## 1 Introduction  
Additive manufacturing (AM), mostly referred to as 3D printing, is known as the family of processes used to manufacture parts by accumulating thin layers of material over the previously deposited one. The pattern of deposition follows 3D CAD data available through slicing of a digital model. Each layer is deposited on x-y plane, whereas layer upon layer deposition in z direction determines the height of the 3D printed object. Application areas of AM are automotive sector [1], aerospace applications [2], marine, oil and gas sector, heavy machinery, consumer sector [3], biomedical field [4], architectural miniature models, civil construction works [5, 6], food industry [7], and repair works of degraded parts [8]. The variety in AM processes is created by processes designed to use a variety of materials, at different physical conditions, and during the time of manufacture [9]. In 1991, three AM commercial machines, based on unlike processes, were introduced: Fused Deposition Modeling (FDM) by Stratasys, Solid Ground Curing (SGC) by Cubital, and Laminated object manufacturing (LOM) by Helisys [10]. Among all of the AM machines, FDM is third in top of the line machines, for its characteristics of producing functional parts of complex geometry, using various thermoplastic materials safely within a closed environment [11]. FDM process involves a layer-by-layer deposition of material extruded through a nozzle. During extrusion, the nozzle is following a predefined path, created according to the geometry of each layer. The commonly used material is plastic or wax, supplied in the form of filament, heated through heating coils. Heating coils are attached to the nozzle such that the material can be maintained at 0.5 \({}^{\circ}\)C above the melting temperature before extrusion. Extruded material fuse and solidify immediately over the previously deposited layer. Thus, a layer-by-layer deposition of material is carried out on a heated platform, which allows minimum distortion in part. After completion of a single layer, space is provided according to the diameter of the nozzle for the next layer, as shown in Figure 1.  
During slicing operation for FDM printing, supports are added to eliminate risk of collapsing the material at areas, freely hanging and extending outwards, beyond the main geometry of the model. Break away type of support structures can be easily removed after the completion of the building process [12]. Along with the support structure, infill material is specified during slicing operation. Infill is the amount of material used to fill inside the cavity of the model, specified, in percentage, of cross sectional areas, ranging from 100% infill to 0% infill material to build the model [13]. Cellular structures are ordered materials that are constructed by the repetition of a unit cell [14]. The promising properties of these materials are their lightweight construction, higher strength and energy absorption with minimum material consumption. The principles that drive the properties of cellular solids depends on the material, the joining pattern of cell through the edge, face, or vertices, and the relative density of the structure [15; 16; 17]. Cellular structures can be segregated as natural occurring or artificially produced by humans, which include structures made up of cells with open or closed boundaries, randomly distributed or periodic, and 2D or 3D in structure [11]. Nature has provided an unlimited variety of these structures around and within us. Most common naturally occurring cellular structures are wood [17], bone structure [18], corals and cork [15], toucan beak [19], and many more. Humans get the inspiration from the variety of design and use of these structures, by nature, and adopt them in their construction. Lattice structure, initially defined by [PERSON] and [PERSON] as three dimensional cellular structure having cell walls, follows random orientation in space [15].