Additive manufacturing, also known as three-dimensional printing, is well known for the design and manufacturing of advanced materials with desirable properties for different applications. In particular, functionally graded materials with varying properties depending on the microscopic length scales are capable of eliminating discontinuity and stress concentration at the interface of the material. Up to now, several methods such as additive manufacturing have been developed for manufacturing the functionally graded materials depending on the intended applications. Additive manufacturing is more advantageous in that it allows for design optimization and waste minimization. Furthermore, the development of computing technology has also enabled design and material simulation before the actual manufacturing process to validate the its properties and feasibility for supporting the intended application.
Presently, digital image correlation technique is widely preferred for experimental validation of the functionally graded materials. It allows measurements of large strains and sensitivity depending on the specimen being analyzed and involves the use of high precision camera suitable for analysis of highly complex geometries. As such, to improve on the results, accurate validation methods for finite element solutions is highly desirable.
Dr. Maedeh Amirpour, Professor Simon Bickerton and Professor Brian Mace from the University of Auckland in collaboration with Dr. Emilio Calius from Callaghan Innovation and Dr. Raj Das from RMIT University recently investigated the quasi-static transverse deformation of three-dimensional printed polymeric functionally graded plates. Fundamentally, they used a three-dimensional digital image correlation method, that involved generation of displacement by tracking the geometric motion on the surface of the specimen, to measure the deflection of the polymeric functionally graded materials. Their research work is currently published in the research journal, Composite Structures.
Briefly, the research team designed and fabricated the polymeric plates by a three-dimensional printing technique. The manufactured graded materials generally obeyed the property distribution throughout the length of the material. Furthermore, graded solid elements showing continuous property distribution at various Gauss points were analyzed in a finite element software. To validate their methodology, they compared the obtained results with those for graded finite element numerical solutions.
The authors observed that the out of plane deflection for the nonlinear functionally graded plates was relatively higher than that obtained for nonlinear plates. This was attributed to the high gradient distribution of the materials. However, the experimental results and the finite element solutions were consistent with each other with the correlation factors ranging from 85% to 90%. Furthermore, non-symmetrical contours for the functionally graded plates was noted with the effect being more pronounced in the linear high stiffness ratio.
In summary, Maedeh Amirpour and her colleagues successfully presented a novel three-dimensional digital image correlation method for investigating and validating the deformation of 3D-printed polymeric functionally graded plates. Since the method can be used to create tailored deformation patterns throughout the gradient, it can be used to analyze the non-uniform deformation shape of complex structures. Altogether, the study provides vital information that will pave way for better representation of the out of plane deformation by eliminating the effects of the noise and vibration.
Amirpour, M., Bickerton, S., Calius, E., Das, R., & Mace, B. (2019). Numerical and experimental study on deformation of 3D-printed polymeric functionally graded plates: 3D-Digital Image Correlation approach. Composite Structures, 211, 481-489.Go To Composite Structures