scholarly journals Post-Forming Mechanical Properties of a Polymer Sheet Processed by Incremental Sheet Forming: Insights into Effects of Plastic Strain, and Orientation and Size of Specimen

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1870
Author(s):  
Hongyu Wei ◽  
Ghulam Hussain ◽  
Behzad Heidarshenas ◽  
Mohammed Alkahtani
Keyword(s):  
Mechanical Properties ◽  
Plastic Strain ◽  
Tensile Properties ◽  
Yield Stress ◽  
Polymer Structure ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Ultimate Stress ◽  
Polymer Sheet ◽  
Structural Tests

The innovative Incremental Sheet Forming (ISF) process affects the post-forming properties of thermoplastic polymers. However, the effects of degree of plastic strain, and the orientation and size of specimen on the mechanical properties are still unknown. In the present study, therefore, the ISF process is performed on a polymer sheet by varying the plastic strain ranging from 6% to 108%. The corresponding effects on the properties and associated polymer structure are quantified by conducting a variety of mechanical and structural tests. The results reveal that the post-ISF tensile properties like yield stress, ultimate stress, drawing stress, elastic modulus and elongation decrease from 26.6 to 10 MPa, 30.5 to 15.4 MPa, 18.9 to 9.9 MPa, 916 to 300 MPa and 1107% to 457%, respectively, as the strain increases in the investigated range. The value of post-ISF relaxation properties, contrary to the tensile properties, increases with increasing strain up to 62%. Particularly, reductions in stress, strain and modulus increase from 41% to 202%, 37% to 51%, and 41% to 202%. As regard the orientation effect, the sheet in the feed direction shows greater strength than the transverse direction (up to 142% in yield stress and 72% in ultimate stress). Moreover, the smaller sample offers greater strength than the larger one (up to 158% in yield stress and 109% in ultimate stress). The analysis of the post-ISF tensile properties and structural results lead us to conclude that the drop in the tensile properties due to increasing strain occurs due to corresponding increase in the voids area fraction (1.25% to 31%) and a reduction in the crystallinity (38% to 31%).

scholarly journals Mechanical characterization of polylactic acid, polycaprolactone and Lay-Fomm 40 parts manufactured by fused deposition modeling, as a function of the printing parameters

2019 ◽  
Vol 16 (2) ◽  
pp. 25-31 ◽  
Author(s):  
Jessica Zuleima Parrado-Agudelo ◽  
Carlos Narváez-Tovar
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Stress ◽  
Fused Deposition Modeling ◽  
Material Selection ◽  
Ultimate Tensile Stress ◽  
Ultimate Stress ◽  
Fused Deposition ◽  
Raster Angle ◽  
Printing Parameters

This study aims to determine the mechanical properties of parts manufactured by Fused Deposition Modeling (FDM) using three biocompatible polymer materials: Polylactic Acid (PLA), Polycaprolactone (PCL) and Lay-Fomm 40. Also, it was analyzed the influence of different printing parameters, material selection, infill percentage, and raster angle, over the mechanical properties. The samples were subjected to tension and compression tests using a universal testing machine, and elastic modulus, yield stress, and ultimate stress were obtained from the stress-strain curves. PLA samples have the highest elastic modulus, yield stress and ultimate stress for both compression and tension tests, for example, the ultimate tensile stress with infill percentage of 30 % and raster angle of 0-90° has an average value of 41.20 MPa, while PCL samples had an ultimate tensile stress average value of 9.68 MPa. On the other hand, Lay-Fomm40 samples had the highest elongations, with percentage values between 300 and 600 %. Finally, ANOVA analysis showed that the choice of the material is the leading printing parameter that contributes to the mechanical properties, with percentages of 84.20% to elastic modulus, 93.30% to yield stress, and 82.44% to ultimate stress. The second important factor is the raster angle, with higher strengths for the 0-90° when compared to 45-135°. On the other hand, the contribution of the infill percentage to the mechanical properties was no statistically significant. The obtained results could be useful for material selection and 3D printing parameters definition for additive manufacturing of scaffolds, implants, and other structures for biomedical and tissue engineering applications.

Mechanical Properties of an Al-Mg-Sc Alloy Subjected to Intense Plastic Straining

2010 ◽  
Vol 638-642 ◽  
pp. 1952-1958 ◽  
Author(s):  
Rustam Kaibyshev ◽  
Elena Avtokratova ◽  
O.S. Sitdikov
Keyword(s):  
Mechanical Properties ◽  
Cold Rolling ◽  
Yield Stress ◽  
Room Temperature ◽  
Total Elongation ◽  
Warm Rolling ◽  
Ultimate Stress ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
High Reduction

Effect of intense plastic straining on rollability and service properties of an Al-6%Mg-0.3%Sc alloy was examined. Ultrafine-grained structure (UFG) was produced by equal-channel angular pressing (ECAP) to a strain of 8 at a temperature of 325oC. The formation of UFG structure resulted in increase in the yield stress from 223 MPa to 285 MPa and ultimate stress from 350 MPa to 389 MPa in comparison with initial hot extruded condition. Total elongation slightly decreased from 33% to 29%. After ECAP, the material was subjected to cold and isothermal warm rolling. The formation of UFG structure resulted in enhanced rollability of the present alloy at room temperature. Cold rolling with high reduction provides the development of heavily deformed microstructure with high dislocation density, while the isothermal warm rolling does not remarkably affect the microstructure produced by ECAP. The mechanical properties after ECAP and ECAP with subsequent isothermal rolling were roughly similar. In contrast, cold rolling to the same strain resulted in significant increase of yield stress (495 MPa) and ultimate stress (536 MPa). Total elongation attained was 13%.

Tool Directionality in Contour-Based Incremental Sheet Forming: an Experimental Study on Product Properties and Formability

2011 ◽  
Vol 473 ◽  
pp. 897-904 ◽  
Author(s):  
Philip Eyckens ◽  
Hans Vanhove ◽  
Albert Van Bael ◽  
Joost R. Duflou ◽  
Paul van Houtte
Keyword(s):  
Mechanical Properties ◽  
Tool Path ◽  
Thickness Distribution ◽  
Low Carbon Steel ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Movement Direction ◽  
Low Carbon ◽  
Wall Angle ◽  
Product Thickness

The Incremental Sheet Forming (ISF) process offers a large variety in tool path strategies to obtain a particular final product shape. As fundamental understanding of the relevant deformation modes in ISF is growing, the selection of the tool path strategy may be shifted from trial-and-error towards more fundamentally based knowledge of the process characteristics. Truncated cones and pyramids have been fabricated by both unidirectional (UD) and bidirectional (BD) contour-based tool path strategies, considering different wall angles and materials (Mn-Fe alloyed aluminum sheet and low carbon steel sheet). It is shown that the induced through-thickness shear along the tool movement direction is clearly non-zero for UD, in which case the sense of tool movement is the same for all contours, while it is close to 0 for BD, due to the alternating tool sense during consecutive contours. Furthermore, the heterogeneity in product thickness, as observed for the UD strategy in [1,2], is avoided by using the BD strategy. It is verified that this difference in deformation may affect the mechanical properties in the walls of pyramids by means of tensile testing, but the results are material-dependent. For the aluminum alloy, the re-yield stress along the tool movement direction is smaller for BD in comparison to UD, and the fracture strain in large wall angle products is higher. For the steel, no statistically significant differences in mechanical properties between UD- and BD-processed parts are observed. Finally, for both materials a (slightly) higher limiting wall angle has been repeatedly measured using the BD tool strategy. In light of these results, the bidirectional tool path strategy is to be preferred over the unidirectional one, as thickness distribution and formability are more favorable, while both strategies require similar resources and processing time.

scholarly journals Analysis of the Influence of Geometrical Parameters on the Mechanical Properties of Incremental Sheet Forming Parts

2013 ◽  
Vol 63 ◽  
pp. 445-453 ◽  
Author(s):  
J. León ◽  
D. Salcedo ◽  
C. Ciáurriz ◽  
C.J. Luis ◽  
J.P. Fuertes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Geometrical Parameters

Mechanical properties of AZ31 Mg alloy recycled by severe deformation

2006 ◽  
Vol 21 (3) ◽  
pp. 754-760 ◽  
Author(s):  
Yasumasa Chino ◽  
Tetsuji Hoshika ◽  
Jae-Seol Lee ◽  
Mamoru Mabuchi
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Tensile Properties ◽  
Yield Stress ◽  
Tensile Tests ◽  
Extrusion Ratio ◽  
Az31 Mg Alloy ◽  
Reference Specimens ◽  
High Extrusion Ratio

AZ31 Mg machined chips were recycled by extrusion at 673 K with a low extrusion ratio of 45:1 and a high extrusion ratio of 1600:1. Oxide contaminants were dispersed more uniformly in the recycled specimen with the high extrusion ratio than in that with the low extrusion ratio. In tensile tests, the recycled specimens with the high extrusion ratio showed about 50% higher 0.2% yield stress and about 20% higher tensile strength compared with those of the reference specimens, which were the extruded AZ31 Mg blocks under the same conditions as the recycled specimens. The improvement of the tensile properties was attributed not only to the small grain size, but also to the dispersed oxide contaminants.

Numerical Analysis of the Stress/Strain Evolution in Incremental Sheet Forming and Stretch-Bending Processes

2012 ◽  
Vol 713 ◽  
pp. 103-108
Author(s):  
G. Centeno ◽  
C. Vallellano ◽  
J. Vázquez ◽  
F.J. Doblas ◽  
A.J. Martínez-Donaire ◽  
...  
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Hydrostatic Pressure ◽  
Plastic Strain ◽  
Incremental Forming ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Metal Sheet ◽  
Fe Model ◽  
Stretch Bending

In this paper, the evolution of plastic strain and hydrostatic pressure evolutions in incremental sheet forming (ISF) processes to postpone fracture of the metal sheet is analyzed. A finite element (FE) model of an incremental forming operation and a conventional stretch-bending operation is performed. Experimental results of stretching tests are used as reference. The local evolution of the straining and the distribution of hydrostatic pressure are studied in detail. Different step downs and friction coefficients are simulated and their results are discussed.

The effect of vibrations on the mechanical properties of laminations

2021 ◽  
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Yield Stress ◽  
Ultimate Stress ◽  
Vacuum Pressure ◽  
Lamination Process ◽  
Endurance Stress

Abstract This study aims to increase the mechanical properties of the composite material manufactured by the lamination process. In this study, the lamination process will be implemented in two ways, and mechanical properties are compared between the two methods. The first method covers the lamination process under the influence of vacuum pressure only, while in the second method lamination process is achieved by the influence of vacuum pressure and vibrate by shaker device. The results showed that the endurance stress of fatigue increased by 18.18% for the material manufactured by the lamination process under the influence of vibration, while the yield stress and ultimate stress values remained roughly constant for both methods.

scholarly journals Temperature-dependent tensile properties of polyamide 12 for the use in percutaneous transluminal coronary angioplasty balloon catheters

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
C. Amstutz ◽  
B. Weisse ◽  
S. Valet ◽  
A. Haeberlin ◽  
J. Burger ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Coronary Angioplasty ◽  
Young's Modulus ◽  
Percutaneous Transluminal Coronary Angioplasty ◽  
Balloon Catheters ◽  
Transluminal Coronary Angioplasty ◽  
Percutaneous Transluminal

Abstract Background Percutaneous transluminal coronary angioplasty (PTCA) balloon catheters must withstand high pressures required for the lesion treatment, pushing loads during insertion, and pulling loads during withdrawal. These loads pose a challenge especially for polymeric tubular shafts with small cross sections. In order to enable new design innovations and to better understand the mechanics of current catheter technologies, the tensile properties of polyamide (PA) 12 were investigated. PA 12 dog bone specimens and medical PA 12 tubes were either stored at ambient temperature and humidity or conditioned in water, and subjected to tensile loads at different temperatures. In addition, the effect on the tensile properties of the necking process, a forming process to reduce the wall thickness of the tubes, was determined. Results The tested tubes showed a reduction in both Young’s Modulus (− 41.5%) and yield stress (− 29.2%) compared to standardized specimens. Furthermore, an increase in temperature and water absorption softens the material and reduces the mechanical properties like the Young’s Modulus and the yield stress. It was found that the material strengthens during the necking process. Likely due to the orientation of the polymers chain molecules in load direction (Rösler et al., 2007), the Young’s Modulus of the material could be increased by 43.5%. Furthermore, the absence of a yield point after necking allows for a greater loading capacity of the material without unstable neck growth. Besides the strengthening, the ultimate strain is reduced by 50%. This indicates that the necking process induces plastic deformation. Conclusion The investigation showed that the environmental conditions like temperature and humidity can influence mechanical properties. It could also be shown that pre-forming processes such as necking can enhance the mechanical properties, such as the Young’s Modulus, while reducing the wall thickness. These findings suggest possible further development of catheters with a small cross section and higher mechanical strength and highlight the importance to account for the targeted operating temperature during the design process.

scholarly journals Microstructures and High-Temperature Properties of Sm-Modified Mg-4Al-4RE Alloy

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 135
Author(s):  
Hongkui Mao ◽  
Xiaoyu Bai ◽  
Yu Wang ◽  
Hong Xu ◽  
Jibo Hou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Tensile Stress ◽  
Tensile Properties ◽  
Yield Stress ◽  
Room Temperature ◽  
Volume Fraction ◽  
Ultimate Tensile Stress ◽  
New Phase

The effect of Sm on the microstructure and tensile properties of Mg-4Al-4 (La, Ce) alloy was studied. The Mg-4Al-4 (La, Ce) alloy was mainly composed of α-Mg and Al11(La, Ce)3. With the addition of Sm, a new phase of Al2(La, Ce, Sm) was revealed in the alloy. The results showed that at room temperature (RT), after Sm addition, the ultimate tensile stress and the elongation decreased, while the yield stress increased slightly; the elongation increased with the Sm addition and the yield stress was basically the same, but the ultimate tensile stress decreased at an elevated temperature of 150 °C. The change in the mechanical properties of the alloy was mainly related to the change in microstructure and phase. With the increase in Sm content, the volume fraction of Al2(La, Ce, Sm) phase increased and the Al11(La, Ce)3 eutectic volume fraction decreased significantly, which led to a change in the mechanical properties of the alloy. The 1 wt.%Sm-addition alloy exhibited greater elongation than the Sm-free alloys.

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