Publications by authors named "Nima Shamsaei"

13 Publications

  • Page 1 of 1

Phase-Selective and Localized TiO Coating on Additive and Wrought Titanium by a Direct Laser Surface Modification Approach.

ACS Omega 2020 Jul 2;5(27):16744-16751. Epub 2020 Jul 2.

Department of Electrical and Computer Engineering, Auburn University, Auburn, Alabama 36849, United States.

Titanium has been the material of interest in biological implant applications due to its unique mechanical properties and biocompatibility. Their design is now growing rapidly due to the advent of additive manufacturing technology that enables the fabrication of complex and patient-customized parts. Titanium dioxides (TiO) coatings with different phases (e.g., anatase, rutile) and morphologies have shown to be effective in enhancing osteointegration and antibacterial behavior. This enhanced antibacterial behavior stems from the photocatalytic activity generated from crystalline TiO coatings. Anatase has commonly been shown to be a more photocatalytic oxide phase compared to rutile despite its larger band gap. However, more recent studies have suggested that a synergistic effect leading to increased photocatalytic activity may be produced with a combination of oxides containing both anatase and rutile phases. Here, we demonstrate the selective and localized formation of TiO nanostructures on additive and wrought titanium parts with anatase, rutile, and mixed phases by a laser-induced transformation approach. Compared to conventional coating processes, this technique produces desired TiO phases simply by controlled laser irradiation of titanium parts in an oxygen environment, where needed. The effects of processing conditions such as laser power, scanning speed, laser pulse duration, frequency, and gas flow on the selective transformation were studied. The morphological and structural evolutions were investigated using various characterization techniques. This method is specifically of significant interest in creating phase-selective TiO surfaces on titanium-based bioimplants, including those fabricated by additive manufacturing technologies.
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http://dx.doi.org/10.1021/acsomega.0c01671DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7364727PMC
July 2020

Dexamethasone eluting 3D printed metal devices for bone injuries.

Ther Deliv 2020 06 1;11(6):373-386. Epub 2020 Jun 1.

Department of Drug Discovery & Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA.

Additively manufactured (3D printed), stainless steel implants were coated with dexamethasone using gelatin, chondroitin sulfate for use in bone graft surgeries. The drug and polymers were deposited on the implants with a rough surface using a high precision air brush. The gelatin-chondroitin sulfate layers were cross-linked using glutaraldehyde. The drug content uniformity was within 100 ± 5%, and the thickness of the polymer layer was 410 ± 5.2 μm. The release studies showed a biphasic pattern with an initial burst release followed by slow release up to 3 days. These results are very promising as the slow release implants can be further tested in large animals, such as cattle and horses to prevent the inflammatory cascade following surgeries.
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http://dx.doi.org/10.4155/tde-2020-0014DOI Listing
June 2020

Fatigue data for laser beam powder bed fused 17-4 PH stainless steel specimens in different heat treatment and surface roughness conditions.

Data Brief 2019 Aug 4;25:104215. Epub 2019 Jul 4.

Department of Mechanical Engineering, Auburn University, Auburn, AL 36849, USA.

This article presents the data demonstrating the synergistic effect of surface roughness and heat treatment on the fatigue behavior of 17-4 PH stainless steel (SS) fabricated via laser beam powder bed fusion (LB-PBF) [1]. Two sets of specimens, in as-built and machined surface conditions, were heat treated using five different recommended procedures for 17-4 PH SS by ASTM A693. Axial fully-reversed fatigue tests (R = -1) were conducted on heat treated as-built and machined specimens. The stable hysteresis stress-strain data, as well as the maximum and minimum stress and strain values for the cycle in a log10 increment are included for all conducted fatigue experiments. In addition, fractography images are provided for selected set of specimens.
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http://dx.doi.org/10.1016/j.dib.2019.104215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6646923PMC
August 2019

Residual stress measurements via neutron diffraction of additive manufactured stainless steel 17-4 PH.

Data Brief 2017 Aug 16;13:408-414. Epub 2017 Jun 16.

Laboratory for Fatigue & Additive Manufacturing Excellence (FAME), Department of Mechanical Engineering, Auburn University, Auburn, AL 36849, United States.

Neutron diffraction was employed to measure internal residual stresses at various locations along stainless steel (SS) 17-4 PH specimens additively manufactured via laser-powder bed fusion (L-PBF). Of these specimens, two were rods (diameter=8 mm, length=80 mm) built vertically upward and one a parallelepiped (8×80×9 mm) built with its longest edge parallel to ground. One rod and the parallelepiped were left in their as-built condition, while the other rod was heat treated. Data presented provide insight into the microstructural characteristics of typical L-PBF SS 17-4 PH specimens and their dependence on build orientation and post-processing procedures such as heat treatment. Data have been deposited in the Data in Brief Dataverse repository (doi:10.7910/DVN/T41S3V).
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http://dx.doi.org/10.1016/j.dib.2017.06.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5480826PMC
August 2017

Cyclic deformation and fatigue data for Ti-6Al-4V ELI under variable amplitude loading.

Data Brief 2017 Aug 19;13:180-186. Epub 2017 May 19.

US Army Engineer Research and Development Center, Vicksburg, MS 39180, USA.

This article presents the strain-based experimental data for Ti-6Al-4V ELI under non-constant amplitude cyclic loading. Uniaxial strain-controlled fatigue experiments were conducted under three different loading conditions, including two-level block loading (i.e. high-low and low-high), periodic overload, and variable amplitude loading. Tests were performed under fully-reversed, and mean strain/stress conditions. For each test conducted, two sets of data were collected; the cyclic stress-strain response (i.e. hysteresis loops) in log increments, and the peak and valley values of stress and strain for each cycle. Residual fatigue lives are reported for tests with two-level block loading, while for periodic overload and variable amplitude experiments, fatigue lives are reported in terms of number of blocks to failure.
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http://dx.doi.org/10.1016/j.dib.2017.05.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5458061PMC
August 2017

Data indicating temperature response of Ti-6Al-4V thin-walled structure during its additive manufacture via Laser Engineered Net Shaping.

Data Brief 2016 Jun 9;7:697-703. Epub 2016 Mar 9.

Department of Mechanical Engineering, Mississippi State University, PO Box 9552, 39762 MS, USA; Center for Advanced Vehicular Systems (CAVS), Mississippi State University, PO Box 5405, 39762 MS, USA.

An OPTOMEC Laser Engineered Net Shaping (LENS(™)) 750 system was retrofitted with a melt pool pyrometer and in-chamber infrared (IR) camera for nondestructive thermal inspection of the blown-powder, direct laser deposition (DLD) process. Data indicative of temperature and heat transfer within the melt pool and heat affected zone atop a thin-walled structure of Ti-6Al-4V during its additive manufacture are provided. Melt pool temperature data were collected via the dual-wavelength pyrometer while the dynamic, bulk part temperature distribution was collected using the IR camera. Such data are provided in Comma Separated Values (CSV) file format, containing a 752×480 matrix and a 320×240 matrix of temperatures corresponding to individual pixels of the pyrometer and IR camera, respectively. The IR camera and pyrometer temperature data are provided in blackbody-calibrated, raw forms. Provided thermal data can aid in generating and refining process-property-performance relationships between laser manufacturing and its fabricated materials.
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http://dx.doi.org/10.1016/j.dib.2016.02.084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4802429PMC
June 2016

Data demonstrating the effects of build orientation and heat treatment on fatigue behavior of selective laser melted 17-4 PH stainless steel.

Data Brief 2016 Jun 10;7:89-92. Epub 2016 Feb 10.

Department of Mechanical Engineering, Mississippi State University, Box 9552, Mississippi State, MS 39762, USA; Center for Advanced Vehicular Systems (CAVS), Mississippi State University, Box 5405, Mississippi State, MS 39762, USA.

Axial fully-reversed strain-controlled ([Formula: see text]) fatigue experiments were performed to obtain data demonstrating the effects of building orientation (i.e. vertical versus horizontal) and heat treatment on the fatigue behavior of 17-4 PH stainless steel (SS) fabricated via Selective Laser Melting (SLM) (Yadollahi et al., submitted for publication [1]). This data article provides detailed experimental data including cyclic stress-strain responses, variations of peak stresses during cyclic deformation, and fractography of post-mortem specimens for SLM 17-4 PH SS.
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http://dx.doi.org/10.1016/j.dib.2016.02.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4761700PMC
June 2016

Strain-based fatigue data for Ti-6Al-4V ELI under fully-reversed and mean strain loads.

Data Brief 2016 Jun 9;7:12-5. Epub 2016 Feb 9.

Department of Mechanical Engineering, Mississippi State University, Box 9552, Mississippi State, MS 39762, USA; Center for Advanced Vehicular Systems (CAVS), Mississippi State University, Box 5405, Mississippi State, MS 39762, USA.

This article presents the experimental data supporting the study to obtain the mean strain/stress effects on the fatigue behavior of Ti-6Al-4V ELI. A series of strain-controlled fatigue experiments on Ti-6Al-4V ELI were performed at four strain ratios (-1, -0.5, 0, and 0.5). Two types of data are included for each specimen. These are the hysteresis stress-strain responses for the cycle in a log10 increment, and the maximum and minimum stress-strain responses for each cycle. Fatigue lives are also reported for all the experiments.
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http://dx.doi.org/10.1016/j.dib.2016.02.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4761652PMC
June 2016

Data related to cyclic deformation and fatigue behavior of direct laser deposited Ti-6Al-4V with and without heat treatment.

Data Brief 2016 Mar 4;6:970-3. Epub 2016 Feb 4.

Department of Mechanical Engineering, Mississippi State University, Box 9552, MS 39762, United States; Center for Advanced Vehicular Systems (CAVS), Mississippi State University, Box 5405, MS 39762, United States.

Data is presented describing the strain-controlled, fully-reversed uniaxial cyclic deformation and fatigue behavior of Ti-6Al-4V specimens additively manufactured via Laser Engineered Net Shaping (LENS) - a Direct Laser Deposition (DLD) process. The data was collected by performing multiple fatigue tests on specimens with various microstructural states/conditions, i.e. in their 'as-built', annealed (below the beta transus temperature), or heat treated (above the beta transus temperature) condition. Such data aids in characterizing the mechanical integrity and fatigue resistance of DLD parts. Data presented herein also allows for elucidating the strong microstructure coupling of the fatigue behavior of DLD Ti-6Al-4V, as the data trends were found to vary with material condition (i.e. as-built, annealed or heat treated) [1]. This data is of interest to the additive manufacturing and fatigue scientific communities, as well as the aerospace and biomedical industries, since additively-manufactured parts cannot be reliably deployed for public use, until their mechanical properties are understood with high certainty.
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http://dx.doi.org/10.1016/j.dib.2016.01.059DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4758181PMC
March 2016

Fatigue data for polyether ether ketone (PEEK) under fully-reversed cyclic loading.

Data Brief 2016 Mar 3;6:881-4. Epub 2016 Feb 3.

Department of Mechanical Engineering, Mississippi State University, Box 9552, Mississippi State, MS 39762, USA; Center for Advanced Vehicular Systems (CAVS), Mississippi State University, Box 5405, Mississippi State, MS 39762, USA.

In this article, the data obtained from the uniaxial fully-reversed fatigue experiments conducted on polyether ether ketone (PEEK), a semi-crystalline thermoplastic, are presented. The tests were performed in either strain-controlled or load-controlled mode under various levels of loading. The data are categorized into four subsets according to the type of tests, including (1) strain-controlled fatigue tests with adjusted frequency to obtain the nominal temperature rise of the specimen surface, (2) strain-controlled fatigue tests with various frequencies, (3) load-controlled fatigue tests without step loadings, and (4) load-controlled fatigue tests with step loadings. Accompanied data for each test include the fatigue life, the maximum (peak) and minimum (valley) stress-strain responses for each cycle, and the hysteresis stress-strain responses for each collected cycle in a logarithmic increment. A brief description of the experimental method is also given.
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http://dx.doi.org/10.1016/j.dib.2016.01.052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4752734PMC
March 2016

Multiaxial fatigue modeling for Nitinol shape memory alloys under in-phase loading.

J Mech Behav Biomed Mater 2015 Mar 2;55:236-249. Epub 2015 Nov 2.

Department of Mechanical Engineering, Mississippi State University, Box 9552, Mississippi State, MS 39762, United States; Center for Advanced Vehicular Systems (CAVS), Mississippi State University, Box 5405, Mississippi State, MS 39762, United States. Electronic address:

The realistic loading condition for many components is multiaxial arising from multidirectional loading or geometry complexities. In this study, some multiaxial stress-based classical and critical plane fatigue models are briefly reviewed and their application for martensitic Nitinol under torsion and in-phase axial-torsion loading is evaluated. These models include von Mises equivalent stress, Tresca, Findley, McDiarmid, and a proposed stress-based Fatemi-Socie-type model. As the fatigue cracks appear to be on the maximum shear plane for the martensitic Nitinol, all the models examined here consider the shear stress as the primary damage parameter. Among all the models considered in this study, the proposed Fatemi-Socie-type model provides a better prediction for fatigue lives when compared to torsion and in-phase multiaxial fatigue experimental data from literature. Analyses indicate that critical plane approaches are more appropriate for multiaxial fatigue prediction of Nitinol alloys, at least in martensitic phase. Finally, recommendations are made to calibrate more reliable multiaxial fatigue models for Nitinol.
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http://dx.doi.org/10.1016/j.jmbbm.2015.10.022DOI Listing
March 2015

Effects of microstructural inclusions on fatigue life of polyether ether ketone (PEEK).

J Mech Behav Biomed Mater 2015 Nov 30;51:388-97. Epub 2015 Jul 30.

U.S. Army Engineer Research and Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180, USA.

In this study, the effects of microstructural inclusions on fatigue life of polyether ether ketone (PEEK) was investigated. Due to the versatility of its material properties, the semi-crystralline PEEK polymer has been increasingly adopted in a wide range of applications particularly as a biomaterial for orthopedic, trauma, and spinal implants. To obtain the cyclic behavior of PEEK, uniaxial fully-reversed strain-controlled fatigue tests were conducted at ambient temperature and at 0.02 mm/mm to 0.04 mm/mm strain amplitudes. The microstructure of PEEK was obtained using the optical and the scanning electron microscope (SEM) to determine the microstructural inclusion properties in PEEK specimen such as inclusion size, type, and nearest neighbor distance. SEM analysis was also conducted on the fracture surface of fatigue specimens to observe microstructural inclusions that served as the crack incubation sites. Based on the experimental strain-life results and the observed microstructure of fatigue specimens, a microstructure-sensitive fatigue model was used to predict the fatigue life of PEEK that includes both crack incubation and small crack growth regimes. Results show that the employed model is applicable to capture microstructural effects on fatigue behavior of PEEK.
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http://dx.doi.org/10.1016/j.jmbbm.2015.07.020DOI Listing
November 2015

Fatigue of Nitinol: The state-of-the-art and ongoing challenges.

J Mech Behav Biomed Mater 2015 Oct 16;50:228-54. Epub 2015 Jun 16.

Mechanics & Materials Consulting, LLC, 4447 Acrete Lane, Flagstaff, AZ 86004, USA.

Nitinol, a nearly equiatomic alloy of nickel and titanium, has been considered for a wide range of applications including medical and dental devices and implants as well as aerospace and automotive components and structures. The realistic loading condition in many of these applications is cyclic; therefore, fatigue is often the main failure mode for such components and structures. The fatigue behavior of Nitinol involves many more complexities compared with traditional metal alloys arising from its uniqueness in material properties such as superelasticity and shape memory effects. In this paper, a review of the present state-of-the-art on the fatigue behavior of superelastic Nitinol is presented. Various aspects of fatigue of Nitinol are discussed and microstructural effects are explained. Effects of material preparation and testing conditions are also reviewed. Finally, several conclusions are made and recommendations for future works are offered.
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http://dx.doi.org/10.1016/j.jmbbm.2015.06.010DOI Listing
October 2015