CN105628491A

CN105628491A - Metal plate two-way stretching large-deformation thickened test piece

Info

Publication number: CN105628491A
Application number: CN201510997137.3A
Authority: CN
Inventors: 赵坤民; 陈梁玉; 丁志杨; 陈还; 吴寒; 严建文
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2015-12-24
Filing date: 2015-12-24
Publication date: 2016-06-01
Anticipated expiration: 2035-12-24
Also published as: CN105628491B

Abstract

The invention discloses a metal plate two-way stretching large-deformation thickened test piece. The metal plate two-way stretching large-deformation thickened test piece is of a cross structure divided into four cross arms and a central crossed area. The four cross arms are equal in length and width, thickening plates are symmetrically arranged on the upper side and the lower side of each arm, and thus a three-layer composite plate structure is formed. According to the metal plate two-way stretching large-deformation thickened test piece, the feature of a test area material is not changed, the load transmitting capability of the cross arms is enlarged, stress concentration in a transition area between every two adjacent cross arms is relieved, large test piece central area deformation is obtained, and thus the practicability of stress strain of the test material in a two-way stretching test is improved.

Description

Sheet metal two-way stretch gross distortion increases thick test specimen

Technical field

A kind of sheet metal two-way stretch gross distortion of the present invention increases thick test specimen, is specially the test specimen of sheet material biaxial tensile test, belongs to plastic forming technical field.

Background technology:

In plastic forming field, plastic yielding behavior is important research focus always, especially along with the sheet material of many novel procesies, new texture, plastics on new materials and the continuous release of some new forming technologies, to the key accurately determining to obtain precise results in economics analysis and finite element analysis of yield behavior (comprising initial surrender and follow-up surrender).

Traditional test method for yield behavior research has certain limitation. The test of application thin-walled tube under thrust load and interior pressure, thrust load and torsional load effect can realize different strain pathses, but pipe fitting and sheet material have a certain distance in performance; Available singly draw the combination of the fundamental test such as test, plectane bulging test, Plane Strain Test and compression testing, but only can obtain as singly drawn, plane strain or etc. two draw the particular data such as a little. At present, dull and stereotyped shape test specimen is adopted to carry out two Main way drawing test to become recent.

Dull and stereotyped shape test specimen is two to be drawn in test, and cruciform two-way stretch becomes recent research focus. Along with the development of experimental installation precision manufactureing and Computer Control Technology, cruciform biaxial tensile test become research complex loading strain paths method the most easily, particularly its have can directly computed stress, strain numerical value advantage. By the load of restrained stretching diaxon or displacement size, the pulling force ratio changing test specimen diaxon makes central section obtain different stress-strain states, it is achieved complex loading, obtains different loading paths Xia Shuanla district Stress distribution, sets up relevant yield situation. Plane crisscross test specimen two-way stretch experimental technique was just suggested as far back as the sixties in 20th century, but until just obtain some in recent years and break through, obtained relevant application.

The main problem of restriction plane crisscross test specimen two-way stretch experimental applications has:

1) design of cruciform biaxial tension test piece and preparation, solve that test specimen central section Stress distribution is uneven, fillet place stress concentrate relatively big, diaxon load to interfere with each other, be out of shape irregular and realize central section large deformation problem;

2) the measurements and calculations method of test specimen central section stress, strain, the especially problem identificatioin of central section stress;

3) control of biaxial tensile loading mode, to realize different two drawing loadings, without unloading the different load path such as non-proportion loading and bilinearity loading. At present, solving preferably for the 3rd problem, crucial problem is the problems of measurement solving central section gross distortion, unbalance stress and central section stress, and emphasis is the design of cruciform test specimen.

Realizing all even gross distortion of central section stress distribution, both both connected each other, but specific implementation has again conflicting place. Investigator devises the cruciform test specimen of multiple multi-form central section and cross arm.

In order to solve the uneven problem of central section normal stress, on arm, the cruciform test specimen of fluting/seam type is suggested, but the test specimen central section distortion amount that test obtains also is limited.

The form of cruciform test specimen roughly has several as follows: coventional type, fluting/seam type on arm, and on arm, fluting/seam and central section subtract slim, fillet type, cross arm is interlayer (reinforcement) type, trapezoidal cross arm type, and cross arm is that on trapezoidal, arm, fluting/seam and central section subtract slim.

In the cruciform test specimen that these are multi-form, so that arm to crack/research of grooved is maximum, advantage be arm cracks/groove can reduce the shearing stress even eliminating central section greatly, thus the principal axis of stress in center deformation district and draw direction are overlapped, like this can the stress value of convenient survey calculation central section; Its shortcoming is that strengthening material is only just suitable for by this kind of test specimen, and central section distortion can not be very big, because only after the metal in seam/groove region has entered the strengthening stage, multi-center trial district stress just can reach sufficiently high level, often occurs the situation that cross arm ruptures prior to central section. Central section subtracts slim test specimen can make central section produce moderate finite deformation, but this kind of test specimen adds the change needing to consider the original attribute of material after metal-stripping man-hour, and the first inefficacy of central section and thinning area boundary can hide some material natural characteristics. Considering the ununiformity of the actual microtexture of surface irregularity steel plate and the uneven of thickness distribution, central section subtracts thin cross tension specimen and is not suitable for microcosmic that gross distortion brings out or the research that macro-mechanical property changes.

Summary of the invention

The present invention is the deficiency overcoming above-mentioned research existence, utilize and increase thick principle, devise a kind of sheet metal two-way stretch gross distortion and increase thick test specimen, to test zone material self character can not be changed, the transmission loading capacity of cross arm can be increased, the stress reducing zone of transition between adjacent two cross arms is concentrated, and obtains bigger test specimen central section distortion amount, thus has expanded the practicality of biaxial tensile test test material stress-strain.

The present invention is that technical solution problem adopts following technical scheme:

The present invention's a kind of sheet metal two-way stretch gross distortion increases the feature of thick test specimen: described biaxial tension test piece is cruciform; Described cruciform is divided into four cross arms and central crossbar district; Described four cross brachium width are equal, and upper and lower surface is symmetrically arranged with increasing slab, thus form three-layer composite board structure.

The feature that sheet metal two-way stretch gross distortion of the present invention increases thick test specimen is also:

Circular arc cutaway is offered between described adjacent two cross arms; It is connected for tangent between described circular arc cutaway and the cross arm of both sides;

Increasing slab on described four cross arms extends respectively to direction, described central crossbar district, and the central point extending to described central crossbar district is till peripheral one week.

It is arc transition between described adjacent two cross arms;

Increasing slab on described four cross arms extends respectively to direction, described central crossbar district, forms extension portion, and described extension portion is not in contact with each other at place of described central crossbar district.

It is convex transitional between described adjacent two cross arms;

Compared with the prior art, the useful effect of the present invention is:

1, the present invention by gluing be aided be welded on proof strength while realize increasing thick, do not change test zone material self character, avoid the shortcoming that after subtracting metal-stripping that slim test specimen brings, the original attribute of material changes; Increase the transmission loading capacity of cross arm, the premature failure of prevention cross arm is had unusual effect, thus makes test specimen central crossbar district can reach gross distortion.

2, the first test specimen of the present invention is namely around the peripheral one week incrassation type cruciform test specimen of central point, circular arc cutaway is offered between adjacent two cross arms, it is connected for tangent between circular arc cutaway and the cross arm of both sides, it is possible between lower arm, the stress of zone of transition is concentrated and effectively reduced central region cross sectional area simultaneously thus increase the distortion amount in central crossbar district.

3, namely the present invention's the 2nd kind of test specimen extend the formula incrassation type cruciform test specimen that is not in contact with each other to center, is arc transition between adjacent two cross arms, it is possible to the stress reducing zone of transition between arm is concentrated; Increase thick near test specimen center, it is possible to increase the transmission loading capacity of cross arm.

4, namely the third test specimen of the present invention extends the formula that is not in contact with each other and increases protruding connecting-type cruciform test specimen between thick and arm to center, it is convex transitional between adjacent two cross arms, employing die stamping is shaped, it is possible to the too early cracking of zone of transition between prevention arm, thus makes central crossbar district reach gross distortion.

Accompanying drawing explanation

Fig. 1-a is the axonometric drawing around the peripheral one week incrassation type cruciform test specimen of central point;

Fig. 1-b is the front view around the peripheral one week incrassation type cruciform test specimen of central point;

Fig. 1-c is the A-A face complete section partial enlarged view of Fig. 1-b;

Fig. 2-a is the axonometric drawing extending the formula incrassation type cruciform test specimen that is not in contact with each other to center;

Fig. 2-b is the front view extending the formula incrassation type cruciform test specimen that is not in contact with each other to center;

Fig. 2-c is the A-A face complete section partial enlarged view of Fig. 2-b;

Fig. 3-a extends the front view that the formula that is not in contact with each other increases protruding connecting-type cruciform test specimen between thick and arm to center;

Fig. 3-b is the A-A face complete section partial enlarged view of Fig. 3-a;

Fig. 3-c extends the axonometric drawing that the formula that is not in contact with each other increases protruding connecting-type cruciform test specimen between thick and arm to center;

Fig. 3-d is the B district enlarged view of Fig. 3-c;

Sequence number in figure: 1 increasing slab.

Embodiment

A kind of sheet metal two-way stretch gross distortion increases thick test specimen, adopts cruciform, is divided into four cross arms and central crossbar district, and four cross brachium width are equal, and upper and lower surface is symmetrically arranged with increasing slab 1, thus forms three-layer composite board structure; Increase slab 1 gluing in test specimen two sides, increase slab edge and adopt the art breading such as resistance welding, electric-arc welding, Laser Welding, ultrasonic wave weldering, do not change test zone material self character, realize while proof strength increasing this effect thick, and then increase the transmission loading capacity of cross arm, increase the distortion amount in test specimen central crossbar district.

Below in conjunction with drawings and Examples, the technical scheme of the present invention is described further.

Embodiment one:

See Fig. 1-a, Fig. 1-b and Fig. 1-c, the present embodiment is that the first test specimen is namely around the peripheral one week incrassation type cruciform test specimen of central point, circular arc cutaway is offered between adjacent two cross arms, it is connected for tangent between circular arc cutaway and the cross arm of both sides, it is possible between lower arm, the stress of zone of transition is concentrated and effectively reduced central region cross sectional area simultaneously thus increase the distortion amount in central crossbar district.

Increasing slab 1 on four cross arms extends respectively to direction, central crossbar district, and the central point extending to central crossbar district is till peripheral one week, and namely the part of the symmetrical gluing two pieces condition of equivalent thickness in test specimen two sides realizes around the peripheral Zhou Zenghou of central point.

Embodiment two:

See Fig. 2-a, Fig. 2-b and Fig. 2-c, the present embodiment is that namely the 2nd kind of test specimen extend the formula incrassation type cruciform test specimen that is not in contact with each other to center, is arc transition, concentrates to reduce the stress of zone of transition between arm between adjacent two cross arms;

Increasing slab 1 on four cross arms extends respectively to direction, central crossbar district, form extension portion, extension portion is not in contact with each other at place of central crossbar district, namely the part of symmetrical gluing eight condition of equivalent thickness in four cross arm two sides realizes extending the formula that is not in contact with each other to center and increases thick, thus increases the transmission loading capacity of cross arm.

Embodiment three:

See Fig. 3-a, Fig. 3-b, Fig. 3-c and Fig. 3-d, the present embodiment increases protruding connecting-type cruciform test specimen between thick and arm for namely the third test specimen extends the formula that is not in contact with each other to center, it is convex transitional between adjacent two cross arms, protruding employing die stamping is shaped, the too early cracking of zone of transition between prevention arm, thus make central crossbar district reach gross distortion;

Increasing slab 1 on four cross arms extends respectively to direction, central crossbar district, forms extension portion, and extension portion is not in contact with each other at place of central crossbar district, i.e. the part of symmetrical gluing eight condition of equivalent thickness in test specimen two sides, thus increases the transmission loading capacity of cross arm.

Claims

1. sheet metal two-way stretch gross distortion increases a thick test specimen, it is characterized in that: described biaxial tension test piece is cruciform; Described cruciform is divided into four cross arms and central crossbar district; Described four cross brachium width are equal, and upper and lower surface is symmetrically arranged with increasing slab, thus form three-layer composite board structure.

2. sheet metal two-way stretch gross distortion according to claim 1 increases thick test specimen, it is characterized in that: offer circular arc cutaway between described adjacent two cross arms; It is connected for tangent between described circular arc cutaway and the cross arm of both sides;

3. sheet metal two-way stretch gross distortion according to claim 1 increases thick test specimen, it is characterized in that: be arc transition between described adjacent two cross arms;

4. sheet metal two-way stretch gross distortion according to claim 1 increases thick test specimen, it is characterized in that: be convex transitional between described adjacent two cross arms;