Technology Overview

Structural Health Monitoring / Management

CVM™ Overview

CVM™ offers a novel method for in-situ, real-time monitoring of crack initiation and/or propagation. CVM™ is a measure of the differential pressure between fine galleries containing a low vacuum alternating with galleries at atmosphere in a simple manifold. If no flaw is present, the vacuum will remain at a stable level. If a flaw develops, air will flow through the passage created from the atmosphere to the vacuum galleries. Sensors may either take the form of self-adhesive polymer sensors or may form part of the component. A transducer measures the fluid flow between the galleries.

CVM™ has been developed for use in both a laboratory environment or on operating equipment. The laboratory testing equipment has rapidly gained acceptance in testing facilities within the aviation industry; often used to control a fatigue testing program due to its proven reliability and built-in fail-safe properties. A portable unit is available to allow monitoring of components in operating equipment where access to critical components is difficult, time consuming and costly.

This product is capable of being integrated with an aircraft to provide an in-flight structural health monitoring system (SHM). The In-flight structural health monitoring system developed using the CVM™ technology is able to continuously monitor the development of any cracks in predefined areas on an aircraft that are deemed to have a high risk of crack formation. The implementation of this technology will reduce the cost of mandatory structural integrity maintenance inspections, increase aircraft performance, and provide an increase in the safety of air travel.

In-flight SHM using CVM™ system produced by SMS will consist of a number of different types of sensors placed at strategic locations throughout an aircraft that are linked to onboard instrumentation to detect and report on the initiation and growth of cracks.

CVM™ Competitive Advantages

The fundamental simplicity of the CVM™ technology provides a unique set of competitive advantages and great flexibility in the design and application of structural monitoring systems. CVM™ systems:

  • are simple to install, lightweight and inert with long term durability;
  • can be implemented in a range of sensor types and configurations to address structural fatigue and structural integrity health monitoring requirements;
  • installed in hard to access areas can be periodically inspected via a remote access point in a matter of minutes, enabling a major reduction in maintenance inspection costs and improvements in aircraft operational availability;
  • fluidic sensors are made from radar transparent materials that do not generate electromagnetic or acoustic emissions;
  • can detect and monitor cracks by direct measurement of pressure changes avoiding the complicated processing of complex sensor outputs currently used in existing inspection techniques;
CVM™ offers a novel method for in-situ, real-time monitoring of crack initiation and/or propagation. CVM™ is a measure of the differential pressure between fine galleries containing a low vacuum alternating with galleries at atmosphere in a simple manifold. If no flaw is present, the vacuum will remain at a stable level. If a flaw develops, air will flow through the passage created from the atmosphere to the vacuum galleries. Sensors may either take the form of self-adhesive polymer sensors or may form part of the component. A transducer measures the fluid flow between the galleries.

Critical Success Factors

A generic set of critical success factors for structural integrity monitoring systems are:

1. System Configuration:

  • Easily installed
  • Easily maintained
  • Low Weight

2. Monitoring Requirements:

  • Periodic / Continuous
  • Can be operated with and without loads

3. Assessment Interpretability:

  • Understandable by structural test personnel
  • Minimal off-line processing
  • Indicates location of damage

4. Reliability:

  • All damage over threshold detected
  • No false positive calls
  • Not effected by aircraft environment
CVM™ offers a novel method for in-situ, real-time monitoring of crack initiation and/or propagation. CVM™ is a measure of the differential pressure between fine galleries containing a low vacuum alternating with galleries at atmosphere in a simple manifold. If no flaw is present, the vacuum will remain at a stable level. If a flaw develops, air will flow through the passage created from the atmosphere to the vacuum galleries. Sensors may either take the form of self-adhesive polymer sensors or may form part of the component. A transducer measures the fluid flow between the galleries.

Critical Success Factors

A generic set of critical success factors for structural integrity monitoring systems are:
Figure 1: A schematic of a simple CVM sensor.
Figure 2: CVM system installed on an intact component.
Figure 3: CVM system installed on a damaged component.

Over 30 patents held globally – jurisdictions include USA, EU, China and Brazil, protecting all aspects and components of CVM™

14 patents pending on new inventions

Commitment to aggressively defend existing patents, if applicable, and pursue new inventions

CVM™ technology uses the principle that a vacuum maintained within a small volume is extremely sensitive to leakage. Essentially the CVM™ technology provides a measure of the differential pressure between alternating channels containing air at a partial vacuum pressure and channels containing air at atmospheric channels in a simple manifold.

These channels are on the under surface of a sensor that is applied to a surface on a critical structure that requires monitoring. If a crack begins to develop underneath the sensor, air will flow from the channels at atmospheric pressure, through the passage created by the crack, to the vacuum channels. A transducer is used to measure the air flow between the channels and provide feedback to the software management system, which in turn reports on the development of the crack. The sensitivity of the sensor is governed by the gallery spacing and the rate of air flow gives an indication of the size of the developing flaw.

SMS has conducted extensive research to prove the principle of the technology and has developed a number of sensor types and associated testing systems. To date the current CVM™ system consists of the following four main components:

  • A sensor that is applied to the area requiring testing or inspection
  • A vacuum source to control and apply a partial vacuum to the sensor
  • A differential pressure flow meter device with output options that interface with the control systems and
  • Can be operated with and without loads

The existing generation of the technology is suitable for static or periodic monitoring (for grounded aircraft). To create an in-flight continuous monitoring system SMS will need to create a host of new sensor technologies and in-flight instrumentation.

Commercial and military aircraft operations have a significant amount of MRO expenditure allocated to maintaining the integrity of airframe. Current NDI technologies whilst effective in treating small local areas are slow, labour intensive and time consuming. Internal structure is difficult and costly to access and often left until a major overhaul such as a heavy structural Check.

During the operational life of a commercial aircraft, it will be subject to many scheduled and urgent maintenance inspections for possible fatigue cracking. The customary inspection tools and processes cannot effectively improve the turn around time to return the aircraft to operational service.

SMS has recognised that building a Structural Health Monitoring System into an airframe at manufacture is possible to comprehensively achieve a number of benefits:

  • Weight reduction in new airframe designs to improve payload and fuel ratios by removing redundant engineering.
  • Real time structural health monitoring of airframe integrity to predict and schedule maintenance on a more cost effect basis.
  • As a retrofit to existing aircraft to minimise costly invasive processes at scheduled intervals
  • To permit airframe inspections to be carried out in field situations with confidence for rapid turn around to mission readiness.
  • To reduce repetitious labour and make better use of MRO resources.
  • To provide a reliable and repeatable means of assessing airframe integrity and building a database of airframe performance for MRO analysis.

Comparative Vacuum Monitoring: A New Method of In-Situ Real-Time Crack Detection and Monitoring

Comparative Vacuum Monitoring (CVM) offers a novel method for in-situ, real-time monitoring of crack initiation and/or propagation. CVM is a measure of the differential pressure between fine galleries containing a low vacuum alternating with galleries at atmosphere in a simple manifold. If no flaw is present, the vacuum will remain at a stable level. If a flaw develops, air will flow through the passage created from the atmosphere to the vacuum galleries. Sensors may either take the form of self-adhesive polymer “pads” or may form part of the component. A transducer measures the fluid flow between the galleries.

CVM™ offers a novel method for in-situ, real-time monitoring of crack initiation and/or propagation. CVM™ is a measure of the differential pressure between fine galleries containing a low vacuum alternating with galleries at atmosphere in a simple manifold. If no flaw is present, the vacuum will remain at a stable level. If a flaw develops, air will flow through the passage created from the atmosphere to the vacuum galleries. Sensors may either take the form of self-adhesive polymer sensors or may form part of the component. A transducer measures the fluid flow between the galleries.

Critical Success Factors

A generic set of critical success factors for structural integrity monitoring systems are:

1. System Configuration:

  • Easily installed
  • Easily maintained
  • Low Weight

2. Monitoring Requirements:

  • Periodic / Continuous
  • Can be operated with and without loads

3. Assessment Interpretability:

  • Understandable by structural test personnel
  • Minimal off-line processing
  • Indicates location of damage

4. Reliability:

  • All damage over threshold detected
  • No false positive calls
  • Not effected by aircraft environment
CVM™ offers a novel method for in-situ, real-time monitoring of crack initiation and/or propagation. CVM™ is a measure of the differential pressure between fine galleries containing a low vacuum alternating with galleries at atmosphere in a simple manifold. If no flaw is present, the vacuum will remain at a stable level. If a flaw develops, air will flow through the passage created from the atmosphere to the vacuum galleries. Sensors may either take the form of self-adhesive polymer sensors or may form part of the component. A transducer measures the fluid flow between the galleries.

Critical Success Factors

A generic set of critical success factors for structural integrity monitoring systems are:
Figure 1: A schematic of a simple CVM sensor.
Figure 2: CVM system installed on an intact component.
Figure 3: CVM system installed on a damaged component.

Over 30 patents held globally – jurisdictions include USA, EU, China and Brazil, protecting all aspects and components of CVM™

14 patents pending on new inventions

Commitment to aggressively defend existing patents, if applicable, and pursue new inventions

CVM™ technology uses the principle that a vacuum maintained within a small volume is extremely sensitive to leakage. Essentially the CVM™ technology provides a measure of the differential pressure between alternating channels containing air at a partial vacuum pressure and channels containing air at atmospheric channels in a simple manifold.

These channels are on the under surface of a sensor that is applied to a surface on a critical structure that requires monitoring. If a crack begins to develop underneath the sensor, air will flow from the channels at atmospheric pressure, through the passage created by the crack, to the vacuum channels. A transducer is used to measure the air flow between the channels and provide feedback to the software management system, which in turn reports on the development of the crack. The sensitivity of the sensor is governed by the gallery spacing and the rate of air flow gives an indication of the size of the developing flaw.

SMS has conducted extensive research to prove the principle of the technology and has developed a number of sensor types and associated testing systems. To date the current CVM™ system consists of the following four main components:

  • A sensor that is applied to the area requiring testing or inspection
  • A vacuum source to control and apply a partial vacuum to the sensor
  • A differential pressure flow meter device with output options that interface with the control systems and
  • Can be operated with and without loads

The existing generation of the technology is suitable for static or periodic monitoring (for grounded aircraft). To create an in-flight continuous monitoring system SMS will need to create a host of new sensor technologies and in-flight instrumentation.

Commercial and military aircraft operations have a significant amount of MRO expenditure allocated to maintaining the integrity of airframe. Current NDI technologies whilst effective in treating small local areas are slow, labour intensive and time consuming. Internal structure is difficult and costly to access and often left until a major overhaul such as a heavy structural Check.

During the operational life of a commercial aircraft, it will be subject to many scheduled and urgent maintenance inspections for possible fatigue cracking. The customary inspection tools and processes cannot effectively improve the turn around time to return the aircraft to operational service.

SMS has recognised that building a Structural Health Monitoring System into an airframe at manufacture is possible to comprehensively achieve a number of benefits:

  • Weight reduction in new airframe designs to improve payload and fuel ratios by removing redundant engineering.
  • Real time structural health monitoring of airframe integrity to predict and schedule maintenance on a more cost effect basis.
  • As a retrofit to existing aircraft to minimise costly invasive processes at scheduled intervals
  • To permit airframe inspections to be carried out in field situations with confidence for rapid turn around to mission readiness.
  • To reduce repetitious labour and make better use of MRO resources.
  • To provide a reliable and repeatable means of assessing airframe integrity and building a database of airframe performance for MRO analysis.

Comparative Vacuum Monitoring: A New Method of In-Situ Real-Time Crack Detection and Monitoring

Comparative Vacuum Monitoring (CVM) offers a novel method for in-situ, real-time monitoring of crack initiation and/or propagation. CVM is a measure of the differential pressure between fine galleries containing a low vacuum alternating with galleries at atmosphere in a simple manifold. If no flaw is present, the vacuum will remain at a stable level. If a flaw develops, air will flow through the passage created from the atmosphere to the vacuum galleries. Sensors may either take the form of self-adhesive polymer “pads” or may form part of the component. A transducer measures the fluid flow between the galleries.

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