Imaging-based customization of lattice structures for biomedical applications

2019 ◽  
Author(s):  
◽  
Xuewei Ma
Keyword(s):  
Joint Replacement ◽  
Mechanical Performance ◽  
Stress Shielding ◽  
Digital Design ◽  
Lattice Structures ◽  
Biological Fixation ◽  
Joint Reconstruction ◽  
Lattice Design ◽  
Design Variables ◽  
Graded Properties

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Synovial joints can provide movement and articulation, however, with overuse, aging, and trauma, joint replacement surgeries may be needed. Commercially available joint reconstruction implants have undergone great improvement during the past decades. Nevertheless, existing solutions using available implant designs and materials have limitations that lead to potential failure, particularly with young active patients. Bone cement and stress shielding have been identified as the major reasons for premature artificial joint failures. A breakdown of the cement may happen and revision surgery may be needed because of the aseptic loosening. The stress shielding problem is caused by the significant mismatch of stiffness properties between the patient trabecular bones and metallic implant materials for joint replacement surgeries. This research introduces a novel method to develop customized lattice structures with graded properties according to the mechanical properties derived from clinical Computed Tomography (CT) scan of the bone. Various lattice design variables are being analyzed for their effects on mechanical performance and geometrical features needed for biological fixation and manufacturability. The introduced mathematical models and techniques in the proposed work facilitate generic direct digital design and manufacturing of effective customized lattice structures with graded properties for joint reconstruction applications.

scholarly journals A Further Analysis on Ti6Al4V Lattice Structures Manufactured by Selective Laser Melting

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Saverio Maietta ◽  
Antonio Gloria ◽  
Giovanni Improta ◽  
Maria Richetta ◽  
Roberto De Santis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mass Transport ◽  
Selective Laser Melting ◽  
Mechanical Performance ◽  
Stress Shielding ◽  
Lattice Structures ◽  
Laser Melting ◽  
Tissue Ingrowth ◽  
Architectural Features ◽  
Bone Atrophy

Mechanical and architectural features play an important role in designing biomedical devices. The use of materials (i.e., Ti6Al4V) with Young’s modulus higher than those of natural tissues generally cause stress shielding effects, bone atrophy, and implant loosening. However, porous devices may be designed to reduce the implant stiffness and, consequently, to improve its stability by promoting tissue ingrowth. If porosity increases, mass transport properties, which are crucial for cell behavior and tissue ingrowth, increase, whereas mechanical properties decrease. As reported in the literature, it is always possible to tailor mass transport and mechanical properties of additively manufactured structures by varying the architectural features, as well as pore shape and size. Even though many studies have already been made on different porous structures with controlled morphology, the aim of current study was to provide only a further analysis on Ti6Al4V lattice structures manufactured by selective laser melting. Experimental and theoretical analyses also demonstrated the possibility to vary the architectural features, pore size, and geometry, without dramatically altering the mechanical performance of the structure.

scholarly journals Low Thermal Expansion Machine Frame Designs Using Lattice Structures

2021 ◽  
Vol 11 (19) ◽  
pp. 9135
Author(s):  
Poom Juasiripukdee ◽  
Ian Maskery ◽  
Ian Ashcroft ◽  
Richard Leach
Keyword(s):  
Thermal Expansion ◽  
Mechanical Performance ◽  
Coefficient Of Thermal Expansion ◽  
Lattice Structure ◽  
Numerical Models ◽  
Outer Part ◽  
Lattice Structures ◽  
Lattice Design ◽  
Low Thermal Expansion ◽  
Nylon 12

In this work, we investigated tessellating cellular (or lattice) structures for use in a low thermal expansion machine frame. We proposed a concept for a lattice structure with tailorable effective coefficient of thermal expansion (CTE). The design is an assembly of two parts: a lattice outer part and a cylindrical inner part, which are made of homogenous materials with different positive CTEs. Several lattice design variations were investigated and their thermal and mechanical performance analysed using a finite element method. Our numerical models showed that a lattice design using Nylon 12 and ultra-high molecular weight polyethylene could yield an effective in-plane CTE of 1 × 10−9 K−1 (cf. 109 × 10−6 K−1 for solid Nylon 12). This paper showed that the combination of design optimisation and additive manufacturing can be used to achieve low CTE structures and, therefore, low thermal expansion machine frames of a few tens of centimetres in height.

Multi-objective design optimization of additively manufactured lattice structures for improved energy absorption performance

2021 ◽  
pp. 095440622199554
Author(s):  
Recep M Gorguluarslan
Keyword(s):  
Energy Absorption ◽  
Response Surfaces ◽  
Optimization Process ◽  
Truss Optimization ◽  
Size Optimization ◽  
Lattice Structures ◽  
Multi Objective ◽  
Lattice Design ◽  
Highly Nonlinear ◽  
Absorption Performance

This paper aims to improve the energy absorption performance of stiffness-optimized lattice structures by utilizing a multi-objective surrogate-based size optimization that considers the additive manufacturing (AM) constraints such as the minimum printable size. A truss optimization is first utilized at the unit cell level under static compressive loads for stiffness maximization and two optimized lattice configurations called the Face-Body Centered Cubic (FBCC) lattice and the Octet Cubic (OC) are obtained. A multi-objective size optimization process is then carried out to improve the energy absorption capabilities of those lattice designs using non-linear compression simulations with Nylon12 material to be fabricated by the Multi Jet Fusion (MJF) AM process. Thin plate spline (TPS) interpolation method is found to produce very high accuracy as the surrogate model to predict the highly nonlinear response surfaces of energy absorption objectives in the optimization. Compared to the lattice designs with uniform strut diameters, by using the optimization process, the maximum energy absorption efficiency ( EAEm) and the crush stress efficiency ( CSE) of the OC lattice design are further improved up to 33% and 37%, respectively. The FBCC lattice design is also found to have superior EAEm performance compared to the existing lattice types considered for fabricating by the MJF process in the literature.

A Proof of Concept Study of the Mechanical Behavior of Lattice Structures Used to Design a Shoulder Hemi-Prosthesis

2021 ◽  
Author(s):  
Marinela Peto ◽  
Oscar Aguilar-Rosas ◽  
Erick Erick Ramirez-Cedillo ◽  
Moises Jimenez ◽  
Adriana Hernandez ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Cell Attachment ◽  
Lattice Structure ◽  
Material Model ◽  
Patient Specific ◽  
Hexagonal Prism ◽  
Lattice Structures ◽  
Proof Of Concept

Abstract Lattice structures offer great benefits when employed in medical implants for cell attachment and growth (osseointegration), minimization of stress shielding phenomena, and weight reduction. This study is focused on a proof of concept for developing a generic shoulder hemi-prosthesis, from a patient-specific case of a 46 years old male with a tumor on the upper part of his humerus. A personalized biomodel was designed and a lattice structure was integrated in its middle portion, to lighten weight without affecting humerus’ mechanical response. To select the most appropriate lattice structure, three different configurations were initially tested: Tetrahedral Vertex Centroid (TVC), Hexagonal Prism Vertex Centroid (HPVC), and Cubic Diamond (CD). They were fabricated in resin by digital light processing and its mechanical behavior was studied via compression testing and finite element modeling (FEM). The selected structure according to the results was the HPVC, which was integrated in a digital twin of the biomodel to validate its mechanical performance through FEM but substituting the bone material model with a biocompatible titanium alloy (Ti6Al4V) suitable for prostheses fabrication. Results of the simulation showed acceptable levels of Von Mises stresses (325 MPa max.), below the elastic limit of the titanium alloys, and a better response (52 MPa max.) in a model with equivalent elastic properties, with stress performance in the same order of magnitude than the showed in bone’s material model.

scholarly journals Electron Beam Melting of Ti-6Al-4V Lattice Structures; Correlation between Post Heat Treatment and Mechanical Properties

2021 ◽  
Author(s):  
Giuseppe Del Guercio ◽  
Manuela Galati ◽  
Abdollah Saboori
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Computer Aided Design ◽  
Mechanical Performance ◽  
Industrial Applications ◽  
Heat Treatments ◽  
Layer By Layer ◽  
Lattice Structures ◽  
Heat Treated ◽  
Aided Design

Abstract Additive Manufacturing processes are considered advanced manufacturing methods. It would be possible to produce complex shape components from a Computer-Aided Design model in a layer-by-layer manner. Lattice structures as one of the complex geometries could attract lots of attention for both medical and industrial applications. In these structures, besides cell size and cell type, the microstructure of lattice structures can play a key role in these structures' mechanical performance. On the other hand, heat treatment has a significant influence on the mechanical properties of the material. Therefore, in this work, the effect of the heat treatments on the microstructure and mechanical behaviour of Ti-6Al-4V lattice structures manufactured by EBM was analyzed. The main mechanical properties were compared with the Ashby and Gibson model. It is very interesting to notice that a more homogeneous failure mode was found for the heat-treated samples. The structures' relative density was the main factor influencing their mechanical performance of the heat-treated samples. It is also found that the heat treatments were able to preserve the stiffness and the compressive strength of the lattice structures. Besides, an increment of both the elongation at failure and the absorbed energy was obtained after the heat treatments. Microstructure analysis of the heat-treated samples confirms the increment of ductility of the heat-treated samples with respect to the as-built one.

scholarly journals EXPERIMENTAL INVESTIGATION AND SIMULATION OF 3D-PRINTED LATTICE STRUCTURES

2019 ◽  
Vol 25 ◽  
pp. 52-57
Author(s):  
Eva Heiml ◽  
Anna Kalteis ◽  
Zoltan Major
Keyword(s):  
Mechanical Performance ◽  
Bulk Material ◽  
Deformation Behaviour ◽  
Lightweight Design ◽  
Thermoplastic Polyurethane ◽  
Selective Laser Sintering ◽  
Structural Performance ◽  
Lattice Structures ◽  
3D Printed ◽  
Manufacturing Techniques

Lattice structures are currently of high interest, especially for lightweight design. They generally have better structural performance per weight than parts made of bulk material. With conventional manufacturing techniques they are difficult to produce, but with additive manufacturing (AM) fabricationisfeasible. To better understand their behaviour under various loading conditions two lattice structures in different configurations were observed. For each structure three different test specimens were designed and manufactured using selective laser sintering (SLS). To investigate the mechanical performance under large deformations the specimens were made of a thermoplastic polyurethane(TPU), which shows a hyperelastic material behaviour. Beside the experimental observations also finite element analyses (FEA) were conducted to investigate the deformation behaviour in more detail.

The Effect of Micro Grooving on Goat Total Knee Replacement: A Finite Element Study

2020 ◽  
Author(s):  
Morshed Khandaker ◽  
Onur Can Kalay ◽  
Fatih Karpat ◽  
Amgad Haleem ◽  
Wendy Williams ◽  
...  
Keyword(s):  
Finite Element ◽  
Total Knee Replacement ◽  
Knee Replacement ◽  
Joint Replacement ◽  
Mechanical Performance ◽  
The United States ◽  
Cement Interface ◽  
Bonding Failure ◽  
Total Knee ◽  
Joint Prostheses

Abstract A method to improve the mechanical fixation of a total knee replacement (TKR) implant is clinically important and is the purpose of this study. More than one million joint replacement procedures are performed in people each year in the United States, and experts predict the number to increase six-fold by the year 2030. Whether cemented or uncemented, joint prostheses may destabilize over time and necessitate revision. Approximately 40,000 hip arthroplasty surgeries have to be revised each year and the rate is expected to increase by approximately 140% (and by 600% for total knee replacement) over the next 25 years. In veterinary surgery, joint replacement has a long history and the phenomenon of surgical revision is also well recognized. For the betterment of both people and animals, improving the longevity of arthroplasty devices is of the utmost clinical importance, and towards that end, several strategies are under investigation. One approach that we explore in the present research is to improve the biomechanical performance of cemented implant systems by altering the implant surface architecture in a way that facilitates its cement bonding capacity. Beginning with the Charnley system, early femoral stems were polished smooth, but a number of subsequent designs have featured a roughened surface — created with bead or grit blasting — to improve cement bonding. Failure at the implant-cement interface remains an issue with these newer designs, leading us to explore in this present research an alternate, novel approach to surface alteration — specifically, laser microgrooving. This study used various microgrooves architectures that is feasible using a laser micromachining process on a tibia tray (TT) for the goat TKR. Developing the laser microgrooving (LM) procedure, we hypothesized feasibility in producing parallel microgrooves of precise dimensions and spacing on both flat and round metallic surfaces. We further hypothesized that laser microgrooving would increase surface area and roughness of the cement interface of test metallic implants and that such would translate into an improved acute mechanical performance as assessed in vitro under both static and cyclic loads. The objective was to develop a computational model to determine the effect of LIM on the tibial tray to the mechanical stimuli distributions from implant to bone using the finite element method. This study designed goat TT 3D solid model from a computer topography (CT) images, out of which three different laser microgrooves were engraved on TT sample by varying depth, height and space between two adjacent grooves. The simulation test results concluded that microgrooves acchitecures positively influence microstrain behavior around the implant/bone interfaces. There is a higher amount of strain observed for microgroove implant/bone samples compared to non-groove implant/bone samples. Thus, the laser-induced microgrooves have the potential to be used clinically in TKR components.

scholarly journals Substructure-Based Topology Optimization for Symmetric Hierarchical Lattice Structures

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 678
Author(s):  
Zijun Wu ◽  
Renbin Xiao
Keyword(s):  
Topology Optimization ◽  
High Efficiency ◽  
Spline Interpolation ◽  
Optimization Method ◽  
Optimality Criteria ◽  
Lattice Structures ◽  
Hierarchical Lattice ◽  
B Spline ◽  
Design Variables ◽  
Optimality Criteria Method

This work presents a topology optimization method for symmetric hierarchical lattice structures with substructuring. In this method, we define two types of symmetric lattice substructures, each of which contains many finite elements. By controlling the materials distribution of these elements, the configuration of substructure can be changed. And then each substructure is condensed into a super-element. A surrogate model based on a series of super-elements can be built using the cubic B-spline interpolation. Here, the relative density of substructure is set as the design variable. The optimality criteria method is used for the updating of design variables on two scales. In the process of topology optimization, the symmetry of microstructure is determined by self-defined microstructure configuration, while the symmetry of macro structure is determined by boundary conditions. In this proposed method, because of the educing number of degree of freedoms on macrostructure, the proposed method has high efficiency in optimization. Numerical examples show that both the size and the number of substructures have essential influences on macro structure, indicating the effectiveness of the presented method.

scholarly journals Digital design and nonlinear simulation for additive manufacturing of soft lattice structures

2019 ◽  
Vol 25 ◽  
pp. 39-49 ◽  
Author(s):  
O. Weeger ◽  
N. Boddeti ◽  
S.-K. Yeung ◽  
S. Kaijima ◽  
M.L. Dunn
Keyword(s):  
Additive Manufacturing ◽  
Digital Design ◽  
Lattice Structures ◽  
Nonlinear Simulation
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