Civil Engineering Reference
In-Depth Information
to produce custom blanks, where strong, lightweight materials are placed where
they are needed, while utilizing more formable steels in other areas, thus allowing
for a relatively strong and easily formable part. However, this process can be time-
consuming, costly and can result in reduced part accuracy because of all the extra
manufacturing steps and associates required to prepare the blanks.
1.3 Limitations of Current Technologies
The goal of any manufacturing engineer is to produce quality parts as efficiently
and cost-effectively as possible. For many common engineering metals, this can
be accomplished rather easily, however, it has proven challenging with some of
the stronger, more lightweight metals which are being incorporated into today's
designs. These materials, such as high-strength aluminum-, steel-, magnesium-,
copper-, and titanium-based alloys, all possess high strength-to-weight ratios, but
their limited formability makes them impractical for use in many real-world appli-
cations that require complex part geometries. The main downfall in using these
materials to make complicated shapes is the fact that, with current technology, the
forming capability is insufficient, such that the forming process is extremely time-
consuming and some very complex shapes may not even be able to be formed at
all. In this case, numerous simpler parts must first be formed and then attached
using screws, rivets, or welds, which can significantly increase the overall cost and
useable lifecycle of the products.
High-production costs and poor part quality issues can result from attaching
smaller, simpler parts together, making the disadvantages of using these materials
outweigh their great strength-to-weight characteristics. To this end, formability-
enhancing techniques are used to increase the overall efficiency of the manufactur-
ing process, thus increasing the applicability of these materials and allowing more
complex part geometries to be formed from single blanks rather than attaching many
smaller components together. Formability-enhancing techniques must be devised
and employed on current manufacturing methods to make them more applicable
for forming lightweight metals. Experts say that extensive research, which couples
materials and manufacturing engineering, is the key toward further developing light-
weight engineering [
19
,
20
]. Not only do novel manufacturing techniques need to
be created and proven, but computer-aided engineering (CAE), analytical modeling,
and simulations of these novel processes must be further developed in order to gain
industry acceptance for a specific formability-enhancing technique.
1.4 Plastic Deformation of Metals
Plastic deformation can be classified as permanent reshaping of a metal. In plastic
deformation by slip, dislocations move through the crystal structure of the metal,
breaking, and reforming metallic bonds. Dislocation motion (i.e., deformation) can
