scholarly journals Geometrical Scaling Effects in the Mechanical Properties of 3D-Printed Body-Centered Cubic (BCC) Lattice Structures

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3967
Author(s):  
Alia Ruzanna Aziz ◽  
Jin Zhou ◽  
David Thorne ◽  
Wesley James Cantwell
Keyword(s):  
Mechanical Properties ◽  
Compression Strength ◽  
Size Effects ◽  
Failure Modes ◽  
Mechanical Response ◽  
The Body ◽  
Lattice Structures ◽  
Body Centered Cubic ◽  
Scaling Effects ◽  
Modes Of Failure

This paper investigates size effects on the mechanical response of additively manufactured lattice structures based on a commercially available polylactic acid (PLA) polymer. Initial attention is focused on investigating geometrical effects in the mechanical properties of simple beams and cubes. Following this, a number of geometrically scaled lattice structures based on the body-centered cubic design were manufactured and tested in order to highlight size effects in their compression properties and failure modes. A finite element analysis was also conducted in order to compare the predicted modes of failure with those observed experimentally. Scaling effects were observed in the compression response of the PLA cubes, with the compression strength increasing by approximately 19% over the range of scale sizes investigated. Similar size-related effects were observed in the flexural samples, where a brittle mode of failure was observed at all scale sizes. Here, the flexural strength increased by approximately 18% when passing from the quarter size sample to its full-scale counterpart. Significant size effects were observed following the compression tests on the scaled lattice structures. Here, the compression strength increased by approximately 60% over the four sample sizes, in spite of the fact that similar failure modes were observed in all samples. Finally, reasonably good agreement was observed between the predicted failure modes and those observed experimentally. However, the FE models tended to over-estimate the mechanical properties of the lattice structures, probably as a result of the fact that the models were assumed to be defect free.

scholarly journals An investigation of the mechanical properties of metallic lattice structures fabricated using selective laser melting

2016 ◽  
Vol 232 (10) ◽  
pp. 1719-1730 ◽  
Author(s):  
Qixiang Feng ◽  
Qian Tang ◽  
Zongmin Liu ◽  
Ying Liu ◽  
Rossi Setchi
Keyword(s):  
Mechanical Properties ◽  
Selective Laser Melting ◽  
Lightweight Design ◽  
Weight Ratio ◽  
Essential Element ◽  
Theoretical Method ◽  
The Body ◽  
Lattice Structures ◽  
Body Centered Cubic ◽  
Laser Melting

Metallic lattice structures manufactured using selective laser melting are widely used in fields such as aerospace and automobile industries in order to save material and reduce energy consumption. An essential element of metallic lattice structures design is determining their mechanical behaviors under loading conditions. Theoretical method based on beam theory has been proposed for evaluating the behaviors of the commonly used body-centered cubic lattice structures. However, it is difficult to predict theoretically the properties of the uniaxially reinforced lattice structures based on the body-centered cubic structures. Since the reinforced structures have superior strength to weight ratio and are deemed promising in lightweight-design applications, this article proposed a force-method-based theoretical method to calculate the mechanical properties of the body-centered cubic structure and its two types of uniaxially reinforced structures fabricated via selective laser melting. The finite element analysis and compression experiment study of selective laser melting samples made using Ti6Al4V powders demonstrated the validity of the proposed analytical method.

Failure Behaviour of Semantan Bamboo Strips Loaded in Bending and Shear

2011 ◽  
Vol 462-463 ◽  
pp. 1176-1181
Author(s):  
Shahril Anuar Bahari ◽  
Mansur Ahmad
Keyword(s):  
Mechanical Properties ◽  
Microscopic Observation ◽  
Maximum Stress ◽  
Failure Modes ◽  
Vascular Bundles ◽  
Failure Behaviour ◽  
Modes Of Failure ◽  
Different Parts

In this study, the classification of modes of failure, the observation of microscopic failures and the mechanical properties of Semantan bamboo strips were investigated. Specimens were loaded in bending and shear parallel to grain. Specimens were taken from internodes and node parts in bottom, middle and top portions of bamboo culms. From the classification, different modes of failure occurred in different parts of Semantan bamboo culms loaded in bending and shear. From the microscopic observation, the failures occurred in both parenchyma and vascular bundles regions for all classified failure modes from all tests, except for Even Splitting Mode from shear. This mode exhibited failure in parenchyma only, without any failure in vascular bundles regions. The Maximum Stress (σml) values between failure modes for both tests were significantly different. Generally, anatomical behaviour at different culm’s parts had influenced the different modes of failure and microscopic failures of Semantan bamboo strips loaded in bending and shear.

scholarly journals Physical–Mechanical Characteristics and Microstructure of Ti6Al7Nb Lattice Structures Manufactured by Selective Laser Melting

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4123
Author(s):  
Cosmin Cosma ◽  
Igor Drstvensek ◽  
Petru Berce ◽  
Simon Prunean ◽  
Stanisław Legutko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Selective Laser Melting ◽  
Failure Modes ◽  
Young Modulus ◽  
Phase Identification ◽  
Lattice Structures ◽  
Laser Melting ◽  
Fracture Characterization ◽  
Static Compression ◽  
Brittle Rupture

The demand of lattice structures for medical applications is increasing due to their ability to accelerate the osseointegration process, to reduce the implant weight and the stiffness. Selective laser melting (SLM) process offers the possibility to manufacture directly complex lattice applications, but there are a few studies that have focused on biocompatible Ti6Al7Nb alloy. The purpose of this work was to investigate the physical–mechanical properties and the microstructure of three dissimilar lattice structures that were SLM-manufactured by using Ti6Al7Nb powder. In particular, the strut morphology, the fracture characterization, the metallographic structure, and the X-ray phase identification were analyzed. Additionally, the Gibson-Ashby prediction model was adapted for each lattice topology, indicating the theoretical compressive strength and Young modulus. The resulted porosity of these lattice structures was approximately 56%, and the pore size ranged from 0.40 to 0.91 mm. Under quasi-static compression test, three failure modes were recorded. Compared to fully solid specimens, the actual lattice structures reduce the elastic modulus from 104 to 6–28 GPa. The struts surfaces were covered by a large amount of partial melted grains. Some solidification defects were recorded in struts structure. The fractographs revealed a brittle rupture of struts, and their microstructure was mainly α’ martensite with columnar grains. The results demonstrate the suitability of manufacturing lattice structures made of Ti6Al7Nb powder having unique physical–mechanical properties which could meet the medical requirements.

scholarly journals Spinodal Decomposition and Mechanical Response of a TiZrNbTa High-Entropy Alloy

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3508 ◽  
Author(s):  
Liu ◽  
Huang ◽  
Chuang ◽  
Chou ◽  
Wei ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Spinodal Decomposition ◽  
Mechanical Response ◽  
Cast Alloy ◽  
High Entropy Alloy ◽  
Body Centered Cubic ◽  
High Entropy ◽  
Bcc Structure ◽  
20 Nm ◽  
Interconnected Structure

In this study, the effects of spinodal decomposition on the microstructures and mechanical properties of a TiZrNbTa alloy are investigated. The as-cast TiZrNbTa alloy possesses dual phases of TiZr-rich inter-dendrite (ID) and NbTa-rich dendrite (DR) domains, both of which have a body-centered cubic (BCC) structure. In the DRs of the as-cast alloy, the α and ω precipitates are found to be uniformly distributed. After homogenization at 1100 °C for 24 h followed by water quenching, spinodal decomposition occurs and an interconnected structure with a wavelength of 20 nm is formed. The α and ω precipitates remained in the structure. Such a fine spinodal structure strengthens the alloy effectively. Detailed strengthening calculations were conducted in order to estimate the strengthening contributions from the α and ω precipitates, as well as the spinodal decomposition microstructure.

Measurement of the axial and circumferential mechanical properties of rat skin tissue at different anatomical locations

2015 ◽  
Vol 60 (2) ◽  
Author(s):  
Alireza Karimi ◽  
Maedeh Haghighatnama ◽  
Mahdi Navidbakhsh ◽  
Afsaneh Motevalli Haghi
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Clinical Decision Making ◽  
Mechanical Response ◽  
The Body ◽  
Skin Tissue ◽  
Linear Elastic ◽  
Biomechanical Models ◽  
Nonlinear Mechanical

AbstractSkin tissue is not only responsible for thermoregulation but also for protecting the human body from mechanical, bacterial, and viral insults. The mechanical properties of skin tissue may vary according to the anatomical locations in the body. However, the linear elastic and nonlinear hyperelastic mechanical properties of the skin in different anatomical regions and at different loading directions (axial and circumferential) so far have not been determined. In this study, the mechanical properties during tension of the rat abdomen and back were calculated at different loading directions using linear elastic and nonlinear hyperelastic material models. The skin samples were subjected to a series of tensile tests. The elastic modulus and maximum stress of the skin tissues were measured before the incidence of failure. The nonlinear mechanical behavior of the skin tissues was also computationally investigated through a constitutive equation. Hyperelastic strain energy density function was calibrated using the experimental data. The results revealed the anisotropic mechanical behavior of the abdomen and the isotropic mechanical response of the back skin. The highest elastic modulus was observed in the abdomen skin under the axial direction (10 MPa), while the lowest one was seen in the back skin under axial loading (5 MPa). The Mooney-Rivlin material model closely addressed the nonlinear mechanical behavior of the skin at different loading directions, which can be implemented in the future biomechanical models of skin tissue. The results might have implications not only for understanding of the isotropic and anisotropic mechanical behavior of skin tissue at different anatomical locations but also for providing more information for a diversity of disciplines, including dermatology, cosmetics industry, clinical decision making, and clinical intervention.

scholarly journals Improved Mechanical Properties and Energy Absorption of BCC Lattice Structures with Triply Periodic Minimal Surfaces Fabricated by SLM

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2411 ◽  
Author(s):  
Miao Zhao ◽  
Fei Liu ◽  
Guang Fu ◽  
David Zhang ◽  
Tao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Computer Aided Design ◽  
Volume Fraction ◽  
Lattice Structure ◽  
The Body ◽  
Lattice Structures ◽  
Volume Fractions ◽  
Lattice Design ◽  
Bcc Lattice ◽  
Triply Periodic

The triply periodic minimal surface (TPMS) method is a novel approach for lattice design in a range of fields, such as impact protection and structural lightweighting. In this paper, we used the TPMS formula to rapidly and accurately generate the most common lattice structure, named the body centered cubic (BCC) structure, with certain volume fractions. TPMS-based and computer aided design (CAD) based BCC lattice structures with volume fractions in the range of 10–30% were fabricated by selective laser melting (SLM) technology with Ti–6Al–4V and subjected to compressive tests. The results demonstrated that local geometric features changed the volume and stress distributions, revealing that the TPMS-based samples were superior to the CAD-based ones, with elastic modulus, yield strength and compression strength increasing in the ranges of 18.9–42.2%, 19.2–29.5%, and 2–36.6%, respectively. The failure mechanism of the TPMS-based samples with a high volume fraction changed to brittle failure observed by scanning electron microscope (SEM), as their struts were more affected by the axial force and fractured on struts. It was also found that the TPMS-based samples have a favorable capacity to absorb energy, particularly with a 30% volume fraction, the energy absorbed up to 50% strain was approximately three times higher than that of the CAD-based sample with an equal volume fraction. Furthermore, the theoretic Gibson–Ashby mode was established in order to predict and design the mechanical properties of the lattice structures. In summary, these results can be used to rapidly create BCC lattice structures with superior compressive properties for engineering applications.

Effect of strut length and orientation on elastic mechanical response of modified body-centered cubic lattice structures

2019 ◽  
Vol 233 (11) ◽  
pp. 2219-2233 ◽  
Author(s):  
Hasanain S Abdulhadi ◽  
Ahsan Mian
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
Reference Model ◽  
Computational Time ◽  
Lattice Structures ◽  
Body Centered Cubic ◽  
Angle Variation ◽  
Fused Deposition ◽  
Finite Element Software ◽  
Wide Range

Lattice structures (LSs) have been exploited for wide range of applications including mechanical, thermal, and biomedical structures because of their unique attributes combining the light weight and high strength. The main goal of this research is to investigate the effect of strut length and orientation on the mechanical characteristics of modified body-centered cubic (BCC) LS subjected to a quasi-static axial compressive loading within linear elastic limit using finite element analysis. In this study, two sets of LS were built and analyzed in commercial finite element software, ABAQUS/CAE/EXPLICIT 6.16, using a “smart procedure,” which was developed for this research to reduce the computational time and increase the accuracy of results by creating hexahedral mesh elements. The first set comprises 13 models having fixed strut length with strut angle variation from 40° to 100° with a step of 5°. The second set also includes 13 models; however, having variant strut length, kept constant for a single unit cell and through the entire model but varied from one model to another, with the same strut angle variation as the first set. In addition, the BCC LS with a strut angle of 70.53° was replicated in both sets because it was considered as a reference model to compare the results with it. Furthermore, specimens of the reference model were fabricated by a fused deposition modeling- (FDM) based 3D printer using acrylonitrile butadiene styrene (ABS) material and tested experimentally under compression. Experimental results are observed to be in good agreement with those of the finite element simulation, hence the same loading and boundary conditions were adopted for all other models. It was observed that the fixed strut length BCC LS with a strut angle of 100° offers the highest modulus. However, the highest specific strain energy absorption and specific stiffness as well as the least value of weight were dictated by a variant strut length BCC LS with a strut angle of 40°.

scholarly journals FDM Layering Deposition Effects on Mechanical Response of TPU Lattice Structures

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5645
Author(s):  
Chiara Ursini ◽  
Luca Collini
Keyword(s):  
Mechanical Properties ◽  
Fused Deposition Modeling ◽  
Mechanical Response ◽  
Lattice Structures ◽  
Fused Deposition ◽  
Functional Behavior ◽  
Unit Cells ◽  
Best Parameter ◽  
Materials Used ◽  
Parts Manufacturing

Nowadays, fused deposition modeling additive technology is becoming more and more popular in parts manufacturing due to its ability to reproduce complex geometries with many different thermoplastic materials, such as the TPU. On the other hand, objects obtained through this technology are mainly used for prototyping activities. For this reason, analyzing the functional behavior of FDM parts is still a topic of great interest. Many studies are conducted to broaden the spectrum of materials used to ensure an ever-increasing use of FDM in various production scenarios. In this study, the effects of several phenomena that influence the mechanical properties of printed lattice structures additively obtained by FDM are evaluated. Three different configurations of lattice structures with designs developed from unit cells were analyzed both experimentally and numerically. As the main result of the study, several parameters of the FDM process and their correlation were identified as possible detrimental factors of the mechanical properties by about 50% of the same parts used as isotropic cell solids. The best parameter configurations in terms of mechanical response were then highlighted by numerical analysis.

Mechanical Properties and Adhesion of PZT Thin Films for MEMS

1999 ◽  
Vol 594 ◽  
Author(s):  
J. M. Jungk ◽  
B. T. Crozier ◽  
A. Bandyopadhyay ◽  
N. R. Moody ◽  
D. F. Bahr
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Failure Modes ◽  
Microelectromechanical Systems ◽  
Mechanical Response ◽  
Lead Zirconate ◽  
Silicon Substrates ◽  
Sensors And Actuators ◽  
Solution Deposition ◽  
Ability To Act

AbstractPiezoelectric films are attractive materials for use in microelectromechanical systems (MEMS) due to their ability to act as both sensors and actuators. One of the primary modes of deformation is the deflection of lead zirconate titantate (PZT) beams and membranes, where the adhesion of the film is critical for the reliability of the device. Thin films of PZT between 250 and 750 nm have been grown via solution deposition routes onto platinized silicon substrates. The films have been tested using nanoindentation techniques. Two failure mechanism in these films have been observed Indentation induced delamination at the PZT-Pt interface occurs after the indenter tip is removed from the film when loads between 1 and 10 mN are applied to the sample, and at large loads (>75 mN) failure can be generated between the underlying oxide film and the silicon substrate while the tip is still engaged with the sample. Since each of these failure modes has a different mechanics solution, the results are compared to determine adhesion energy of the films. Fracture around the delaminated regions has been examined using scanning probe and electron microscopy. Freestanding PZT membranes above micromachined cavities have been mechanically deformed to examine the mechanical response and failure modes in these structures. The adhesion of the PZT improves with increased percent crystallization due to the introduction of residual tensile stresses. Processing, mechanical properties, and failure modes in these devices will be discussed.

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