Back to results
US 2016/0273997 A1Published application
Low cycle fatigue testing
AssigneeDmar Engineering, Inc.
InventorsZHIMING HUANG, DAGANG ZHANG
Life of this patent
Estimating the term…
Abstract
Apparatus and methods related to low cycle fatigue testing are described. For example, some embodiments may contain a control box, two fitting connections, a pressure gauge, a plurality of clamps, a plurality of hydraulic cylinders, a plurality of control cables, and a strain gauge, for testing the low cycle fatigue properties of a testing specimen, for example, a steel tube umbilical.
Claims20
1:
- An apparatus for low cycle fatigue testing on a testing specimen, comprising:
- a control box;
- a plurality of control cables;
- a plurality of hydraulic cylinders;
- a plurality of clamps;
- and
- a strain gauge.
4 more elements
2:
- An apparatus according to claim 1, further comprising two fitting connections.
3:
- An apparatus according to claim 2, wherein the two fitting connections are connected to a tube-shaped testing specimen at its two ends.
4:
- An apparatus according to claim 2, further comprising a pressure gauge.
5:
- An apparatus according to claim 4, wherein the pressure gauge is connected to one of the two fitting connections.
6:
- An apparatus according to claim l, wherein the clamps are flexibly positioned along a tube-shaped testing specimen.
7:
- An apparatus according to claim 1, wherein the clamps consist of two half shells that can be assembled together through bolts to hold the testing specimen in place.
8:
- An apparatus according to claim 1, wherein the clamps are connected to the hydraulic cylinders through pivot pins.
9:
- An apparatus according to claim 1, wherein the strain gauge is attached to the testing specimen on or near the weld or joint connection area of the testing specimen.
10:
- An apparatus according to claim 1, wherein the control box is connected to the strain gauge through the control cable to receive the strain value continuously.
11:
- An apparatus according to claim 10, wherein the control box is receiving the strain value from the strain gauge and displaying it in real time.
12:
- An apparatus according to claim 1, wherein the control box is connected to the hydraulic cylinder through the control cable to instruct the hydraulic cylinder to extend or retract in a certain pattern.
13:
- An apparatus according to claim 1, wherein the testing specimen is tube-shaped and has a length of 0.5 meter to 5 meters.
14:
- An apparatus according to claim 1, wherein the testing specimen is tensioned during the low cycle fatigue testing.
15:
- An apparatus according to claim 14, wherein the tension is achieved through internal pressure, a clump weight, an external hydraulic cylinder, or two clamps at the two ends of the testing specimen.
16:
- A method for low cycle fatigue testing on a testing specimen, comprising:
- attaching a strain gauge to an area on the surface of the testing specimen;
- connecting the strain gauge with a control box via a control cable;
- attaching a plurality of clamps along the length of the testing specimen;
- attaching the clamps to a plurality of hydraulic cylinders;
- and
- connecting the hydraulic cylinders with the control box via a plurality of control cables.
4 more elements
17:
- A method according to claim 16, wherein the strain gauge is placed on or near the weld or joint connection area of the testing specimen.
18:
- A method according to claim 16, wherein the testing specimen is a tube that can be filled with water or other testing fluid at a desired pressure that can be continuously monitored by a pressure gauge.
19:
- A method according to claim 16, wherein the control box is a computer with suitable peripherals capable of receiving signals from the strain gauge, analyzing the signals to find out the bending status of the testing specimen, and sending signals to hydraulic cylinders to adjust the cylinder extension and retraction pattern, to control the low cycle fatigue testing automatically based on predefined testing purposes.
20:
- A method according to claim 18, wherein the minimum curvature and maximum curvature are set in the control box, and the control box instructs the hydraulic cylinders to bend the testing specimen until the maximum curvature is reached at the strain gauge, and reverse the bending to the minimum curvature, and repeat the bending process until the pressure gauge indicates a tube leakage failure, when the corresponding bending cycle number is recorded by the control box.