scholarly journals Cracking Patterns of Brittle Hemispherical Domes: an Experimental Study

2021 ◽  
Vol 16 (59) ◽  
pp. 265-310
Author(s):  
Siwen Cao ◽  
Andras A. Sipos
Keyword(s):  
Experimental Study ◽  
Tensile Strength ◽  
Size Distribution ◽  
Crack Formation ◽  
Fragmentation Model ◽  
Track Record ◽  
Hemispherical Dome ◽  
3D Printed ◽  
Loading Tests ◽  
Cracking Pattern

Crack formation in hemispherical domes is a distinguished problem in structural mechanics. The safety of cracked domes has a long track record; the evolution of the cracking pattern received less attention. Here, we report displacement-controlled loading tests of brittle hemispherical dome specimens, including the evolution of the meridional cracking pattern. The 27 investigated specimens, 20 cm in diameter, were prepared in 3D printed molds, and their material is one of the three mixtures of gypsum and cement. We find that neither the (limited) tensile strength nor the exact value of the thickness significantly affects the statistical description of the cracking pattern, i.e., the cracking phenomenon is robust. The maximal number of the meridional cracks never exceeds seven before the fragments’ disintegration (collapse). We find that the size distribution of the fragments exhibits a lognormal distribution. The evolution is reflected in the load-displacement diagrams recorded in the test, too, as significant drops in the force are accompanied by an emergence of one or more new cracks, reflecting the brittle nature of the phenomenon. A simple, stochastic fragmentation model, in which a segment is fragmented at either in the middle or at the fourth point, fairly recovers the observed size distribution.

scholarly journals Performance Assessment of 3d Printed Parts Fabricated By Fdm using Three Different Materails

2019 ◽  
Vol 9 (1) ◽  
pp. 959-962
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Performance Assessment ◽  
Three Dimensional ◽  
Three Dimensional Printing ◽  
Taguchi Design Of Experiment ◽  
3D Printed ◽  
Dimensional Printing

A tremendous research has been notices in the field of three dimensional printing. An experimental study has been carried out for three dimensional printing to analyses the surface roughness and ultimate tensile strength of three different materials. The study has been conducted using Taguchi design of experiment. from the study it has been depicted that the infill percentage has a significant effect on the output.

Tensile strength of 3D printed materials: Review and reassessment of test parameters

2018 ◽  
Vol 60 (7-8) ◽  
pp. 679-686 ◽  
Author(s):  
Jim Floor ◽  
Bas van Deursen ◽  
Erik Tempelman
Keyword(s):  
Tensile Strength ◽  
Test Parameters ◽  
3D Printed ◽  
Printed Materials

scholarly journals The Direct 3D Printing of Functional PEEK/Hydroxyapatite Composites via a Fused Filament Fabrication Approach

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 545
Author(s):  
Krzysztof Rodzeń ◽  
Preetam K. Sharma ◽  
Alistair McIlhagger ◽  
Mozaffar Mokhtari ◽  
Foram Dave ◽  
...  
Keyword(s):  
Tensile Strength ◽  
3D Printing ◽  
Selective Laser Sintering ◽  
Fused Filament Fabrication ◽  
Bone Apposition ◽  
Innovative Solutions ◽  
3D Printed ◽  
Work Samples ◽  
Viable Approach ◽  
Crystalline Domains

The manufacture of polyetheretherketone/hydroxyapatite (PEEK/HA) composites is seen as a viable approach to help enhance direct bone apposition in orthopaedic implants. A range of methods have been used to produce composites, including Selective Laser Sintering and injection moulding. Such techniques have drawbacks and lack flexibility to manufacture complex, custom-designed implants. 3D printing gets around many of the restraints and provides new opportunities for innovative solutions that are structurally suited to meet the needs of the patient. This work reports the direct 3D printing of extruded PEEK/HA composite filaments via a Fused Filament Fabrication (FFF) approach. In this work samples are 3D printed by a custom modified commercial printer Ultimaker 2+ (UM2+). SEM-EDX and µCT analyses show that HA particles are evenly distributed throughout the bulk and across the surface of the native 3D printed samples, with XRD highlighting up to 50% crystallinity and crystalline domains clearly observed in SEM and HR-TEM analyses. This highlights the favourable temperature conditions during 3D printing. The yield stress and ultimate tensile strength obtained for all the samples are comparable to human femoral cortical bone. The results show how FFF 3D printing of PEEK/HA composites up to 30 wt% HA can be achieved.

scholarly journals The Influence of the Asymmetric Arb Process on the Properties of Al-Mg-Al Multi-Layer Sheets / Wpływ Asymetrii W Procesie Arb Na Właściwości Wielowarstwowych Blach Al-Mg-Al

2015 ◽  
Vol 60 (4) ◽  
pp. 2821-2826 ◽  
Author(s):  
A. Wierzba ◽  
S. Mróz ◽  
P. Szota ◽  
A. Stefanik ◽  
R. Mola
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Tensile Strength ◽  
Rolling Process ◽  
Asymmetry Factor ◽  
Relative Reduction ◽  
Test Results ◽  
Initial Thickness ◽  
Asymmetric Rolling ◽  
Aluminium Layer

The paper presents the results of the experimental study of the three-layer Al-Mg-Al sheets rolling process by the ARB method. The tests carried out were limited to single-pass symmetric and asymmetric rolling processes. An Al-Mg-Al package with an initial thickness of 4 mm (1-2-1 mm) was subjected to the process of rolling with a relative reduction of 50%. To activate the shear band in the strip being deformed, an asymmetry factor of av=2 was applied. From the test results, an increase in the tensile strength of the multi-layer Al-Mg-Al sheets obtained from the asymmetric process was observed. Microhardness tests did not show any significant differences in aluminium layer between respective layers of sheets obtained from the symmetric and the asymmetric process. By contrast, for the magnesium layer, an increase in microhardness from 72 HV to 79 HV could be observed for the asymmetric rolling. The analysis of the produced Al-Mg-Al sheets shows that the good bond between individual layers and grain refinement in the magnesium layer contributed to the obtaining of higher mechanical properties in the multi-layer sheets produced in the asymmetric process compared to the sheets obtained from the symmetric process.

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