CN101806689B - Method for measuring dynamic shear strength of brittle material by using concentric cylindrical sample - Google Patents

Abstract

The invention provides a method for measuring the dynamic shear strength of a brittle material by using a concentric cylindrical sample, which comprises the following steps of: mounting the concentric cylindrical sample on a Hopkinson pressure testing device; applying loaded force to two axial ends of the concentric cylindrical sample; and using the loaded force, an elastic module E of a Hopkinson pressure bar, the circular cross-sectional area of the Hopkinson pressure rod, the radius R of an internal cylinder of the concentric cylindrical sample and the overlapped height H of the internal cylinder and an external cylinder of the concentric cylindrical sample to calculate the dynamic shear strength tau d of the material according to the following formula, wherein in the formula, epsilon I(t) is an incident strain pulse, epsilon R(5) is a reflection strain pulse, and epsilon T(t) is a transmission strain pulse. By using the method, the dynamic shear strength of which the loading rate section is between 105 and 106 MPa/s can be acquired, and the blank in the research field is filled up.

Description

Utilize the method for concentric cylindrical sample measuring dynamic shear strength of brittle material

Technical field

The invention belongs to the material properties test field, relate to a kind of method of utilizing the concentric cylindrical sample measuring dynamic shear strength of brittle material.

Technical background

The shearing-resistance characteristic of hard brittle materials such as rock is a kind of very important characteristic.Being used to measure the hard brittle material shear behavior at present mainly is to adopt the test of angle plate and two (list) face scissor test.Above-mentioned two kinds of experiments are under static state or the quasistatic (10 ^-1～10 ¹MPa/s) shear test.For under the high LOADING RATES (10 ⁵～10 ⁶MPa/s) dynamic shear strength owing to be subjected to the restriction of present means of testing, can't be tested always.

Summary of the invention

Technical matters to be solved of the present invention is to propose to utilize the method for concentric cylindrical sample measuring dynamic shear strength of brittle material.

Technical solution of the present invention is as follows: a kind of method of utilizing the concentric cylindrical sample measuring dynamic shear strength of brittle material, it is characterized in that, concentric cylindrical sample is installed on the Huo Bujinsen pressure test device, axial two ends to concentric cylindrical sample apply loading force, utilize the bullet mould E of loading force, Huo Bujinsen press rods, the circular cross section of Huo Bujinsen press rods to amass the radius R of the inner cylinder of A, concentric cylindrical sample, the overlapping height H of inside and outside cylinder of concentric cylindrical sample, be calculated as follows the dynamic shear strength τ that obtains material _d:

${\mathrm{\τ}}_d=\frac{\mathrm{EA}}{4\mathrm{\πRH}}[{\mathrm{\ϵ}}_I\left(t\right)+{\mathrm{\ϵ}}_R\left(t\right)+{\mathrm{\ϵ}}_T\left(t\right)];$

In the formula: ε _I(t) be incident strain-pulse, ε _R(t) be reflection strain-pulse, ε _T(t) be the transmission strain-pulse.

Described concentric cylindrical sample is made up of two inner cylinder and exterior cylindrical that with one heart and highly equate, and an end of inner cylinder stretches out from an end of exterior cylindrical.

Beneficial effect:

Utilize said method, can obtain LOADING RATES section (10 ⁵～10 ⁶MPa/s) dynamic shear strength has been filled up the blank in this research field.

At present under the static state of test material or quasistatic in the shearing strength experiment, material sample is mainly made cube or square bodily form formula, utilizes the test of angle plate or two (list) face scissor test method to test then.Utilize above-mentioned two kinds of methods,, can only obtain LOADING RATES section 10 by regulating experimental system loading speed scope ^-1～10 ¹The shearing strength of MPa/s material, the experiment under the higher LOADING RATES can't be finished by the static load experimental machine.For the LOADING RATES section is 10 ⁵～10 ⁶The dynamic performance testing experiment of MPa/s material, the main at present Huo Bujinsen device that adopts.Because the cross section of incident bar and transmission bar be circular in the Huo Bujinsen experimental system, therefore can carry out impact compress or impact the splitting experiment (impact compress and impact in the splitting material sample be shaped as cylindrical, material sample shape unanimity in testing with static load).Be subjected to the restriction of Huo Bujinsen bar cross sectional shape, can't directly apply to the sample of square shape in the static load shearing resistance experiment and impact the shearing resistance experiment on the Huo Bujinsen device, the LOADING RATES section is 10 ⁵～10 ⁶The shear behavior test of MPa/s material can't realize always.Therefore, (promptly require in sample, to have a shear surface in conjunction with the characteristics of Huo Bujinsen experimental provision (promptly require the round section of incident bar and transmission bar is complementary in the xsect of sample and the Huo Bujinsen experimental provision) and the requirement of material shear behavior test, shear surface in this sample is that ring surface that 2 cylinders stagger mutually), the present invention proposes the method for utilizing the concentric cylindrical sample measuring dynamic shear strength of brittle material.At present Huo Bujinsen experimental provision and experimental principle thereof are very ripe and be used widely, the present invention is by the shape of design sample, and impact the shearing resistance experiment based on the experimental principle of Huo Bujinsen, the precision of experimental result and accuracy can be guaranteed.

Description of drawings

Dynamic shear test synoptic diagram on Fig. 1 SHPB device;

Fig. 2 specimen shape floor map;

Fig. 3 specimen shape schematic perspective view.

Number in the figure explanation: 1-shock load, 2-incident bar, 3-foil gauge, 4-concentric cylindrical sample, 5-transmission bar, 6-absorbing rod.

Embodiment

Below with reference to figure and specific implementation process the present invention is described in further details:

Embodiment 1:

Embodiment 1. is at SHPB (Split Hopkinson Pressure Bar, the Huo Bujinsen press rods, be called for short SHPB) during the enterprising action attitude shear test of device, choose outer dia and be 50mm, highly be the column type sample of 30mm, the inner cylinder diameter is 25～30mm, highly for 30mm, inner cylinder and exterior cylindrical interlace, and inner cylinder stretches out 10mm (seeing Fig. 2 and 3).The incident bar that sample is lain against the SHPB device also closely contacts with transmission bar is middle, the other end at incident bar applies shock load then, note the transmission strain-pulse in the incident strain-pulse in the incident bar in the impulse test process, reflection strain-pulse and the transmission bar, be calculated as follows the dynamic shear strength that can obtain material:

${\mathrm{\τ}}_d=\frac{\mathrm{EA}}{4\mathrm{\πRH}}[{\mathrm{\ϵ}}_I\left(t\right)+{\mathrm{\ϵ}}_R\left(t\right)+{\mathrm{\ϵ}}_T\left(t\right)]$

In the formula: τ _dBe shearing strength (MPa) that E is to be the bullet mould (MPa) of Huo Bujinsen press rods, A is the long-pending (mm of the circular cross section of Huo Bujinsen press rods ²), ε _I(t) be incident strain-pulse, ε _R(t) reflection strain-pulse, ε _T(t) be the transmission strain-pulse, R is the radius (mm) of sample inner cylinder, and H is the overlapping height of inside and outside cylinder (mm).

E is the bullet mould of Huo Bujinsen press rods, and this amount is demarcated in the process that the Huo Bujinsen experimental system is installed, and belongs to constant.A, R and H can utilize scale or vernier caliper to measure.ε _I(t), ε _R(t) and ε _T(t) utilize the Huo Bujinsen experimental system to obtain.

Claims (1)

1. method of utilizing the concentric cylindrical sample measuring dynamic shear strength of brittle material, it is characterized in that, concentric cylindrical sample is installed on the Huo Bujinsen pressure test device, axial two ends to concentric cylindrical sample apply loading force, utilize the bullet mould E of loading force, Huo Bujinsen press rods, the circular cross section of Huo Bujinsen press rods to amass the radius R of the inner cylinder of A, concentric cylindrical sample, the overlapping height H of inside and outside cylinder of concentric cylindrical sample, be calculated as follows the dynamic shear strength τ that obtains material _d:

${\mathrm{\τ}}_d=\frac{\mathrm{EA}}{4\mathrm{\πRH}}[{\mathrm{\ϵ}}_I\left(t\right)+{\mathrm{\ϵ}}_R\left(t\right)+{\mathrm{\ϵ}}_T\left(t\right)];$

In the formula: ε _I(t) be incident strain-pulse, ε _R(t) be reflection strain-pulse, ε _T(t) be the transmission strain-pulse; Dynamic shear strength τ _dUnit be MPa, the unit of the bullet mould E of Huo Bujinsen press rods is MPa, the unit of the long-pending A of the circular cross section of Huo Bujinsen press rods is mm ², the unit of the overlapping height H of inside and outside cylinder of the radius R of the inner cylinder of concentric cylindrical sample and concentric cylindrical sample is mm;

Described concentric cylindrical sample is made up of two inner cylinder and exterior cylindrical that with one heart and highly equate, and an end of inner cylinder stretches out from an end of exterior cylindrical.

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