PSI - Issue 47

Hachimi Taoufik et al. / Procedia Structural Integrity 47 (2023) 711 – 722 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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fracture mechanism Kinloch et al. (1995), that is to say, to avoid at all costs the brittle (unstable) fracture and to seek the conditions which lead, to the event of rupture, to a ductile fracture where the crack propagates in a stable and controllable way Tyson et al. (2018). 3D printing technology or additive manufacturing is an emerging technique of printing layer by layer of structures with the aid of a CAD (software Computer-aided design. AM technique includes digital light processing (DLP)Tan et al. (2003), Schneider et al. (2020) stereolithography (SLA), Eng et al. (2017), Ubaid et al. (2020), selective laser sintering (SLS), Tan et al. (2003), fused filament fabrication, Bartlett et al. (2015) Verma et al. (2021) Alam et al. (2020). The FFF technique uses a polymeric thermoplastic filament made of PLA (polylactic acid), PE (Polyethylene or polythene), and ABS (acrylonitrile butadiene styrene) Fico et al. (2022). The counter-rotating Pushes it to a heating block into a nozzle, so the head travels along a pre-defined path, for example, G-code, and deposits the materials so that the specimen or the component is being produced layer by layer Pal et al. (2021). Of course, the diffusion and entanglement processes occur at the interfaces of the different deposited strands Yin et al. (2018), which is also a significant factor concerning the final properties. The loading condition of the layer orientation can be pretty impactful Tavallali et al. (2010). For the ±45° printing orientation, it is possible to get mixed mode loading of the interfaces between the stands, significantly influencing the mechanical properties Forster (2015), Rouf et al. (2022). The FEM Finite element method is a numerical method used to solve engineering problems and uses various mathematical techniques. Ashcroft et al. (2018). The name came from subdividing a more significant problem into smaller, more superficial portions known as finite elements; these elements consist of nodes and can be of many different types like triangular and trapezoidal elements Tracey (1971). XFEM method is a numerical method that involves the local enrichment of local elements at all the nodes close to the discontinuity Tianyuan et al.(n.d.), Bybordiani et al. (2021). It uses the concept of the partitioning of unity Fries (2018). The consideration of the finite element method encounters discontinuity, such as singularities, local deformations, fractures, cracks, or complex geometries Paul et al. (2017), Liu et al. (2022). The XFEM tries to achieve the system, allows mesh manipulation, and adjusts the approximate space by incorporating enriched nodes enrichment function across the discontinuity, so there is no need for mesh refinement Fries et al. (2006). XFEM has many advantages, Easy modeling for complicated geometries, crack propagation element by element without improvement, and enhanced element with more degrees of freedom at the fracture surface and crack tips Paul et al. (2017).

Nomenclature a

crack length

t

time

σ w

nominal stress

width of the specimen Poisson's ratio a correction factor stress intensity factor

ν

f(a/w)

KI

Kic

critical stress intensity factor

σt εt

true stress true strain applied load actual area

F a L

specimen length