ASE B4 Structural Analysis & Damage Repair flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Unibody construction

Vehicle construction in which body panels, floor pan, and frame rails are welded into one stressed unit that absorbs and distributes collision energy. Also called unitized construction.

Body-over-frame construction

Construction using a separate heavy steel frame that carries the load, with a body bolted on top. Frame rails can be straightened or replaced independently of body panels.

High-strength steel

Steel grades such as HSLA and dual-phase with yield strengths well above mild steel. OEM repair manuals identify them because heat and sectioning rules differ from mild steel.

Martensitic boron steel

Ultra-high-strength steel, often above 1,000 MPa, used in door intrusion beams and B-pillars. Most OEMs prohibit heat and sectioning, so the part is replaced instead.

Magnet test

A quick check that separates steel from aluminum body panels: a magnet clings to steel but not to aluminum or plastic. Material is confirmed before repair methods are chosen.

Structural member

A part that carries vehicle loads and collision forces, such as frame rails, rocker panels, strut towers, aprons, and floor reinforcements. Repair follows OEM structural procedures.

Datum plane

An imaginary horizontal reference plane established by the manufacturer from which underbody height measurements are taken. All height readings in a dimension chart reference it.

Centerline

An imaginary vertical plane running front to back through the middle of the vehicle. Symmetry checks compare left and right measurements about this line.

Control points

Specific holes or locations on the underbody identified by the OEM with published dimensions. Measuring them shows whether the structure is within tolerance.

Tram gauge

A manual measuring tool with interchangeable pointed tips used to compare diagonal and point-to-point distances. It is inexpensive but requires a dimension chart.

Three-dimensional measuring

A computerized system using targets or probes to compare vehicle points to OEM data in length, width, and height. It gives the most complete picture of structural movement.

Diamond damage

Damage in which one side of the vehicle is pushed rearward relative to the other, so the underbody forms a parallelogram. It is identified by unequal diagonal measurements.

Mash damage

Damage in which a section of the structure is shortened by a direct hit, such as a front rail pushed rearward. It appears as a shorter-than-specification length measurement.

Pull direction

Straightening pulls are applied opposite the direction of the impact force. The anchor and pull are set so the damaged area returns to its original position.

Overpull

Pulling slightly beyond the specified dimension and then releasing to allow springback. The amount permitted is set by the OEM procedure and the structure's elasticity.

Heat restrictions on UHSS

Most OEMs prohibit heating ultra-high-strength steel above a low limit or at all, because heat destroys its strength. These parts are replaced rather than heat-straightened.

Sectioning

Replacing a damaged portion of a panel by cutting at an OEM-approved location and joining a new piece. Sectioning is prohibited in crush zones, on UHSS, and near suspension mounts.

Backing sleeve

An insert placed inside a sectioned hollow member to support a butt joint. Its length, material, and attachment method must match the OEM sectioning procedure.

Frame straightening

Restoring a body-over-frame chassis with a frame machine and hydraulic pulls. The frame is anchored, measured against OEM dimensions, and pulled until within tolerance.

Spot weld removal

Drilling or cutting out factory spot welds with a spot-weld cutter, drill, or belt sander. Only the weld is cut so the base metal remaining on the vehicle is preserved.

Weld-through primer

A zinc-rich coating applied to mating surfaces before welding. It protects the joint from corrosion between panels while allowing current to pass for spot or plug welds.

Panel gap gauge

A tool used to check and set uniform gaps around doors, hoods, and trunk lids. Gaps are set to OEM specification, commonly about 4 to 5 mm.

Cavity wax

A corrosion-inhibiting coating sprayed inside hollow structural sections after repair. It restores factory protection disturbed by welding, cutting, or sectioning.

Rivet bonding

A joining method combining structural adhesive with rivets or self-piercing rivets. The adhesive carries load while the rivets hold alignment until the adhesive cures.

SRS sensor precautions

Do not weld, heat, or strike near airbag sensors, and do not route welding current through them. The battery is disconnected per OEM procedure before structural work nearby.

GMAW shielding gas

For mild and high-strength steel, a common mix is 75 percent argon and 25 percent CO2. Pure CO2 is also used but gives harsher arcs and more spatter.

ER70S-6 filler

A common GMAW wire for automotive steel with good wetting and deoxidation. Filler must match the base metal and OEM specification, especially on high-strength steel.

Squeeze-type resistance spot welding

STRSW equipment passes current through clamped electrode tips to create a factory-style spot weld. It is the OEM-preferred method for many structural joints.

Plug weld hole size

A hole drilled or punched in the top panel for a plug weld, commonly about 5/16 inch (8 mm). The weld fills the hole and fuses both panels.

Heat-affected zone

The area of base metal next to a weld that is changed by heat but not melted. It can soften or harden, so weld spacing and placement follow OEM rules.

Aluminum GMAW

Aluminum is welded with 100 percent argon shielding gas, a push gun angle, and a dedicated wire feeder and gun to prevent steel contamination. Filler is usually 4043 or 5356.

Self-piercing rivet

A rivet that punches through and interlocks the top panel into the lower one without a pre-drilled hole. It requires access to both sides and OEM-specified tooling.