77 Chapter 4 Fundamentals of Collision Damage
Copyright Goodheart-Willcox Co., Inc.
Goodheart-Willcox Publisher
Figure 4-43. Notice that the impact was on the right
side. The right bumper mount is collapsed and the left
bumper mount is pulled down.
Goodheart-Willcox Publisher
Figure 4-42. A—This unibody vehicle was hit hard in
the rear. Notice the lack of a quarter panel/rear door
gap. Both rear unirails are collapsed and the quarter
panels are buckled. B—The trunk floor was also
damaged.
Goodheart-Willcox Publisher
Figure 4-44. The force of the falling tree pushed
the front of the roof down and the sides of the roof
in. Notice the position of the right front door window
frame.
A
B
Summary
■ The properties of the metals used in a vehicle will
affect the amount of damage that occurs when the
vehicle is involved in a collision.
■ Different types of metals have different grain
patterns. Grains are formed by the crystalline
pattern of the metal and alloy molecules.
■ Metal with elastic deformation will return to its
original position if the force holding the metal out
of position is removed.
■ If an applied force moves metal beyond its
yield point, it will cause a change in the grain
arrangement in one small area of the metal. This
permanent change in the grain arrangement is
called plastic deformation.
■ A bend is purposely put into the part when the
part is manufactured, while a buckle is caused by
impact force.
■ A bodyline is a styling line in a hood, fender, or
door.
■ Crown is the curvature of a panel. Crown is found
on all outer body sheet metal panels.
■ Force can be defined as any action between two
objects that changes their relative condition as to
motion or rest.
■ Yield point is the minimum amount of force
required to cause a permanent change in grain
arrangement.
■ Longitudinal force is force applied from one end
of a panel.
■ Lateral force is force applied from the side of a
panel.