Predicting Mechanical Properties Based on Slimness Ratio in 3D Printed Samples


Engineers from the US and Brazil delve further into the complexities of mechanical properties in 3D printing, outlining their findings in the recently published ‘ A highly accurate methodology for the prediction and correlation of mechanical properties based on the slimness ratio of additively manufactured tensile test specimens .’
3D printing and additive manufacturing processes continue to make significant impacts in a wide range of industries around the world; however, the more that users begin to rely on such technology and expand regarding innovation and project requirements, greater scrutiny is placed on mechanical properties—whether in regard to shape memory polymers , composite materials , or the effects of details like build orientation . The authors point out that industries like medicine, aerospace, automotive, and more are structured with strict regulations—leaving little room for error in critical applications.
As committees and standards within AM processes are called for, specific efforts are now geared toward:

Classification of new guidelines
Creating file formats for production of parts
Development of criteria for technical reports
General requirements for raw materials

There are still areas lacking required standards, however, such as mechanical characterization of parts. The researchers focus on popular new alloys being used such as Ti–6Al–4, now being used in a variety of AM methods, to include hybrid processes. Tensile testing can be used to assess:

Yield stress (YS)
Ultimate tensile strength (UTS)
Elastic modulus €
Uniform elongation (Elu)
Elongation at fracture (Elf)
Modulus of resilience (Ur)
Tensile toughness (Ut)
Reduction of area (RA)

The authors report that Ti–6Al–4V specimens offered a variety of mechanical property values, as follows.

PBF with laser beam – YS values ranging between 684.3 and 1320.0 MPa, UTS from 480.5 to 1420.0 MPa, and Elf from 1.0 to 24.0%.
DED specimens – tensile properties of YS from 522.0 to 1105.0 MPa, UTS from 716.0 to 1163.0 MPa, and Elf ranging 1.4 to 18.7%.
WAAM process – mechanical properties from YS 800 to 884 MPa, UTS from 887 to 995 MPa, and Elf from 0.5 to 16.5%.
Electron beam melting (EBM) – values of YS, UTS, and Elf ranging from 460 to 1150 MPa, 480 to 1200 MPa, and 1.5 to 25.0%, respectively.

“One of the most important parameters in tensile specimen geometry that directly interferes with the way Elf is measured and which is often neglected by various researchers is the slimness ratio,” stated the researchers.
Other studies have been performed, with a focus on the effects of slimness ratio in tensile specimens; however, the researchers noted both ‘disparity and lack of consensus’ in data in previous literature—leaving them to create a new technique for predicting mechanical...

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