Literature Review - Finite Element Analysis for Satellite Structures - page 7

• The need for disassembly
• Cost (materials, parts, tooling, manufacturing labor, verification)
• Schedule (availability of materials and parts; manufacturing time)
• Quality assurance and reliability
1.3.3.1 Fastening
Types of fasteners are countless, but it can be divided into broad categories. Most
consist of a load-bearing shaft and a head or nut on each end. This type includes
threaded fasteners and rivets. Mechanical fasteners are readily available and often
inexpensive. They have standard sizes and thread geometry. They can also be
installed in almost any facility without expensive tools or process controls. They
add damping to a structure. However, they have a big weight and loss of stiffness is
hard to be avoided. Premature failure in brittle materials can appear due to stress
concentration introduced at fastener locations. Most fasteners can be easily dis-
assembled, and are good for dissimilar materials. They are suitable for most
structures and mechanisms made of ductile materials.
1.3.3.2 Welding
Welding is the process of joining two materials—usually with a filler material—by
applying intense heat and sometimes pressure. With the right materials and suit-
able conditions, welding reliably achieves a strong, stiff joint. Often, welding is the
most economical method of attachment, although it is limited to joining similar,
weldable metals. The key disadvantages of welding are that it is a permanent form
of attachment. It can cause distortions and cracks in some materials especially
aluminum. Welding quality varies with the process, so workmanship must be
developed and tested.
1.3.3.3 Adhesive Bonding
Adhesive bonding is widely used for joining structural parts, particularly for
bonding face sheets to honeycomb, and joining polymer-matrix composites. It is
also used to electrically isolate solar cells from support structure, and separate
dissimilar metals that are susceptible to galvanic corrosion. A key advantage of
adhesive bonding is that loads distribute over the entire joined region instead of
locally at fasteners. As a result, it can often save weight, and the lower stress
concentrations can lead to longer fatigue life. Adhesive can add structural
damping, and join dissimilar materials that cannot be welded. However, it cannot
be disassembled and has limited shelf life. Some adhesives are toxic and require
good ventilation.