MER2 1 4 : Strength of Materials Strain Gage Preparation Department - PowerPoint PPT Presentation

MER2 1 4 : Strength of Materials Strain Gage Preparation Department of Mechanical Engineering Union College Schenectady, NY Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 1 Union College Schenectady, NY

Strain Gage Preparation • Surface Preparation • Strain Gage Bonding • Lead Wire Attachment • Evaluation of Gage Performance • Specimen Evaluation Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 2 Union College Schenectady, NY

Surface Preparation Avoid the Follow ing • Touching the surface with the fingers • Wiping back and forth or reusing swabs or sponges • Dragging contaminants into the cleaned area from the uncleaned boundary of that area • Allowing a cleaning solution to evaporate from the surface • Allowing a partially prepared surface to sit between steps in the preparation process or a prepared surface to sit before bonding Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 3 Union College Schenectady, NY

Surface Preparation Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 4 Union College Schenectady, NY

Surface Preparation • Solvent Degreasing – Spray solvent onto specimen – Use gauze pad to wipe specime • Surface Abrading – Place M-Prep Conditioner A on Specimen – Wet-lap surface – 320 grit SC paper • When surface is bright – Wipe surface dry Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 5 Union College Schenectady, NY

Layout Lines • The gage will be placed near the center of the specimen • Using a scale and pencil, scribe line along the length of the specimen • Apply Conditioner A and clean surface with cotton- tipped applacator • Apply Neutralizer to surface and clean with gauze pad Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 6 Union College Schenectady, NY

Strain Gage Bonding • Remove gage from package, DO NOT Touch • Place gage on clean surface (acetate envelope) • Pick gage up using cellophane tape • Align gage on specimen Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 7 Union College Schenectady, NY

Bonding Gage to Specim en • Peal gage off specimen • Apply catalyst sparingly on gage • Apply two drops of adhesive to base of gage • Apply pressure for one minute. Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 8 Union College Schenectady, NY

Solder Lead W ires to Gage • Take six feet of six wire ribbon • Separate and strip the six wires on both ends • Twist and tin all wires • Drop a bead of solder on gage terminals • Solder wires to terminals Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 9 Union College Schenectady, NY

Preparation Completion • Use masking tape to stabilize lead wires • Check resistance of gage to insure proper installation Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 1 0 Union College Schenectady, NY

Strain Gage Recording Ronald B. Bucinell, Ph.D., P.E. Departm ent of Mechanical Engineering 1 1 Union College Schenectady, NY