State different types of extensometer along with their least count.
Answers
Answer:
Usually, the extensometers are classified as contact, non-contact, laser, and video extensometers. However, the working principle of extension-meters depends on its type as well as the application area.
Explanation:
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Explanation:
Definition
An extensometer is a high precision instrument specially designed for geologists or civil engineers to measure the elongation of a material under stress. This instrument is perfect for tensile tests
How does an extensometer work?
Usually, the extensometers are classified as contact, non-contact, laser, and video extensometers.
However, the working principle of extension-meters depends on its type as well as the application area. Encardio-Rite deals with a wide range of extensometers, including magnetic, electrical, mechanical, and soil extensometers. All of these extension-meters have different working principle.
Magnetic Extensometer
The magnetic extensometer system is designed to measure settlement or heave of the soft ground under the influence of loading or unloading due to the construction of embankments, fills, buildings, and structures.
Lateral movement at any level within a soil mass may be assessed by monitoring the location of magnetic targets positioned over a near-horizontal access tube. The lateral ground movement may be in abutments, foundations or embankments, and a consolidation-induced
settlement in embankments and foundations.
Electrical Extensometer
The electrical borehole extensometer incorporates a vibrating wire transducer for measurement of displacement. A groutable reinforced bar anchor (1) is attached to fibreglass (2.a) or AISI 410 stainless steel (2.b) connecting rods of appropriate length, as specified in the design.
Fibreglass connecting rods are supplied from the factory in single lengths. The connecting rods are enclosed inside heavy-duty protective tubing to allow for free movement. The displacement sensor is coupled to the connecting rod using link plate and lock nut.
Mechanical Extensometer
The borehole extensometer measures the extension (displacement) which takes place with time in a borehole or several boring holes in a rock mass. It essentially consists of one or more anchors and a reference plate. The anchor or anchors are set in the same borehole or different boreholes drilled adjacent to the first borehole.
Soil Extensometer
The soil extensometer uses a vibrating wire sensor for monitoring displacement. The system consists of a sensor assembly with flanges that are mounted with adaptors, adjustment unit, sockets and extension rods between two anchors to monitor the horizontal movement of surrounding soil.
The system is enclosed in telescopic PVC tubing with proper ‘O’ ring seals to eliminate friction between the rods and surrounding soil and to prevent any ingress of water.