Correction to: The influence of stiffener geometry on flexural properties of 3D-printed polylactic acid (PLA) beams

Gebrehiwot, Silas; Espinosa-Leal, Leonardo; Eickhof, J. N.; Rechenberg, L.

doi:10.1007/s40964-020-00149-z

Cited by 4 publications

(5 citation statements)

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“…It is expected that the pattern sample which has the highest central deflection to have the highest deflection to length ratio has the lowest flexural rigidity. 64 In this case, the trihexagonal sample exhibited the highest deflection to length ratio of 0.26, which is in agreement with the characteristics concluded in Figure 14 as well. However, instead of the gyroid pattern being the sample with the least deflection to length ratio, the cubic pattern sample showed the least ratio of 0.8, thereby based on the deflection to length ratio making this sample the better choice among the rest due to the highest flexural rigidity of the beam.…”

Section: Resultssupporting

confidence: 89%

“…Consequently, within the elastic zone, thorough investigation of the Central Load-Deflection performance, it would be feasible to analyze the flexural rigidity that directly determines the rigidity of the beam subjected to bending stresses. 64 Regarding the beam geometrical characteristics, a comparison in the Load-Deflection performance is made to distinguish the beam stiffener which possesses superior flexural characteristics. The curvature of an Euler-Bernoulli beam subjected to a pure bending moment M caused by the central load P is identified by 65,66…”

Section: Theoretical Analysis Of Beam Under Flexural Loadmentioning

confidence: 99%

“…Central deflection formulations are presented in equation (7), where several potential functions of central deflection can be applied to solve them. 71 The Euler-Bernoulli time-dependent equation of beam bending in the y-axis direction is shown as 64 qA…”

Section: Theoretical Analysis Of Beam Under Flexural Loadmentioning

confidence: 99%

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Mechanical performance of three-dimensional printed sandwich composite with a high-flexible core

Ahmed

Alnajjar

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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This paper aims to investigate experimentally and using finite element analysis the performance of using three-dimensional printing technology to produce a composite sandwich panel that is made of the high-flexible core as well as with high stiffness upper and lower surfaces made of a glass fiber reinforced composite filament. There are many advantages of using sandwich structures in many applications, especially the aerospace field, where the high stiffness to strength and the lightweight is the most preferred in such applications. The conventional manufacturing methods that are used to produce sandwich panels are limited to particular core geometry, whereas manufacturing a composite core is not possible by these traditional production methods. So by using additive manufacturing technology, it becomes more applicable to design a combination of different geometries and materials to achieve properties that have never been made before, especially combining flexibility and high energy absorption keeping high strength to failure. A central deflection to a length of 0.26 is observed within the elastic zone, a remarkable ratio in beams that reflects the three-dimensional printed sandwich beams’ capability with a highly flexible core to absorb energy that would open doors for many industrial applications that is attributed to the lowest flexural rigidity (167E-3Pa · m4) of the sandwich by using the TriHex infill pattern. In contrast, the Gyroid infill structure could afford the highest central load (0.264 kN). At the peak load applied on the sandwich beam, a maximum error of 5.4% is estimated by finite element analysis lower than the experimental values.

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Section: Resultssupporting

confidence: 89%

Section: Theoretical Analysis Of Beam Under Flexural Loadmentioning

confidence: 99%

See 1 more Smart Citation

Mechanical performance of three-dimensional printed sandwich composite with a high-flexible core

Ahmed

Alnajjar

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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“…The flexural rigidity EI is generally involved in beams with various geometrical characteristics brought on by various stiffening capabilities. A thorough analysis of the load-deflection performance within the elastic zone is therefore required, and analysis of the flexural stiffness, which directly affects the rigidity of the beam subjected to bending loads, would be possible [50,51]. In order to identify the beam stiffener with the best flexural characteristics given the geometrical properties of the beam, the comparison of the performance of the load-deflection variables is made.…”

Section: Analytics For a Beam Under Bending Loadmentioning

confidence: 99%

Investigating the Impact of Inclusions on the Behavior of 3D-Printed Composite Sandwich Beams

2022

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In this study, a finite element model was developed, and a detailed analysis was carried out to investigate the impact of inclusions on the mechanical characteristics of a 3D-printed composite sandwich beam that could initiate when printing the layers, especially during the transition period between the dissimilar material that would affect the interfacial strength between the layers that would cause the failure of the 3D-printed beams. Several parameters that could influence the failure mechanism have been investigated. These parameters include the location, size, material properties, and interfacial location of the inclusion along the beam. Linear elastic behavior has been adopted in this finite element analysis using the ‘Ansys’ simulation tool to model and analyze the defective beams compared to the intact ones. The effects of defects related to maximum shear stress (MSS) and maximum principal stress (MAPS) were investigated. The results revealed that the midpoint of the composite is highly stressed (31.373 MPa), and the concentration of stress decreases outward as we move toward the edges of the composite to reach zero at the edges. For the intact case, the deformation was maximum at the center of the composite (4.9298 mm) and zero at both ends of the beam. The MSS was highest at the center (23.284 MPa) and decreased gradually as we approached the ends on both sides to reach 0.19388 MPa at the edges, making the shear stress distribution symmetrical. The MAPS is constant throughout the beam apart from the lower face of the beam and is maximum at the face material. The MSS is high at the endpoints where we have the support reactions, which may weaken the entire material’s mechanical properties. It was also observed that along the load L3 (applied at 2 mm from the top face of the beam), the MSS values decrease as we move away from the center, which may cause failure at the end of the beam. It was also noticed that the presence of inclusions along load L2 (applied at 2 mm from the bottom face of the beam) initially causes a sharp decrease in MAPS while moving away from the center, at 25 mm, while the MAPS increases as it approaches the end of the beam. This increase in the MAPS near the beam support might be due to the reaction of the fixed support, which tends to oppose the applied flexural load and hence increases the principal stress capability of the beam.

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“…Nowadays, FE software provides possibilities to define mechanical behaviours of materials that contribute to accurate material models in computational analyses. Our previous work on the influence of stiffener geometry on flexural properties of additive manufactured beams used the COMSOL structural mechanics for modelling and analyses (Silas et al 2020). COMSOL has suitable features to define viscoelastic material models, such as generalised Maxwell, Burgers and standard linear solids (SLS).…”

Section: Viscoelastic Materials Model On Comsolmentioning

confidence: 99%

Characterising the linear viscoelastic behaviour of an injection moulding grade polypropylene polymer

Gebrehiwot

Espinosa-Leal

2021

Mech Time-Depend Mater

Self Cite

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The linear viscoelastic behaviour of an injection moulding grade polypropylene is studied using theoretical and computational methods. Polypropylene has a variety of engineering applications as a component. However, it commonly exhibits viscoelastic deformations. This paper analyses the creep and recovery responses of the BJ368MO polypropylene copolymer using the Burgers and generalised Maxwell models. Within the linear viscoelastic regime, an experimental creep strain at $20\ \text{MPa}$ 20 MPa is used to determine the rheological constants of the models. These constants (springs and dashpots) are determined using a nonlinear least-squares curve fitting of the experimental creep. Then they are used to predict the creep and recovery responses of the polymer at three different stresses, $10\ \text{MPa}$ 10 MPa , $12.5\ \text{MPa}$ 12.5 MPa and $15\ \text{MPa}$ 15 MPa . The experiments are made using tensile specimens designed according to the ASTM D638-14standard. The theoretical evaluations are made using the creep and recovery equations derived from their constitutive. Whereas COMSOL Multiphysics software is used during the finite element (FE) analyses. The results of the theoretical and FE calculations are verified using creep and recovery experiments. Based on the validation analyses, both viscoelastic models showed lower deviations from the experimental results when a computational approach is used. In addition, the viscoelastic models are compared by evaluating the residuals of the creep and recovery strain predictions. The theoretical analyses showed better predictions at $12.5\ \text{MPa}$ 12.5 MPa and $15\ \text{MPa}$ 15 MPa stresses when the generalised Maxwell model is used. However, the improvements are attributed to the recovery predictions. When FE is used, the Burgers model showed lower mean absolute percentage errors (MAPEs) in all creep and recovery predictions. The model has a minimum of 6.37% error at the $10\ \text{MPa}$ 10 MPa stress and a maximum of 8.23% error at the $15\ \text{MPa}$ 15 MPa . By comparison, the generalised Maxwell model showed a minimum of 9.24% error at $12.5\ \text{MPa}$ 12.5 MPa and a maximum of 12.8% error at $15\ \text{MPa}$ 15 MPa stresses. The novelty of this paper is on predicting the creep and recovery behaviour of the polymer using the FE and theoretical approaches in the linear viscoelastic regime. The findings suggest that the FE analyses using the Burgers viscoelastic material model provide better predictions, with all calculated errors falling below 10%.

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Correction to: The influence of stiffener geometry on flexural properties of 3D-printed polylactic acid (PLA) beams

Cited by 4 publications

References 0 publications

Mechanical performance of three-dimensional printed sandwich composite with a high-flexible core

Mechanical performance of three-dimensional printed sandwich composite with a high-flexible core

Investigating the Impact of Inclusions on the Behavior of 3D-Printed Composite Sandwich Beams

Characterising the linear viscoelastic behaviour of an injection moulding grade polypropylene polymer

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