Fiber Makes Inroads in Stress/Strain Measurement

Anne L. Fischer, Senior Editor

Demand for increasingly sophisticated measurement tools is on the rise in oil and gas as well as in civil-structure industries, among others. Traditional test equipment has included strain gauges and load cells, but fiber optic technologies recently have been gaining in acceptance and use, according to the World Stress/Strain Measurement Equipment Markets study released by Frost & Sullivan of Palo Alto, Calif., a global growth consulting company.

The study segments the market into conventional and fiber optic equipment. The fiber optic technologies discussed include fiber Bragg gratings, Brillouin scattering, and Fabry-Perot and Rayleigh scattering methods. Currently, fiber Bragg gratings make up about 70 percent of the total fiber optic market, with Fabry-Perot and Rayleigh scattering following behind. Senior research analyst Sujan Sami expects the Rayleigh scattering method to increase in use and revenues in the future.

One impediment to growth in use of fiber optic tools is the familiarity that the industry has with conventional tools, which have been used for more than 60 years. “More than 100 companies make strain gauges,” Sami noted, “whereas only a few players are available for fiber optic.” This is changing, however, as he sees many of the conventional tool manufacturers moving into fiber optics.

Another deterrent is cost. Conventional tools cost one-third what fiber optics cost; however, the research notes that the reality is that the many advantages of optical fiber will drive up demand, enabling vendors to deliver lower-cost solutions. Sami added that a major challenge is to educate users about the many advantages and the cost-effectiveness of fiber optic instruments.

Advantages of fiber optic tools include ease of use, flexibility and remote sensing capability. Traditional strain gauges, for example, whether benchtop or handheld, are heavy and inflexible and can be placed only sporadically throughout a structure to measure stress and strain. On the other hand, hundreds of sensors can be placed within a flexible fiber, allowing measurements at consistent intervals.

Fiber optic sensing also can be used at great depths under the sea or ground, and it is impervious to water and climate damage as well as to electromagnetic interference. For these reasons, fiber is ideal for remote sensing applications. The market, however, is slow to trust the reliability of these new techniques, and Sami estimates that it will be five to seven years before it shifts to fiber optic methods.

The report indicates that in 2006, the total stress/strain measurement equipment market generated revenues of $3.24 billion at a growth rate of 3.6 percent. Only 2.9 percent of this came from fiber optic market segments. The market is expected to grow at a compound annual growth rate of approximately 5 percent through 2013. The fiber optic segment is expected to grow at a compound annual growth rate of about 11 percent from 2006 to 2013.