This study reviewed types and dynamic behavior characteristics of shock-absorbing materials used in spent nuclear fuel transport containers. Among various shock-absorbing materials, wood, honeycomb, and foam materials were the most commonly used. Redwood and balsa wood are sustainable materials with excellent energy absorption properties and natural decomposition, but vulnerable to temperature and humidity. Although honeycomb materials have better mechanical strength than other materials, they only support unidirectional loads. Urethane foam and Fenosol foam materials have lower mechanical strength and lower shock absorption than others, but have higher lightness and fire resistance. They also allow users to control density and produce them. Due to their isotropic characteristics and ease of increasing or decreasing strength by adjusting density, foam materials are better for design and manufacturability than others. Shock-absorbing materials show more complex behavior characteristics than general steel materials. For shock absorption, large deformations are considered up to sections that greatly exceed the elastic region, inevitably increasing the complexity of behavior simulation. During design, to accurately simulate large deformation behavior, it is important to select an appropriate analysis property card and determine major influencing factors. An analysis-based review was additionally conducted for property cards typically applied to foam materials.

In this study, based on directed energy deposition (DED) technology, one of the additive manufacturing technologies, a porous material fabricated by mixing various aluminum alloys and foaming agent was manufactured. First, the foaming agent formed pores inside the deposited materials and differences in foaming characteristics were observed depending on the type of aluminum. Also, the foaming characteristics according to the laser power, which is a representative process variable, were analyzed. As a result, a closed-cell porous material with a maximum porosity at a laser power of 1,100 W was manufactured. Results of the compression test showed that the porous material made by the pores generated therein collapses to absorb energy, and the internal pores disappear to become high density. Therefore, Young’s modulus and yield stress were reduced by the pores inside the sample of pure aluminum and Al6063. However, it was found that the specific energy absorption, which is an advantage of the foamed materials, increased compared to non-porous materials. The findings of this study confirmed that it was possible to manufacture DED-applied foam materials using aluminum powder and a foaming agent.

A fixing frame applied with Foam Cored CFRP Sandwich Composite (FCCSC) that replaces SAPH440 steel used in the fixing frame for hydrogen storage was designed, and its structural safety was evaluated. In the design of the fixing frame, FCCSC was implemented by PMI foam core, a Bakelite mount, and Carbon Fiber Reinforced Plastics (CFRP) using woven carbon fiber prepreg. Unlike the steel fixing frame, the FCCSC-applied fixing frame had a cross-section of hollow-rectangular, and its validity was confirmed through finite element analysis. Structural analysis of the designed FCCSCapplied fixing frame and steel fixing frame was performed. Under the extreme load condition of 9G acceleration, the steel fixing frame showed the lowest safety factor of 1.14 based on the yield strength in the opposite direction of gravity. On the other hand, the FCCSC-applied fixing frame showed a safety factor of 7.6 at the maximum principal stress and 3.15 at the shear stress. Through this result of structural analysis, it was verified that the FCCSC-applied fixing frame, which was 25.8% lighter than the steel fixing frame, was 1.8 times safer.