دانلود کتاب Novel cellular materials for energy absorption applications

Cellular materials such as metal foams are porous, lightweight structures that exhibit good
energy absorption properties. They have been used for many years in various applications
including energy absorption. Traditional cellular structures do not have consistent pore sizes
and their behaviors and properties such as failure mechanisms and energy absorption are not
always same even within the same batch. This is a major obstacle for their applications in
critical areas where consistency is required. With the popularity of additive manufacturing,
new interest has garnered around fabricating metal foams using this technology. It is necessary
to study the possibility of designing cellular structures with additive manufacturing and their
energy absorbing behavior before any sort of commercialization for critical applications is
contemplated. The primary hypothesis of this senior project is to prove that energy absorbing
cellular materials can be designed. Designing in this context is much like how a car can be
designed to carry a certain number of passengers. To prove this hypothesis, the paper shows
that the geometry is a key factor that affects energy absorption and that is possible to design
the geometry in order to obtain certain behaviors and properties as desired. Much like designing
a car, it requires technical expertise, ingenuity, experience and learning curve for designing
cellular structures. It is simple to come with a design, but not so much when the design in
constrained by stringent requirements for energy absorption and failure behaviors. The scope
was limited to the study of metal foams such as the ones made from aluminum and titanium.
The primary interest has been academic rather than finding ways to commercialize it. The study
has been carried out using simulation and experimental verification has been suggested for
future work. Nevertheless, the numerical or simulation results show that energy absorbing
cellular structures can be designed that exhibit good energy absorption comparable to
traditional metal foams but perhaps with better consistency and failure behaviors. The specific
energy absorption was found to be 18 kJ/kg for aluminum metal foams and 23 kJ/kg for
titanium metal foams. The average crushing force has been observed to be around 70 kN for
aluminum and around 190 kN for titanium. These values are within the acceptable range for
most traditional metal foams under similar conditions as simulated in this paper.