A Numerical Study on 3D Printed Cementitious Composites Mixes Subjected to Axial Compression

Aptly enabled by recent developments in additive manufacturing technology, the concept of functionally grading some cementitious composites to improve structural compression forms is warranted. In this work, existing concrete models available in Abaqus Finite Element (FE) packages are utilized to simulate the performance of some cementitious composites numerically and apply them to functional grading using the multi-layer approach. If yielding good agreement with the experimental results, two-layer and three-layer models case combinations are developed to study the role of layer position and volume. The optimal and sub-optimal performance of the multi-layer concrete configurations based on compressive strength and sustained strains are assessed. The results of the models suggest that layer volume and position influence the performance of multi-layer concrete. It is observed that when there exists a substantial difference in material strengths between the concrete mixes that make up the various layers of a functionally graded structure, the influence of position and of material volume are significant in a two-layer configuration. In contrast, in a three-layer configuration, layer position is of minimal effect, and volume has a significant effect only if two of the three layers are made from the same material. Thus, a multilayered design approach to compression structures can significantly improve strength and strain performance. Finally, application scenarios on some structural compression forms are shown, and their future trajectory is discussed.

Improved Control Volume Method for Thermoelastic Analysis of Functionally Graded Solids

In this work, an improved control volume finite element method (ICVFEM) is proposed and implemented for thermoelastic analysis in functionally graded materials (FGMs) at steady state. Different from the conventional CVFEM, the sub-control volume used in the proposed method is a circular in the intrinsic coordinate. The advantages of the new integral domain are: (i) the complex integration path can be avoided, (ii) the method is very suitable for many types of elements. High-order shape functions of eight quadrilateral (Q8) elements are used to obtain the unknown variables and their derivatives. Besides, material properties in a functionally graded structure are calculated by the high-order shape functions based on the properties defined at the node. To verify the convergence and accuracy of the proposed method, three numerical examples with analytical solutions are illustrated by using the conventional CVFEM and FEM at the same time.

Time-Dependent Deflection Responses of Porous FGM Structure Including Pattern and Porosity

The transient deflections of the functionally graded structure considering various types of patterns (power-law, sigmoid and exponential) are computed in this paper numerically using a higher-order shear deformation model. Also, the model includes variable distribution of porosity, i.e., the even and the uneven types, through the thickness direction ([Formula: see text]-axis) of the graded panel. The transient deflection data are obtained computationally via a customized computer code prepared in MATLAB in association with Newmark’s constant acceleration-type time-integration technique. The model accuracy is checked by comparing the present time-dependent data with the published transient deflection values and the simulated results (modeled through a commercial package, ANSYS). Further, the effects of several design parameters (aspect ratio, thickness ratio, power exponent, porosity index, type of porosity, geometry and end-support conditions) on the transient deflection responses of the graded structure are computed through the derived numerical model.