Installation of hydro-protection resistor strain gages and strain gauge transducers.
Installation of strain gauges for general use.
Mounting gages according to their type, and test conditions produced label or welded to the test surface, and by embedding into the test elements of settable materials such as fiberglass.
Sticker general purpose strain gages designed to measure strain of ± 1 % in the climatic temperature range is produced in most of the cold-curing adhesives, nitrocellulose and cyanoacrylate groups. Sticker temperature-compensated strain gages used in the range of 175 ... 475 K, is thermosetting adhesives fed- nolnoy, vinifleksovoy and furan groups, depending on the material and dimensions of the working temperature range. When installing the high- strain gages, operating at temperatures T - 525 ... 575 K, apply silicone binder.
Technology sticker adhesives of all these groups, except for express cyanoacrylate adhesives group, is reduced to the following operations:
- Immediately prior to the installation location of strain gages sticker cleaned of dust and wipe the swab moistened with ethyl alcohol or ether to remove water condensate;
- On the prepared sites of the object of measurement ¹ 3-8 kolinsky brush a thin layer of adhesive, while the same layer is applied to the contact surface of the base of the strain gauge and dried for 10-15 minutes;
- By the second strain gage is applied , a thicker layer of adhesive and incubated for 2-3 minutes until thickening;
- Orient the strain gage on the markers of risk at the plant and tightly pressed against the surface;
- The strain gauge is placed on top of the fluoroplastic or triacetate film , after which a finger or a rubber roller , moving along the gage , remove the excess glue ;
- Pasted gage stand 1-2 hours under pressure ( load ) at the rate of about 0.2 ... 0.3 MPa;
- After removal of the release pressure gage film and dried to complete removal of excess solvent , usually within 1-2 days. Objective evidence of the completion of drying is to stabilize the resistance to its isolation from the test surface ( for conductive materials);
- If the sticker is made of strain gages thermosetting adhesive after drying produce a normal heat treatment on the recommended adhesive for this regime , during heat treatment, strain gages should be pressurized to 0.3 ... 0.5 MPa;
- After drying or polymerization glued strain gauges are checked by quality labels and the correct position of the strain gauges relative marking ticks, check the straightness of the filament lattice also , the presence of an electrical circuit, resistance and insulation level of strain gauges on the targeted surface.
Sticker gages cyanoacrylate adhesive superglue express -30 can be performed after priming the base paper by a strain gauge glue and then drying or polymerization. Strain gages with the base film does not require a primer. A polyethylene tube with glue removed from the refrigerator and kept at a temperature of 295 ± 10 K for 15 ± 20 minutes. Then, the ampoule is pierced a hole diameter of about 0.3 mm and the contact surface of the substrate a thin layer strain gauge adhesive. Immediately after applying the glue as precisely gage placed on the marked area and kept under pressure for 1 min. Subsequent drying is carried out at normal temperature and humidity of 50 ... 80 % within 6 hours.
In all cases, you should use the guidance material detailing the technology stickers in some assembly glue. General technological requirements for the label of strain gauges are given in the descriptions.
Simultaneously with the label of strain gauges mounted and glued mounting pads made of an insulating material with embedded into it conduits for podpayki strain gages and wiring harness. Pads glued close to the cross- sawn-off shotgun fundamentals of strain gauges on the part of the terminal conductors. Mounting pads protect the continuity of the strain gages for installation and eliminate the possibility of short circuits in the measurements.
The level of insulation glued strain gauges must not be less than 50 100 ... Mom , if measurements are made under normal conditions and expected deformation does not exceed 1%.