WO2019002619A1

WO2019002619A1 - System for the non-destructive health monitoring of fiber-reinforced structures such as fiber-reinforced hollow parts

Info

Publication number: WO2019002619A1
Application number: PCT/EP2018/067773
Authority: WO
Inventors: Mathias MÜGGENBURG
Original assignee: Kurotec - Kts Kunststofftechnik Gmbh
Priority date: 2017-06-30
Filing date: 2018-07-02
Publication date: 2019-01-03
Also published as: DE202017003463U1; EP3659346A1

Abstract

The invention relates to a system for the non-destructive structural health monitoring of a structure and/or hollow part made of a fiber-reinforced plastic (fiber-reinforced composite), said system comprising at least a combination of a sensor, which is form-locked to the fiber-reinforced plastic structure and/or hollow part to be monitored, and a radio unit, connected to the sensor, for transmitting the data acquired by the sensor.

Description

Nondestructive condition monitoring system for fiber reinforced structures, such as fiber reinforced hollow bodies

Technical area

The present invention relates to a system for nondestructive testing of a sample using a combination of sensors and radio units that allow continuous monitoring to provide data obtained by nondestructive testing. In accordance therewith, the present invention also provides a method for non-destructive testing of a sample using a combination of sensors and radio units that provide continuous monitoring to provide data obtained by nondestructive testing.

State of the art

Fiber-reinforced hollow bodies, such as pipes or reactors, are widely used in the chemical industry. Frequently, the materials to be transported therein or the reactions to be carried out therein are such that continuous structure monitoring is necessary to ensure that no leaks, etc. occur in which toxic or otherwise hazardous substances or mixtures escape. Manual monitoring processes are labor-intensive, time-consuming and costly, since the systems to be monitored often have to be shut down and partially emptied or measuring devices have to be installed (expensive conventional monitoring methods are, for example, external visual monitoring, monitoring by external light irradiation, endoscopic camera inspection, X-ray monitoring). Only then can the test be carried out, which often can not be non-destructive, since samples may have to be removed from a system and then analyzed. Such monitoring and test procedures also make it difficult to reliably estimate during operation when a component of a system needs to be replaced, since the necessary structural integrity is no longer guaranteed. This uncertainty leads to high costs because, on the one hand, parts are replaced earlier than necessary (to ensure plant safety) and, on the other hand, manual checks take place at shorter intervals.

Non-destructive techniques have been developed in the area of structural monitoring (hereinafter also structural health monitoring / SHM), for example in the field of aircraft construction. Non-destructive testing makes it possible to detect different types and sizes of aircraft Defects and above that the determination of the material properties. Conventional nondestructive testing techniques for samples, such as fiber reinforced plastics, include ultrasonic and thermographic testing. For example, in ultrasonic pulse non-destructive testing, a pulse passes through the sample and is reflected off the opposite surface of the sample. Defects within the sample reflect, absorb or dissipate the pulse such that a pulse echo from the opposite sample surface of the sample is reduced. Such monitoring, also known as Structural Health Monitoring (SHM), is important in the area of fiber-reinforced carbon structures. Such fiber composite materials are materials which consist of reinforcing fibers which are embedded in a plastic matrix. The problem with such structures are the damage reaction and damage monitoring. In this context, SHM methods are known in which measurement signals are detected with separately used elements. Such a signal detection takes place both at dormant structures as well as structures in use.

Object of the invention

Due to the relevance of such structure monitoring, for example, in pipes and reactors made of fiber composite plastics which are widely used in the chemical industry, improved systems for SHM are in demand. Frequently, highly corrosive and / or toxic compositions are transported and reacted in such pipes and reactors, so that accurate structural integrity monitoring is important to avoid damage. A particular challenge in this case is the heterogeneity of the fiber composite material (for example produced with resin transfer molding from multi-axial lay-up or dry winding and / or wet semi-automated hand winding).

Therefore, it is the object of the present invention to provide a system and method for structure monitoring, which non-destructively monitors the structural integrity in such systems or on such components and transmits the data determined thereby to a central data processing unit, so that an automatic and continuous detection and evaluation possible becomes.

Brief description of the invention

The inventive system for non-destructive condition monitoring therefore comprises the components defined in claim 1. Preferred embodiments are specified in the dependent claims. The skilled person will be informed on the basis of the following description. It should be understood that the present invention is not limited to the specific combinations of features described, but will be apparent to those skilled in the art further combinations and embodiments, which are included and protected here.

Detailed description of the invention

The system according to the invention comprises at least one building, such as a hollow body (pipe, pipe, reactor) or the like, which is made of a fiber-reinforced plastic material. This is the part to be monitored. This hollow body is further equipped with a sensor which is positively connected to the monitored structure made of fiber composite plastic.

This sensor may for example be a PWAS sensor (piezoelectric wafer active sensor). This sensor is suitable for acquiring structural integrity data and is based on PWAS guided waves in the multilayer composite. It is advantageous that unilateral accessibility for structural monitoring is completely sufficient. Such sensors are according to the invention positively connected to the component to be monitored, and this can already be done in the construction of the component. However, a retrofit of already installed components is possible. In this case, a lamination and encapsulation with epoxy materials has proven to be suitable.

The sensor can then detect quantitative data, such as a measured increase in attenuation and drop in phase velocity, by using appropriate pulses (eg, Lamb waves). Such effects correlate with the conventional indicators of global fatigue damage, inter-fiber cracking density and resulting stiffness degradation. Such structural disturbances as a result of static and dynamic (over) loading lead to microcracks that absorb, for example, a pressurized or heated medium (such as, for example, aggressive media stored, reacted or transported in such structures and hollow bodies.) This leads to degradation phenomena. which ultimately lead to destruction (bursting, leakage, etc.) It has been shown that the scattering at interfaces increases with the increase in the crack density, which leads to an increase in the attenuation of the shaft the calculation of dispersion curves with the global matrix method analyzed, whereby the stiffness degradation of individual layers with an already existing model from the observed crack densities is determined. Scanning with guided Lamb waves allows the characterization of local defects. The method is suitable for nondestructively tracking the effect of these defects on the fatigue mechanisms during cyclic loading during operation. In addition, data can be generated that can be used to evaluate the degeneration, the static load and the dynamic load (in embodiments, this evaluation can be done virtually in real time).

The data evaluation then takes place, for example, on the basis of the method of acoustic emission analysis (SEA), which is based on the detection of elastic waves which are emitted by failure events such as inter-fiber breakage, fiber breakage or delamination in the fiber composite component. A significant advantage of the system according to the invention is to be seen in the immediate detection of damage events, which locally have a spontaneous release of deformation energy result. The challenge to deduce the type and severity of the damage from the amplitude and frequency of the acoustic signals could be successfully overcome according to the invention by the use of acoustic (preferably piezoelectric) sensors. A sensor form that is preferably used for this purpose is that the actuator and sensor work in one element.

The data acquisition in such an actuator / sensor unit takes place in the context of the resonance. Due to the anisotropy of the fiber composite material is therefore preferably not evaluated with a constant frequency but the system preferably always calibrates to the frequency at which the highest amplitude is present. This is ensured by the bidirectionality of the actuator / sensor unit. This allows extremely accurate measurement data acquisition.

At the same time, this sensor is connected to a controller and / or radio unit likewise provided on the structure to be monitored. These components are used for data transfer to a central data acquisition and data evaluation system. At the same time, a trigger threshold can already be taken into account so that, for example, when a certain level is exceeded, automated messages, optionally via an intermediate data processing and storage unit, are transmitted to terminals (tablet / smartphone, etc.). The unit of sensor and radio unit is preferably designed so that a long-term use is possible. For this purpose, this unit can be equipped with a battery for a sufficiently long power supply. This way, several years of operation can be secured. The central data acquisition system can be a cloud-based system or even an application server, so that a strong spatial separation is possible and, for example, optimal computer capacities can be exploited. Optionally, so-called gateway devices may be interposed so as to transmit the data of a plurality of sensors completely to the data acquisition and data evaluation unit. Of course, the system according to the invention may comprise a large number of such sensors, so that it is possible to monitor a larger system. In the case of large (extensive) systems to be monitored, where it may not be possible to ensure that the data can be safely transmitted from the individual sensors to a central unit (because the distance is too long for a secure wireless transmission), individual areas can The system can be equipped with individual receivers (gateway installations) so that even large-scale plants can be safely monitored. This creates contiguous or overlapping areas in which the individual sensors can communicate with the respective gateway installations, so that all data obtained can be transmitted securely. Such systems are called according to the invention LoRaWAN systems, so long ranks wide area network systems. For example, LoRaWAN radio data can be converted into a 3G / 4G network. This allows forwarding of such (sensitive) data with a high level of security (such as AES 128).

Such monitoring systems thus comprise a plurality of sensors, each equipped with a wireless unit for wireless data transmission and positively connected to the structures / hollow bodies to be monitored. Furthermore, such a system, depending on the size of the system at least one gateway installation for receiving the data (and forwarding this to a central data acquisition and data processing unit). The data of the multiple sensor units can be processed centrally. Since the sensors continuously acquire the data and transmit it in a suitable manner continuously, so the central data acquisition and data processing unit can continuously process the received data to filter out from the raw data necessary for the structure monitoring information. The data processing programs to be used in this context are familiar to the person skilled in the art.

The advantage of the SHM method according to the invention and thus of the system according to the invention over conventional methods is that they can in principle always provide clues about the functionality of a component and / or continuously track the generation of defects in real time, so that an alarm is sent via suitable control of the evaluation - tion function can be ensured. Depending on the method of data evaluation can also be describe the load condition continuously (in the following also CMS, "condition monitoring system). Due to the continuous structure monitoring, such a system during operation of a plant so in time to point to emerging vulnerabilities, so that maintenance and repairs can be carried out targeted. Since the monitoring takes place continuously during operation, undesired style service lives can be avoided. This system can also be designed in such a way that, for example, warnings are automatically transmitted to the person responsible for a particular part of the installation in the case of weak points or problem areas that are emerging, so that then the necessary further steps can be initiated without delay. The system can also automatically suggest the steps to be initiated in embodiments and, for example, make material orders, etc.

In this way, monitoring can take place continuously without switching off the system to be monitored, without the need for personnel, since the sensors and radio units independently carry out the data generation, data transmission and data acquisition and evaluation. In accordance with application-selected presets, the system can then continuously communicate status reports based on the received data so that necessary maintenance or repair work is scheduled in time and in accordance with, for example, normal shutdowns (for cleaning operations or when switching to others Reactions / materials) can be performed. Thus, in particular, the time required for such maintenance and repairs, since they can be planned better reduced. In addition, the continuous monitoring of the system continuously records and evaluates the maintenance-relevant structural data so that it is often possible to predict in advance how long to carry out maintenance and repair work. This also simplifies the workflow in such systems.

Moreover, the use of the system according to the invention, which comprises a contactless data transmission, can avoid complicated wiring, which is both labor-intensive and expensive. By using well-known sensor techniques, even large-scale systems can be continuously monitored, since the radio modules used ensure reliable data transmission over radio links of several kilometers.

It has been shown that components and entire systems made of fiber-reinforced plastic materials can be reliably monitored with a system described above. Both single-layer and multilayer fiber composite plastics can be used (ie to be monitored). The type of plastic and the type of reinforcing fiber are not critical. The system according to the invention has proved to be particularly suitable for glass fiber reinforced plastic components. In this case, structures / hollow body with different wall thicknesses and diameters can be easily monitored, for example, tubes, as they are typically used in chlorine chemistry, with wall thicknesses of a few millimeters and diameters of a few inches.

The system according to the invention is suitable for monitoring critical points of a system / component, although a complete system can also be monitored. All that is required is for a sufficient number of sensors to be mounted on the system. With the above-disclosed as preferred PWAS sensors (SHM with Lamb waves), it is sufficient in a system to distribute the sensors so that the distance between the individual sensors in the range of 1 to 5 meters, preferably 1 to 3 meters. This ensures a complete continuous structure monitoring (SHM and CMS).

With regard to the adjustment of the sensors, it has been shown that the best results are obtained if a calibration takes place after installation. This calibration aims to find the measuring frequency at which the received signal is strongest, ie the amplitude is maximized. This is typically the case if the measurement frequency corresponds to the resonance case. As a result, sufficiently strong and easily interpretable signals can be obtained, so that the structure monitoring can be operated with excellent reliability.

As already stated, the data evaluation takes place on the basis of the transmitted raw data in a central data processing unit using analytical software for data processing. Due to the continuous and automatic data acquisition and data evaluation, the system can be configured such that the determined state information is automatically transmitted to the intended recipient (maintenance personnel, but also data storage / data storage), for example by wireless transmission to end user devices (smartphone / tablet / laptop, etc.). ). Ultimately, this provides a condition monitoring system that continuously, non-destructively generates state data over a long period of time, automatically and wirelessly transmits it and a data acquisition and evaluation unit, and then provides the state information and possibly action suggestions (maintenance intervals, concrete maintenance or repair work). This creates a communicating system in which a component to be monitored is transmitted independently and continuously by the sensor and radio unit to status data. The data obtained in this context, for example, automated alerts in case of loss (or impending loss, the particular threshhold can be customized) of structural integrity, by email, SMS and other typical electronic forms of communication.

The above explanations, which are based on the configuration of the system according to the invention, are readily transferable to the person skilled in the art for the method according to the invention. This comprises in particular the attachment of the above-described sensor or radio unit, preferably by lamination or encapsulation, for example with epoxy. The transmission of signals from the sensor and also the transmission, for example, to mobile devices are ensured according to the invention by known in principle protocols. Here, depending on the application situation, the system and also the procedure can be easily adapted to the specific circumstances. This is a further advantage of the present invention since, in principle, a modular system is provided which is easily adaptable while at the same time enabling simple and reliable condition monitoring.

Claims

claims

1. A system for non-destructive structure monitoring of a structure and / or hollow body made of a fiber-reinforced plastic (fiber composite plastic), comprising at least one combination of a sensor which is positively connected to the monitored structure and / or hollow body made of fiber composite plastic, as well as a connected to the sensor Radio unit for transmitting the data obtained by the sensor.

2. A method for non-destructive structure monitoring of a structure and / or hollow body made of a fiber-reinforced plastic (fiber composite plastic), comprising the transmission of data obtained by a sensor which is positively connected to the structure to be monitored and / or hollow body made of fiber composite, obtained by a data with the Sensor connected radio unit.

The system of claim 1 or the method of claim 2, wherein the sensor is a PWAS sensor.

4. A system or method according to any one of claims 1 to 3, wherein the radio unit is a short-range radio unit according to ETSI EN 300 328 V1.7.1.

5. System or method according to one of the preceding claims, wherein the hollow body is a reactor or tube of a glass fiber reinforced plastic.

6. System or method according to one of the preceding claims, wherein the PWAS sensor acts as a sensor and actuator and the data is generated by Lamb wave pulses.

A system or method according to any one of the preceding claims, comprising a plurality of combinations of sensor and radio unit.

8. System or method according to one of the preceding claims, wherein a plurality of structures and / or hollow bodies are monitored simultaneously.

9. The system or method of claim 8, wherein the plurality of structures and / or hollow body part of a plant, for example in the chemical industry.

10. System or method according to one of the preceding claims, further comprising at least one gateway installation, to which first the data of a defined group are transmitted to sensors.

1 1. System or method according to one of the preceding claims, further comprising a data acquisition unit, suitable for receiving and processing the data generated by the at least one sensor (with or without the interposition of a gateway installation).

12. The system or method of claim 1 1, wherein the data acquisition unit is configured such that the derived from the data processing structure information is automatically transmitted to mobile devices

The system or method of any one of claims 10 to 12, wherein multiple gateway installations are provided to provide contiguous or overlapping surveillance areas.

14. System or method according to one of the preceding claims, wherein the combination of sensor and radio unit is designed so that it can be active for a period of at least 60 months without external power supply.

15. System or method according to one of the preceding claims, wherein the sensor, preferably the PWAS sensor is positively connected by lamination with the hollow body.

16. System or method according to one of the preceding claims, wherein the data evaluation for SHM and / or CMS is suitable.

17. System or method according to one of the preceding claims, further comprising means for web-based location-independent visualization of the data evaluation.

18. System or method according to one of the preceding claims, for use in the context of an on-line predicative maintenance.