The full-scale four-point bending test device and method of steel pipe of additional axial load
Technical field
The present invention relates to submarine pipeline technical field of measurement and test, especially relate to a kind of full-scale four-point bending test device and method of steel pipe of additional axial load.
Background technology
Submarine pipeline is the lifeline of marine oil and gas development of resources, the production to submarine oil and rock gas and the outer defeated critical effect that plays.At present using in the world maximum pipe laying methods is pipelaying vessel metbod, and this method is applicable to the long laying work away from bank apart from pipeline section, and economic target is also better.
In conjunction with pipe laying practical engineering experience both domestic and external, pipelaying vessel metbod mainly contains three kinds: S type laying-out tube process, J type laying-out tube process and pipe crimping type laying-out tube process.Wherein, S type laying-out tube process is because engineering is applied the earliest, and its technology is relatively ripe, becomes the method that current undersea pipe-laying is commonly used the most, and typical S type pipe laying as shown in Figure 1.This pipe laying method generally need to arrange one or many tugboat that casts anchor to support laying work.Before beginning operation, need to be by a positioning of anchor on sea bed, then anchor hawser was drawn to stinger and be tied to the end of first pipe, pipeline is under the support of stinger, naturally bend to S type curve, generally can be divided into two regions: Yi Weigongwan district, the tensioning system from barge deck starts, and extends downwardly into the one section of region (flex point when lifting point is exactly generally pipe bending state) till pipeline starts to depart from the lifting point that stinger supports along stinger; Another section is sagbend region, it is one section of region from flex point to sea bed touchdown point, the rear towing tension that pipeline produces by the stretcher of placing along production line in the curvature of sagbend region is controlled, and the curvature in pipeline Gong Wan district and bending stress generally rely on suitable slideway to support and the curvature of stinger is controlled.
In sum, submarine pipeline is subject to the acting in conjunction of bending, axial tension and radial pressure and seawater drag (distortion) in the time laying simultaneously, its security is subject to very large challenge, and therefore under submarine pipeline pipe laying state, Research on Mechanical Properties seems particularly important.
Submarine pipeline is subject to the effect of gravity and buoyant of sea water as can be seen from Figure 1, S-shaped bending, and maximum distortion appears at pipeline with maximum stress in bend and separates place with stinger.Like this, variation when we just can carry out evaluating combined tube bending with four-point bending test, the maximum deflection radius while paving to determine.
Four-point bending test method is that sample (steel pipe) is placed on two strong points of certain distance, in the mid point same distance from two strong points, sample is applied to downward load, under the effect of 4 contact points, there is four-point bending in sample, and in the bending radius maximum of midpoint.Four-point bending test is mainly used to the bending radius of test sample, the adhesion (as the adhesion of composite bimetal pipe bushing pipe and base tube) that can also test bi-material, the schematic diagram of conventional full-scale steel pipe four-point bending test device as shown in Figure 2 simultaneously.
For composite bimetal pipe, feature according to test objective requirement with four-point bending test method, in conjunction with the special structure of composite bimetal pipe, select four-point bending test method, both the minimal elastic bending radius of composite bimetal pipe can be tested, the minimum bending radius of composite bimetal pipe base lining separation and other bending property of composite bimetal pipe can be tested again.
As shown in Figure 1, in the time of pipe laying, pipeline is not only bending near stinger place or point of the tactile end, also be subject to the acting in conjunction of axial tension and radial pressure and seawater drag (distortion) simultaneously, as shown in Figure 2, maximum deflection radius when conventional full-scale steel pipe four-point bending test is only test steel pipe laying bending change, and ignored steel pipe axial tension factor, and can not test the STRESS VARIATION situation of steel pipe bending radius maximum.
Summary of the invention
The full-scale four-point bending test device and method of steel pipe that the object of the invention is to design a kind of novel additional axial load, addresses the above problem.
To achieve these goals, the technical solution used in the present invention is as follows:
The full-scale four-point bending test device of steel pipe of additional axial load, comprises oil cylinder, pulling force rope, pulling force rope support, two pressure heads and two two test steel pipe supports that arrange on the axis direction of test steel pipe;
Described test steel pipe be positioned over test steel pipe support on, and the length center of described test steel pipe in the spacing of two described test steel pipe supports in the heart;
Two described pressure heads are positioned on described test steel pipe, and the spacing center of two described pressure heads also in the spacing of two described test steel pipe supports in the heart;
The stiff end of described oil cylinder is fixedly installed, and the end face of the movable end of described oil cylinder is pressed on two described test steel pipe supports uniformly, and the spacing that the pressurization center line of described oil cylinder is also arranged in two described test steel pipe supports in the heart;
One end of described test steel pipe is fixed, and the other end connects described pulling force rope; The other end of described pulling force rope is connected to pulling force charger after supporting by described pulling force rope.
Described pulling force rope bearing height to ensure steel pipe reach expection when deformation extent axial load coaxial with steel pipe.
If:
H is the bending drafts of test steel pipe, is determined in the flexural loading degree of trustship place by test steel pipe;
H
1for the height of described test steel pipe support;
H
2for described pulling force rope bearing height;
L
1for the distance of testing the center of steel pipe support described in the centre distance of described oil cylinder;
L
2for the distance at the center of described test steel pipe support and the center of pulling force rope support;
:
。
Be arranged in the described test steel pipe that the spacing of two described test steel pipe supports goes up in the heart and be provided with the foil gauge being connected with stress test system.
Described pulling force rope is wire rope.
Described pulling force charger is external oil cylinder or windlass.
A test method for the full-scale four-point bending test device of steel pipe of additional axial load, comprises that step is as follows:
First, test steel pipe is positioned on test steel pipe support, ensures that the length center of described test steel pipe is in the spacing center of described test steel pipe support;
Secondly, start oil cylinder and pulling force charger, press down and guarantee to test the bending drafts h of steel pipe at the effect push-down head of described oil cylinder, guarantee that by pulling force rope tested steel pipe axial stress is F, meanwhile, the foil gauge being connected with stress test system is monitored and is recorded the real-time strained situation of described test steel pipe under loaded state; Wherein establish:
H
1for the height of described test steel pipe support;
H
2for described pulling force rope bearing height;
L
1for the distance of testing the center of steel pipe support described in the centre distance of described oil cylinder;
L
2for the distance at the center of described test steel pipe support and the center of pulling force rope support;
:
Finally, for composite bimetal pipe, after test completes, whether there is cracking, fold and peel off situation with endoscopic observation liner.
Beneficial effect of the present invention can be summarized as follows:
1, apparatus of the present invention are simple in structure, can be applicable to the simulation force analysis of undersea pipe-laying process, and method is easy to realize, and easy operating;
2, the full-scale steel pipe four-point bending test device of apparatus and method of the present invention routine more of the prior art reflects force-bearing situation when steel pipe is laid more really, and the time result obtaining is relatively more accurate true;
3, the apparatus and method in the present invention not only can be measured full-scale steel pipe minimal elastic bending radius, and strained situation can measure steel pipe stand under load by foil gauge time.
Brief description of the drawings
Fig. 1 S type of the prior art laying-out tube process schematic diagram;
Wherein, 21 surface levels, 22 sea beds, 23 touch end points, and 24 inflection points are to part between sea bed, 25 inflection points, 26 stinger parts, 27 lift away from a little, 28 pipelaying barges.
Fig. 2 is the full-scale steel pipe four-point bending test of routine of the prior art device schematic diagram.
Fig. 3 is the steel pipe four-point bending test device schematic diagram of the additional axial load of invention.
Fig. 4 is the steel pipe four-point bending test device practical operation schematic diagram of the additional axial load of invention.
Embodiment
In order to make technical matters solved by the invention, technical scheme and beneficial effect clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.
The full-scale four-point bending test device of steel pipe of a kind of additional axial load as shown in Figure 3 and Figure 4, comprises that oil cylinder 4, pulling force rope 6, pulling force rope support 7, two pressure heads 5 and two two test steel pipe supports 2 that arrange on the axis direction of test steel pipe 1; Described test steel pipe 1 be positioned over test steel pipe support 2 on, and the length center of described test steel pipe 1 in the spacing of two described test steel pipe supports 2 in the heart; Two described pressure heads 5 are positioned on described test steel pipe 1, and the spacing center of two described pressure heads 5 also in the spacing of two described test steel pipe supports 2 in the heart; The stiff end of described oil cylinder 4 is fixedly installed, and the end face of the movable end of described oil cylinder 4 is pressed on two described test steel pipe supports 2 uniformly, and the spacing that the pressurization center line of described oil cylinder 4 is also arranged in two described test steel pipe supports 2 in the heart; One end of described test steel pipe 1 is fixed, and the other end connects described pulling force rope 6; The other end of described pulling force rope 6 is connected to pulling force charger after supporting 7 by described pulling force rope.
In the embodiment being more preferably, when described pulling force rope supports 7 height and will ensure that steel pipe reaches expection deformation extent, axial load is coaxial with steel pipe.
In the embodiment being more preferably, establish:
H is the bending drafts of test steel pipe 1, is determined in the flexural loading degree of trustship place by test steel pipe 1;
H
1for the height of described test steel pipe support 2;
H
2for described pulling force rope supports 7 height;
L
1for the distance of testing the center of steel pipe support 2 described in the centre distance of described oil cylinder 4;
L
2for the distance at the center of described test steel pipe support 2 and the center of pulling force rope support 7;
:
In the embodiment being more preferably, be arranged in the described test steel pipe 1 that the spacing of two described test steel pipe supports 2 goes up in the heart and be provided with the foil gauge 3 being connected with stress test system.
In the embodiment being more preferably, described pulling force rope 6 is wire rope.Described pulling force charger is external oil cylinder 4 or windlass.
A test method for the full-scale four-point bending test device of steel pipe of additional axial load, comprises that step is as follows:
First, test steel pipe 1 is positioned on test steel pipe support 2, ensures that the length center of described test steel pipe 1 is in the spacing center of described test steel pipe support 2;
Secondly, start oil cylinder 4 and pulling force charger, press down and guarantee to test the bending drafts h of steel pipe 1 at the effect push-down head 5 of described oil cylinder 4, guaranteeing to test steel pipe 1 axial stress by pulling force rope 6 is F, meanwhile, the foil gauge 3 being connected with stress test system is monitored and is recorded the real-time strained situation of described test steel pipe 1 under loaded state; Wherein establish:
H
1for the height of described test steel pipe support 2;
H
2for described pulling force rope supports 7 height;
L
1for the distance of testing the center of steel pipe support 2 described in the centre distance of described oil cylinder 4;
L
2for the distance at the center of described test steel pipe support 2 and the center of pulling force rope support 7;
:
In the embodiment being more preferably, last, for composite bimetal pipe, after test completes, whether there is cracking, fold and peel off situation with endoscopic observation liner.
In certain preferred embodiment, in Fig. 3, F is axial load, is determined by the stretcher tension force in laying, and the loading of axial stress is supplied by external oil cylinder or windlass; Foil gauge 3 is for monitoring the real-time strained situation of steel pipe under loaded state; When oil cylinder 4 ensures four-point bending, depress stress, make to support 2 and form 4 stresses of steel pipe with pressure head 5; Wire rope 6 one end are connected with steel pipe 1, and the other end is connected with external oil cylinder or windlass, for steel pipe 1 provides corresponding axial stress F.F size is by designing root border condition of construction calculating gained factually.
In Fig. 3, there is following relation:
In formula (1),
H---for pressure head 5 drafts of testing requirements (are tested the bending drafts of steel pipe 1 h), are determined in the flexural loading degree of trustship place by steel pipe;
H1---bearing height;
H2---wire rope bearing height, ensure steel pipe reach expection when deformation extent axial load coaxial with steel pipe;
The distance of L1---oil cylinder 4 centre distance centres of support;
The distance at L2---centre of support and wire rope center.
As shown in Figure 4, its operation engineering is as described below for the practical operation schematic diagram of this device:
First, test steel pipe 1 is positioned over and is supported on 2, ensure that steel pipe 1 length center is in support 2 spacing centers; Secondly, start oil cylinder 4 and external windlass, guarantee the bending drafts h of steel pipe 1 by pressure head 5, guarantee steel pipe axial stress F by wire rope.Meanwhile, the foil gauge 3 being connected with stress test system, can monitor and record the real-time strained situation of steel pipe under loaded state.Finally, for thermometal coincidence tube, the situation such as can whether have cracking, fold with endoscopic observation liner after test completes and peel off.
Visible, apparatus of the present invention are simple in structure, can be applicable to the simulation force analysis of undersea pipe-laying process, and method is easy to realize, and easy operating; The full-scale steel pipe four-point bending test device of apparatus and method of the present invention routine more of the prior art reflects force-bearing situation when steel pipe is laid more really, and the time result obtaining is relatively more accurate true; Apparatus and method in the present invention not only can be measured full-scale steel pipe minimal elastic bending radius, and strained situation can measure steel pipe stand under load by foil gauge 3 time.
More than by the detailed description of concrete and preferred embodiment the present invention; but those skilled in the art should be understood that; the present invention is not limited to the above embodiment; within the spirit and principles in the present invention all; any amendment of doing, be equal to replacement etc., within protection scope of the present invention all should be included in.