SAMPE Journal - July/August 2017 - 3

A Note from the Technical Editor

Bonding, Joining and Hybrid Joint Systems
The recent SAMPE Seattle 2017 technical program featured three sessions on
"Bonding and Adhesives Technology." A total of 21 presentations were made
regarding this technology covering preparation, materials and process aspects.
While much of this technology has been founded on the needs within the aerospace
industry for structural joints that often are adhesively bonded, or bolted together
(maybe even both), other industries often require
joining of several structures. The marine industry
Dr. Scott W. Beckwith, FSAMPE
has long been known to require adhesively
SAMPE Journal Technical Editor
bonded joints. The automotive industry, in
swbeckwith@aol.com
shifting to the application of more lightweight
composites, is looking at how to join composites to traditional metal structures.
Aerospace has typically bonded composite laminates to themselves, to metal
structural components and to ceramic materials. Thermoset adhesives typically
are used and the surface preparation methods are often rigid, well-defined and
carefully controlled. However, the cure times often are quite long and not necessarily adaptable to production line
automotive requirements. Riveting, bolted and bonded-bolted joints also are common within the aerospace industry.
Thermoplastic composites typically are "heat welded" together using electrical heating or hot air heating of structures.
Such processes with thermoplastics offer the automotive industry faster potentially "joining times" for assembling
thermoplastic composite parts to each other.
Film adhesives have frequently been used to bond honeycomb core structures to composite laminates (as well as
to metallic sheet materials and foam core structures). These materials typically require freezer storage, removal,
thawing, application and thermal curing which requires time and expense. In many
situations, they are the appropriate bonding and joining method for high performance
aerospace structural applications. However, for the automotive industry, most likely
other methods are preferred.
The science, art and engineering aspects of "bonding and joining" technology has
always involved careful material preparation so that the chemical, mechanical or
combined joint structure achieves maximum structural performance over time. Surface
preparation and joint preparation (machining, drilling, bolt patterns, alignment, etc.)
all must be carefully controlled. Post-processing inspection is also of key importance.
Testing of joints potentially to some predetermined load level may be required to assure long-term durability and
ability to sustain design loads.
The challenge for industries such as the automotive market, is to determine what current bonding and joining
technologies meet their needs as they increase composites use within their vehicles. Automotive structures currently
rely on a significant amount of steel and aluminum metallic support structures based upon decades of experience
with welding, bolting and riveting technology. The term "hybrid joint systems"
is becoming a term more widely heard within that industry. CAMX 2017 will be
looking at how combinations of "bonding, joining and hybrid joint systems" are
being assessed across the automotive industry and other markets where traditional
methods may not satisfy current production and structural requirements. Combining
two or more potentially different materials together while assuring long-term
structural efficiency and durability is an important technology. Non-destructively
inspection (NDI) aspects for confirming joint integrity is an associated technology
area of equal importance. Joints which cannot later be disassembled present a need
for more rigorous NDI methodologies.
SAMPE will be addressing several of the above issues in the future at our conference and educational events. This
area is important to continues aerospace industry interests as well as emerging automotive market use of composites.
SAMPE Journal, Volume 53, No. 4, July/August 2017

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