parallel with the loading direction of the assembly, the frame of said assembly being supported on said rails by rolling means.
  • a testing machine characterized in that the said rails are located on three ball-joints arranged in the form of a triangle and each mounted on height adjusting means supported on a substantially horizontal base.
  • each compression assembly consists of rigid horizontal columns arranged in parallel with the loading direction of said assembly and jointing together two rigid plates located in the vicinity of each end of said columns, the jack body being attached to one of said plates and the opposing plate to the other, said machine being characterized in that each plate is carried on said columns on low-friction sliding means enabling it to move freely in a direction parallel with said columns thereby acting as guides therefor, the end of the jack piston being adapted to apply pressure to the central area of said plate.
  • a testing machine characterized in that the plate in each assembly is connected to said columns by means of variable-length arms, said arms being equipped with means for adjusting the length thereof for centering said plate.
  • a testing machine characterized in that a load sensor, attached to the plate in each assembly, is interposed between said plate and the end of the jack piston, said sensor serving to transfer to the plate the forces exerted by the piston and to measure said forces.
  • a testing machine designed for testing concrete test pieces, said machine being characterized in that the elements of one of the compression assemblies are of dimensions enabling it to apply a maximal predetermined load to the test piece, while the elements of the other assembly are of dimensions enabling it to apply a maximal load of the order of half of that applied by the first assembly.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
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  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
US00310094A 1971-11-29 1972-11-28 Biaxial compression-testing machine Expired - Lifetime US3797303A (en)

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FR7142699A FR2162717A5 (it) 1971-11-29 1971-11-29

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DE (1) DE2257887A1 (it)
FR (1) FR2162717A5 (it)
GB (1) GB1357679A (it)
IT (1) IT971250B (it)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3975950A (en) * 1975-03-17 1976-08-24 Karoly Erdei Apparatus for testing material strength
US4615221A (en) * 1985-07-03 1986-10-07 The United States Of America As Represented By The Secretary Of The Army Triaxial compression test apparatus
US20030070492A1 (en) * 2001-10-17 2003-04-17 Accentus Plc. Detection of rolling contact fatigue
US20050067333A1 (en) * 2003-09-29 2005-03-31 Unitech, Inc. Method and apparatus for detecting a cracked or broken case
WO2012100780A1 (en) * 2011-01-25 2012-08-02 Aalborg Universitet Shear and tension or compression biaxial material testing fixture
CN104614244A (zh) * 2015-02-13 2015-05-13 武汉科技大学 一种高应力巷道稳定性相似模拟试验装置及试验方法
CN105699203A (zh) * 2016-04-21 2016-06-22 山东大学 一种测量建筑材料在围压下抗压强度的试验装置及方法
US9435724B2 (en) 2014-06-17 2016-09-06 The Boeing Company Test method and fixture for obtaining material properties under biaxial loading
CN108896394A (zh) * 2018-07-13 2018-11-27 中国工程物理研究院总体工程研究所 材料双轴压缩加载装置
CN111766142A (zh) * 2020-06-17 2020-10-13 中国飞机强度研究所 一种壁板压缩试验装置
CN113092247A (zh) * 2021-03-03 2021-07-09 南京理工大学 一种陶瓷预应力的加载装置及其安装方法
CN113092262A (zh) * 2021-03-06 2021-07-09 山东科技大学 基于变形可控承压环的变刚度岩石力学试验系统及试验方法
CN115014961A (zh) * 2022-06-17 2022-09-06 浙江大学 一种高精度大吨位复合材料双轴压缩试验装置及方法
US11499897B2 (en) 2021-03-06 2022-11-15 Shandong University Of Science And Technology Deformation controllable compression ring-based mechanical test system for rocks with variable stiffness and test method thereof

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109883926A (zh) * 2019-03-28 2019-06-14 广西大学 双轴压力作用下混凝土氯离子扩散性能测试系统及其方法

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3975950A (en) * 1975-03-17 1976-08-24 Karoly Erdei Apparatus for testing material strength
US4615221A (en) * 1985-07-03 1986-10-07 The United States Of America As Represented By The Secretary Of The Army Triaxial compression test apparatus
US20030070492A1 (en) * 2001-10-17 2003-04-17 Accentus Plc. Detection of rolling contact fatigue
US6964202B2 (en) * 2001-10-17 2005-11-15 Aea Technology Plc Detection of rolling contact fatigue
US20050067333A1 (en) * 2003-09-29 2005-03-31 Unitech, Inc. Method and apparatus for detecting a cracked or broken case
WO2012100780A1 (en) * 2011-01-25 2012-08-02 Aalborg Universitet Shear and tension or compression biaxial material testing fixture
US9435724B2 (en) 2014-06-17 2016-09-06 The Boeing Company Test method and fixture for obtaining material properties under biaxial loading
CN104614244B (zh) * 2015-02-13 2017-04-12 武汉科技大学 一种高应力巷道稳定性相似模拟试验装置及试验方法
CN104614244A (zh) * 2015-02-13 2015-05-13 武汉科技大学 一种高应力巷道稳定性相似模拟试验装置及试验方法
CN105699203B (zh) * 2016-04-21 2018-05-15 山东大学 一种测量建筑材料在围压下抗压强度的试验装置及方法
CN105699203A (zh) * 2016-04-21 2016-06-22 山东大学 一种测量建筑材料在围压下抗压强度的试验装置及方法
CN108896394A (zh) * 2018-07-13 2018-11-27 中国工程物理研究院总体工程研究所 材料双轴压缩加载装置
CN108896394B (zh) * 2018-07-13 2023-12-29 中国工程物理研究院总体工程研究所 材料双轴压缩加载装置
CN111766142A (zh) * 2020-06-17 2020-10-13 中国飞机强度研究所 一种壁板压缩试验装置
CN111766142B (zh) * 2020-06-17 2023-08-04 中国飞机强度研究所 一种壁板压缩试验装置
CN113092247A (zh) * 2021-03-03 2021-07-09 南京理工大学 一种陶瓷预应力的加载装置及其安装方法
CN113092262A (zh) * 2021-03-06 2021-07-09 山东科技大学 基于变形可控承压环的变刚度岩石力学试验系统及试验方法
CN113092262B (zh) * 2021-03-06 2021-12-24 山东科技大学 基于变形可控承压环的变刚度岩石力学试验系统及试验方法
US11499897B2 (en) 2021-03-06 2022-11-15 Shandong University Of Science And Technology Deformation controllable compression ring-based mechanical test system for rocks with variable stiffness and test method thereof
CN115014961A (zh) * 2022-06-17 2022-09-06 浙江大学 一种高精度大吨位复合材料双轴压缩试验装置及方法

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FR2162717A5 (it) 1973-07-20
IT971250B (it) 1974-04-30
GB1357679A (en) 1974-06-26
DE2257887A1 (de) 1973-06-07

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