On the fatigue strength of 3D-printed polylactide (PLA)

Ezeh, O.H.; Susmel, Luca

doi:10.1016/j.prostr.2018.06.007

Cited by 57 publications

(27 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As far as AM PLA is concerned, examination of the state of the art demonstrates that, so far, the scientific community has focused their attention on components 3D‐printed by setting the infill level equal to 100%. Mechanical behaviour and static/fatigue strength of 100% infill AM PLA are influenced by different technological parameters that include: layer thickness, nozzle size, manufacturing orientation, filling rate, feed rate, manufacturing rate, and filling temperature. In this context, it is interesting to observe that much experimental evidence suggests that, as long as objects are 3D‐printed flat on the built plate, the effect of the raster orientation can be neglected with little loss of accuracy .…”

Section: Introductionmentioning

confidence: 99%

Static assessment of plain/notched polylactide (PLA) 3D‐printed with different infill levels: Equivalent homogenised material concept and Theory of Critical Distances

Ahmed

Susmel

2018

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

A novel approach based on the equivalent homogenised material concept and the theory of critical distances is formulated to perform static assessment of plain/notched objects of polylactide (PLA) when this polymer is additively manufactured with different infill levels. The key idea is that the internal net structure resulting from the 3D‐printing process can be modelled by keeping treating the material as linear elastic, continuum, homogenous, and isotropic, with the effect of the internal voids being taken into account in terms of change in mechanical/strength properties. This idea is initially used to assess the detrimental effect of the manufacturing voids on the static strength of the plain (ie, unnotched) material. This is done by addressing this problem in a Kitagawa‐Takahashi setting via the Theory of Critical Distances. Subsequently, this approach is extended to the static assessment of notched components of 3D‐printed PLA; ie, it is used to take into account simultaneously the effect of both manufacturing voids and macroscopic geometrical features. The accuracy and reliability of this design methodology were checked against a large number of experimental data generated by testing, under axial loading, plain specimens, as well as notched samples (including open notches) of PLA. These specimens were manufactured by making the infill level vary in the rage 10% to 90%. This validation exercise allowed us to demonstrate that the proposed approach is highly accurate, returning estimates falling within an error interval of ±20%. This remarkable level of accuracy strongly supports the idea that static assessment of 3D‐printed materials with complex geometries and manufactured with different infill levels can be performed by simply post‐processing conventional linear elastic finite element (FE) solid models, ie, without the need for modelling explicitly the detrimental effect of the manufacturing voids.

show abstract

Section: Introductionmentioning

confidence: 99%

Static assessment of plain/notched polylactide (PLA) 3D‐printed with different infill levels: Equivalent homogenised material concept and Theory of Critical Distances

Ahmed

Susmel

2018

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

show abstract

“…In particular, this log‐log chart was built by plotting the ratio between the maximum stress in the fatigue cycle, σ max , and σ UTS versus the number of cycles to failure, N f . In this diagram, σ max is used to take into account in a very simple and direct way the effect of non‐zero mean stresses …”

Section: Fatigue Strength Of Am Plamentioning

confidence: 99%

“…It is possible to conclude the present section by observing that, as per the statistical re‐analysis, which is summarised in the S‐N diagram of Figure , a reference design fatigue curve (for P S ≥ 90%) suitable for performing the fatigue assessment of AM PLA with infill level equal to 100% can be taken as follows:

k = 5.5,

σ_{MAX} = 0.1 \cdot σ_{UTS} at N_{Ref} = 2 \cdot 10^{6} cycles to failure .

…”

Section: Fatigue Strength Of Am Plamentioning

confidence: 99%

Reference strength values to design against static and fatigue loading polylactide additively manufactured with in‐fill level equal to 100%

Ezeh

Susmel

2019

Mat Design & Process Comms

View full text Add to dashboard Cite

The aim of this paper is to provide a quantitative examination of the state-of-theart knowledge of the static and fatigue behaviour of additively manufactured (AM) polylactide (PLA). To this end, existing literature was reviewed, and a number of data sets were extracted and re-analysed in terms of static strength and standard S-N curves. As long as objects are 3D-printed flat on the build plate, printing direction appears to have little effect on the mechanical behaviour of AM PLA, therefore stress/strain analysis can be performed effectively by simply treating this polymer as a linear-elastic, homogenous, and isotropic material. If static strength cannot be determined experimentally, a conservative reference value of 22 MPa is suggested as being used in situations of practical interest. As far as fatigue is concerned, findings from post-processing reveal that non-zero mean stresses can be modelled by simply using the maximum stress in the cycle. According to the statistical re-analysis discussed in the paper, a reference fatigue curve for the design of AM PLA subjected to uniaxial cyclic loading (for a probability of survival larger than 90%) can be defined by taking the negative inverse slope equal to 5.5 and the endurance limit (at 2·10 6 cycles to failure) equal to 10% of the material ultimate tensile strength.KEYWORDS additive manufacturing, polylactide (PLA), static assessment, fatigue assessment 1 | INTRODUCTION Additive manufacturing (AM) can be described as a collection of technologies that build three-dimensional (3D) objects by systematically adding layer-upon-layer of material. Once a virtual model is produced using a 3D-modelling software, the AM machine reads the data from the file and lays down successive layers of materials to create the 3D solid. This technology facilitates the ease and rapid production of objects with complex geometries that would be more difficult and labour consuming for traditional subtractive manufacturing processes. Industry 4.0 is anticipated to be Nomenclature: k, negative inverse slope; N f , number of cycles to failure; N Ref , reference number of cycles to failure (N Ref = 2·10 6 cycles to failure); P S , probability of survival; R, stress ratio (R = σ min /σ max ); SD, standard deviation; T σ , scatter ratio of the endurance limit, σ max , for 90% and 10% probabilities of survival; θ R , raster angle; σ max , maximum stress in the fatigue cycle; σ MAX,99% , endurance limit at N Ref cycles to failure in terms of σ max ; σ min , minimum stress in the fatigue cycle; σ UTS , ultimate tensile strength

show abstract

“…The impact of fiber content on mechanical behavior of composite was investigated and found that rigidity and effect quality at greatest fiber content were 2.55 and 4.2 occasions to that of unadulterated tar, individually. [7] As per the formulated re-testing talked in this work, when suitable trial outputs can't be created, the weakness evaluation can be performed by utilizing a reference weariness bend with negative backwards incline equivalent to 5.5 and continuance limit. AM PLA is portrayed by a weakness act like the one of PLA produced utilizing customary and entrenched advancements.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Behaviour of PLA and PHBV Based Lignocellulosic Composite Plates

2020

IJRTE

View full text Add to dashboard Cite

The knowledge of 3D printing material used in 3D printing technique is so abundant. Even though there are many critical issues in practical applications. This paper reports the comparison study of the Tensile, Flexural and Impact properties of Environmental friendly composites. This composite material is intended to be used as a replacement for the current 3D printing material. The composite was prepared in compression molding/Injection molding technique under 150 kg/cm2 pressure. This work consists of three specimens. One specimen is Poly Hydroxy Butyrate co Valerate (PHBV) and Sansevieria Roxburghiana. Second specimen is Poly Lactic Acid (PLA) and Sansevieria Roxburghiana and the last specimen is Pure PLA plate. The tensile, impact, flexural strength of pure PLA is comparatively better than the other two composite mixture plates. When comparing the fiber mixture of PLA and PHBV plates the PLA mixture possess greater mechanical properties. The research is further extended by changing the proportion of fiber and also improving the fiber lengths.

show abstract

On the fatigue strength of 3D-printed polylactide (PLA)

Cited by 57 publications

References 13 publications

Static assessment of plain/notched polylactide (PLA) 3D‐printed with different infill levels: Equivalent homogenised material concept and Theory of Critical Distances

Static assessment of plain/notched polylactide (PLA) 3D‐printed with different infill levels: Equivalent homogenised material concept and Theory of Critical Distances

Reference strength values to design against static and fatigue loading polylactide additively manufactured with in‐fill level equal to 100%

Mechanical Behaviour of PLA and PHBV Based Lignocellulosic Composite Plates

Contact Info

Product

Resources

About