4D structures for the short-time building of emergency shelters

The increasing number of internal displaced people due to conflicts or natural disasters over the years represents the need to create structural solutions for first emergency shelter, which are currently supplied in tarpaulin and structures improvised by the locals. Innovative technologies like 4D printing could present an alternative, being possible to develop 3D structures with smart materials that react with environmental stimulus, such as water, light, heat and others. Unlike 3D printing, which is static, the factor ‘time’ adds a dimension to the 4D, making the structures self-assembling, multifunctional or self-repairing. Given this, the aim of this paper is to present research for the application of 4D-printed structures, for crises, to speed up and ease the assembly process, replacing the structures currently used with one that integrates the emergency kit. It also presents a review on emergency shelters, as well as on 3D and 4D printing processes, clarifying its definition and introducing a case study demonstrative of the process, by printing with shape memory filaments, specifically poly lactic acid and shape memory polymers. A concept was developed and validated, evaluating the possibility of applying 4D printing process in the development of structures that are easy to transport and assemble in emergencies, using the beneficial characteristics of shape memory polymer material. Therefore, the simulation of the concept and the improvement of material properties in terms of specific strength and toughness, which can be achieved using composite materials, are indicated as future recommendations. Moreover, the concept must be evaluated from a structural point of view.