GB2094476A - Stress monitoring apparatus - Google Patents
Stress monitoring apparatus Download PDFInfo
- Publication number
- GB2094476A GB2094476A GB8106954A GB8106954A GB2094476A GB 2094476 A GB2094476 A GB 2094476A GB 8106954 A GB8106954 A GB 8106954A GB 8106954 A GB8106954 A GB 8106954A GB 2094476 A GB2094476 A GB 2094476A
- Authority
- GB
- United Kingdom
- Prior art keywords
- probability
- ship
- stress
- exceeded
- data processor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D1/00—Measuring arrangements giving results other than momentary value of variable, of general application
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Or Calibration Of Command Recording Devices (AREA)
Abstract
A data processor 10 controls the sampling of a plurality of strain gauge transducer units 14 distributed along the bottom plating structure of a ship. For each sampling cycle, of which there may be one thousand per second, the maximum stress is determined using a curve fitting algorithm and the stress measurements for some period, say the last two minutes, are stored in a memory 12. The data processor operates upon these measurements and determines the probability of a predetermined level being exceeded. The calculated probability is displayed on a display device 18 or an alarm device 20 may be operated when the probability rises to a particular value. The Officer on the bridge of the ship is thus warned when the probability of an unsafe stress level being exceeded becomes too high and can then take remedial action such as reducing speed or even preparing to abandon ship. The invention can be applied to other structure subjected to wind, water, other fluid or mechanical forces fluctuating over a very wide range. <IMAGE>
Description
SPECIFICATION
Stress monitoring apparatus
The present invention relates to apparatus for monitoring the stresses experienced by a fixed or moving structure which is subjected to fluctuating loads. The invention is particularly, but not exclusively, applicable to structures in the ocean subjected to the forces of waves. The structure may then be a vessel or a fixed oil rig for example.
The invention may also be applied to structures subject to fluctuating aerodynamic or other fluid or mechanically induced stresses.
It is known that the stresses arising at sea from the elements vary over an exceedingly wide range
and, when weather conditions are severe, there is
a certain probability of a freak wave or gust of
wind which can be extremely dangerous for a ship
or other structure. Although techniques for
calculating probabilities of stress levels being
exceeded in such circumstances are well known in
themselves, there exists no convenient way of taking advantage of that knowledge in the
practical situation of a ship at sea, an off-shore oil
rig and so on.
Considerable work has also been done in
collecting statistical data on stresses in ships. See
for example a paper by Ward and Katory "Data on
Midship Bending Stresses from Four Ships"
published in International Symposium on the
Dynamics of Marine Vehicles and Structures in
Waves, April 1974, University College London.
This paper describes research undertaken by the
British Ship Research Association. In this research
strain gauges were installed in a number of ships
and data were collected over substantial periods
and recorded on tape for subsequent analysis. The
purpose of the analysis was to predict stresses
under various weather conditions etc with a view
to improving ship design. Again this work did not
relate to any system of practical use at sea.
The object of the present invention is to provide
an apparatus with a continuous monitoring function
whereby it is possible always to be made aware
of ruling conditions, to the end that remedial
or avoiding action can be taken when there is a
certain probability of an unacceptable stress level
being exceeded. In some situations remedial
action may be taken automatically; in other
situations the apparatus may simply give a warning
calling for human intervention. The nature of the -action taken will depend upon the nature of the
structure in which stresses are monitored. In the
case of a ship the first action may simply be to
reduce speed. In the case of an oil rig, or at a very
high probable stress level in a ship, it may be
appropriate to signal a warning to prepare to
abandon or actually abandon the ship or rig.
According to the present invention there is
provided apparatus for monitoring stresses in a
structure comprising at least one strain transducer
providing a signal representing the strain in part of
the structure, data processing means responsive
to the signal from the or each transducer over a
period of time to determine in accordance with a predetermined probability function or functions the probability of a predetermined strain and consequent stress level being exceeded, and means for providing an indication of the probability thus determined.
The indication may be given as a continuous digital or analogue readout or intermittent printout of the probability itself which in practical terms may lie in the range 102 to 108. In other words, it is indicated where the probability lies in a range from 1 in a 100 to 1 in a 100 million. An alternative is simply to indicate when the probability increases above one or more threshold values. The probability information may be supplemented with an indication of the trend thereof which will be given simply as the sign of the rate of change of the probability with time or as the algebraic value of the rate of change of probability.
In the simplest application the digital or analogue processing means may sample the strain signal(s) at regular intervals and allocate each processed measurement to one of a plurality of small stress ranges. The processing means also total the number of measurements in each range, so that, a histogram of frequency distribution can be constructed. From the histogram, using known mathematical techniques, it is possible to determine the mean stress value and the standard deviation or other measure of dispersion of the stress values, related to a Gaussian, Rayleigh or any other relevant distribution function appropriate to the structure being monitored and the stresses to which it is subjected. Given the mean and say the standard deviation, it is a staight forward and well known calculation to determine the probability of exceeding any given stress value.
In a more sophisticated approach a double
exponential distribution function is employed, e.g.
as described in the aforementioned paper by Ward and Katory.
A practical system embodying the invention
will now be described by way of example with
reference to the sole figure of the accompanying
drawings, showing the main elements of the
system in block diagram form. Overall control of the system is effected by a data processor 10, e.g. a
microprocessor dedicated to this function. The
data processor has at its disposal a memory 12
which can incorporate a ROM for programme
information and a RAM for stage of data collected
and processed. The data processor communicates
with a plurality of transducer stations 1 4 by way
of an interface unit 1 6. Two transducer stations
are shown by way of example although it is
preferred to utilise more, say four stations. Each transducer station comprises a strain gauge, an anaiogue-to-digital converter and means for sampling the analogue-to-digital converter.The strain gauges are spaced along the bottom plating structure of a ship and the output of each gauge is sampled at say one thousand times per second.
The data processor 10 can poll the transducer units
14 in turn in conventional manner to collect the data in this way.
The reason for using sayfourtransducer units spaced along the ship is to obtain a measure of the peak stress which will occur at a position varying along the length of the ship. A simple
curve fitting algorithm applied to the four
measurements of each sampling cycle will provide
an estimate of the peak stress. Accordingly one thousand peak stress measurements will be obtained each second and the data may be stored over a two minute interval so that the last one hundred and twenty thousand measurements are continuously stored.
The data processor 10 is programmed to operate upon statistical information, effectively to provide a prnbabflity or distribution function and then to calculate the probability of a certain danger stress level (or series of levels) being exceeded. The calculated probability or probabilities are continuously displayed on a visual
display device 18. In addition, the data processor
may be connected to an audible alarm device to
trigger an audible alarm when the danger stress
level, or a particular one of the series of levels, has
a certain probability of being exceeded, considered
unsafe. At least the display device 18 and alarm
20 can be installed on the bridge of the ship so that the officer in charge will be warned when it is necessary for him to reduce stresses by reducing speed or even take more drastic action such as preparing to abandon ship.
Claims (3)
1. Apparatus for monitoring stresses in a structure comprising at least one strain transducer providing a signal representing the stress in part ol the structure, data processing means responsive to the signal from the or each transducer over a
period of time to determine in accordance with a predetermined probability function or functions the probability of a predetermined stress level being exceeded, and means for providing an indication of the probability thus determined.
2. Apparatus according to claim 1 wherein the means for providing an indication provide in respect of at least one predetermined stress level a digital or analogue read-out of the probability of that level being exceeded.
3. Apparatus according to claim 1 or 2 wherein the means for providing an indication comprise an alarm device providing an alarm signal when the probability of a predetermined stress level being exceeded exceeds a predetermined probability value.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8106954A GB2094476A (en) | 1981-03-05 | 1981-03-05 | Stress monitoring apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8106954A GB2094476A (en) | 1981-03-05 | 1981-03-05 | Stress monitoring apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
GB2094476A true GB2094476A (en) | 1982-09-15 |
Family
ID=10520169
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8106954A Withdrawn GB2094476A (en) | 1981-03-05 | 1981-03-05 | Stress monitoring apparatus |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2094476A (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0166850A2 (en) * | 1984-02-13 | 1986-01-08 | Telefunken Systemtechnik Gmbh | Process for determining the dynamic loading of a ship |
US4566336A (en) * | 1983-06-27 | 1986-01-28 | Canadian Patents & Development Ltd. Societe Canadienne Des Brevets Et D'exploitation Limited | Navigational aid alerting system |
DE3712651A1 (en) * | 1986-12-03 | 1988-06-16 | Iveco Fiat | Method and device for inspecting the state of the rollers and counter-rollers during the simultaneous rolling of a number of annular surfaces of a rotating workpiece |
US4928959A (en) * | 1988-12-16 | 1990-05-29 | Osteo-Dyne, Inc. | Method and device for providing active exercise treatment for a patient suffering from a bone disorder |
EP0454890A1 (en) * | 1990-05-04 | 1991-11-06 | VVG Befestigungstechnik Beteiligungs-GmbH | Control device for blind rivet setting tools |
GB2290872A (en) * | 1994-06-30 | 1996-01-10 | Caterpillar Inc | Predictive fault detection system |
DE102008028301A1 (en) * | 2008-06-13 | 2011-02-24 | Siemens Aktiengesellschaft | Method for monitoring position of ship hull, involves supplying signals from sensors arranged in ship hull to loading computer that is provided for controlling loading and unloading of ship |
CN111695198A (en) * | 2020-06-03 | 2020-09-22 | 重庆交通大学 | Automatic sensing and early warning system for stress characteristics of ship lock floating mooring column |
CN115265857A (en) * | 2022-06-14 | 2022-11-01 | 上海船舶电子设备研究所(中国船舶重工集团公司第七二六研究所) | Circular tube transducer prestress monitoring method and system based on stress testing system |
-
1981
- 1981-03-05 GB GB8106954A patent/GB2094476A/en not_active Withdrawn
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4566336A (en) * | 1983-06-27 | 1986-01-28 | Canadian Patents & Development Ltd. Societe Canadienne Des Brevets Et D'exploitation Limited | Navigational aid alerting system |
EP0166850A2 (en) * | 1984-02-13 | 1986-01-08 | Telefunken Systemtechnik Gmbh | Process for determining the dynamic loading of a ship |
EP0166850A3 (en) * | 1984-02-13 | 1988-01-27 | Telefunken Systemtechnik Gmbh | Process for determining the dynamic loading of a ship |
DE3712651A1 (en) * | 1986-12-03 | 1988-06-16 | Iveco Fiat | Method and device for inspecting the state of the rollers and counter-rollers during the simultaneous rolling of a number of annular surfaces of a rotating workpiece |
US4928959A (en) * | 1988-12-16 | 1990-05-29 | Osteo-Dyne, Inc. | Method and device for providing active exercise treatment for a patient suffering from a bone disorder |
EP0454890A1 (en) * | 1990-05-04 | 1991-11-06 | VVG Befestigungstechnik Beteiligungs-GmbH | Control device for blind rivet setting tools |
GB2290872A (en) * | 1994-06-30 | 1996-01-10 | Caterpillar Inc | Predictive fault detection system |
GB2290872B (en) * | 1994-06-30 | 1998-07-08 | Caterpillar Inc | Method and apparatus for indicating a fault condition |
DE102008028301A1 (en) * | 2008-06-13 | 2011-02-24 | Siemens Aktiengesellschaft | Method for monitoring position of ship hull, involves supplying signals from sensors arranged in ship hull to loading computer that is provided for controlling loading and unloading of ship |
CN111695198A (en) * | 2020-06-03 | 2020-09-22 | 重庆交通大学 | Automatic sensing and early warning system for stress characteristics of ship lock floating mooring column |
CN111695198B (en) * | 2020-06-03 | 2023-03-24 | 重庆交通大学 | Automatic sensing and early warning system for stress characteristics of ship lock floating mooring column |
CN115265857A (en) * | 2022-06-14 | 2022-11-01 | 上海船舶电子设备研究所(中国船舶重工集团公司第七二六研究所) | Circular tube transducer prestress monitoring method and system based on stress testing system |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA1127287A (en) | Technique for the detection of flat wheels on railroad cars by acoustical measuring means | |
US4585341A (en) | Wind shear detection | |
GB2094476A (en) | Stress monitoring apparatus | |
US3810081A (en) | Submerged chain angle measurement | |
US20220044545A1 (en) | Air-sea buoy monitoring system towards mid-latitude ocean | |
CN111695198B (en) | Automatic sensing and early warning system for stress characteristics of ship lock floating mooring column | |
EP1877747A1 (en) | A system for ice load monitoring | |
CN115352598A (en) | Method and system for calculating actual load tonnage of overhead-sweeping ship | |
CN216350246U (en) | Corrosion monitoring and early warning system of offshore wind power equipment | |
KR101876185B1 (en) | Learning method on recent data considering external effect in early alarm system, and system using thereof | |
KR101549236B1 (en) | Ship hull strength monitoring system | |
JP7128724B2 (en) | Wave height calculation method | |
JP2934564B2 (en) | Wave characteristic extraction device | |
Baker et al. | Reliability Analysis as a Tool in the Design of Fixed Offshore Platforms. | |
JPH0228116B2 (en) | ||
JP3897398B2 (en) | Measuring method of wave forcing force considering bay water vibration. | |
JPS6486942A (en) | Image processing apparatus | |
JP4253767B2 (en) | Ship passage detection device, program and method thereof | |
GB2123240A (en) | Wind shear detection by laser doppler velocimetry | |
JPS6229231A (en) | Water-surface data transmission processing method and water-surface data collection equipment | |
CN114779163B (en) | Underwater sound detection, identification and obstacle avoidance method and system based on wave glider | |
CN115424475B (en) | Device and system applied to intelligent shipping data acquisition | |
Schwab et al. | Intercomparison of wave measurements obtained from a NOMAD buoy and from a Waverider buoy in Lake Erie | |
GB2171208A (en) | Apparatus for analysing sailboat performance | |
JPH02223816A (en) | Multi-function type wave height meter |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |