scholarly journals A Two-Scale Multi-Resolution Topologically Optimized Multi-Material Design of 3D Printed Craniofacial Bone Implants

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 101
Author(s):  
Jaejong Park ◽  
Tareq Zobaer ◽  
Alok Sutradhar
Keyword(s):  
Topology Optimization ◽  
Material Design ◽  
Implant Design ◽  
Patient Specific ◽  
Optimization Approach ◽  
Efficient Design ◽  
Physiological Loading ◽  
Maximum Stiffness ◽  
Good Potential ◽  
Craniofacial Defects

Bone replacement implants for craniofacial reconstruction require to provide an adequate structural foundation to withstand the physiological loading. With recent advances in 3D printing technology in place of bone grafts using autologous tissues, patient-specific additively manufactured implants are being established as suitable alternates. Since the stress distribution of these structures is complicated, efficient design techniques, such as topology optimization, can deliver optimized designs with enhanced functionality. In this work, a two-scale topology optimization approach is proposed that provides multi-material designs for both macrostructures and microstructures. In the first stage, a multi-resolution topology optimization approach is used to produce multi-material designs with maximum stiffness. Then, a microstructure with a desired property supplants the solid domain. This is beneficial for bone implant design since, in addition to imparting the desired functional property to the design, it also introduces porosity. To show the efficacy of the technique, four different large craniofacial defects due to maxillectomy are considered, and their respective implant designs with multi-materials are shown. These designs show good potential in developing patient-specific optimized designs suitable for additive manufacturing.

Coupled Multi-Material and Joint Topology Optimization: A Proof of Concept

2018 ◽  
Author(s):  
Vlad Florea ◽  
Vishrut Shah ◽  
Stephen Roper ◽  
Garrett Vierhout ◽  
Il Yong Kim
Keyword(s):  
Topology Optimization ◽  
Cost Effective ◽  
Material Design ◽  
Optimization Methods ◽  
Manufacturing Constraints ◽  
Proof Of Concept ◽  
Efficient Design ◽  
Engineering Costs ◽  
Increasing Demand ◽  
Material Layout

Over the past decade there has been an increasing demand for light-weight components for the automotive and aerospace industries. This has led to significant advancement in Topology Optimization methods, especially in developing new algorithms which can consider multi-material design. While Multi-Material Topology Optimization (MMTO) can be used to determine the optimum material layout and choice for a given engineering design problem, it fails to consider practical manufacturing constraints. One such constraint is the practical joining of multi-component designs. In this paper, a new method will be proposed for simultaneously performing MMTO and Joint Topology Optimization (JTO). This algorithm will use a serial approach to loop through the MMTO and JTO phases to obtain a truly optimum design which considers both aspects. A case study is performed on an automotive ladder frame chassis component as a proof of concept for the proposed approach. Two loops of the proposed process resulted in a reduction of components and in the number of joints used between them. This translates into a tangible improvement in the manufacturability of the MMTO design. Ultimately, being able to consider additional manufacturing constraints in the Topology Optimization process can greatly benefit research and development efforts. A better design is reached with fewer iterations, thus driving down engineering costs. Topology Optimization can help in determining a cost effective and efficient design which address existing structural design challenges.

A Multi-Scale Topology Optimization Approach for Optimal Macro-Layout and Local Grading of TPMS-Based Lattices

2021 ◽  
Author(s):  
Niclas Strömberg
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Local Density ◽  
Bulk Material ◽  
Transversely Isotropic ◽  
Benchmark Problems ◽  
Optimization Approach ◽  
Lattice Structures ◽  
Efficient Design ◽  
Multi Scale

Abstract The use of lattice structures in design for additive manufacturing has quickly emerged as a popular and efficient design alternative for creating innovative multifunctional lightweight solutions. In particular, the family of triply periodic minimal surfaces (TPMS) studied in detail by Schoen for generating frame-or shell-based lattice structures seems extra promising. In this paper a multi-scale topology optimization approach for optimal macro-layout and local grading of TPMS-based lattice structures is presented. The approach is formulated using two different density fields, one for identifying the macro-layout and another one for setting the local grading of the TPMS-based lattice. The macro density variable is governed by the standard SIMP formulation, but the local one defines the orthotropic elasticity of the element following material interpolation laws derived by numerical homogenization. Such laws are derived for frame- and shell-based Gyroid, G-prime and Schwarz-D lattices using transversely isotropic elasticity for the bulk material. A nice feature of the approach is that the lower and upper additive manufacturing limits on the local density of the TMPS-based lattices are included properly. The performance of the approach is excellent, and this is demonstrated by solving several three-dimensional benchmark problems, e.g., the optimal macro-layout and local grading of Schwarz-D lattice for the established GE-bracket is identified using the presented approach.

Ultrasonic Torsion Welding of Aging Resistant Al/CFRP Joints - Concepts, Mechanical and Microstructural Properties

2017 ◽  
Vol 742 ◽  
pp. 395-400 ◽  
Author(s):  
Florian Staab ◽  
Frank Balle ◽  
Johannes Born
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Materials Science ◽  
Dissimilar Materials ◽  
Material Design ◽  
Ultrasonic Welding ◽  
Fatigue Properties ◽  
Aviation Industry ◽  
Efficient Design ◽  
Engineering Structures

Multi-material-design offers high potential for weight saving and optimization of engineering structures but inherits challenges as well, especially robust joining methods and long-term properties of hybrid structures. The application of joining techniques like ultrasonic welding allows a very efficient design of multi-material-components to enable further use of material specific advantages and are superior concerning mechanical properties.The Institute of Materials Science and Engineering of the University of Kaiserslautern (WKK) has a long-time experience on ultrasonic welding of dissimilar materials, for example different kinds of CFRP, light metals, steels or even glasses and ceramics. The mechanical properties are mostly optimized by using ideal process parameters, determined through statistical test planning methods.This gained knowledge is now to be transferred to application in aviation industry in cooperation with CTC GmbH and Airbus Operations GmbH. Therefore aircraft-related materials are joined by ultrasonic welding. The applied process parameters are recorded and analyzed in detail to be interlinked with the resulting mechanical properties of the hybrid joints. Aircraft derived multi-material demonstrators will be designed, manufactured and characterized with respect to their monotonic and fatigue properties as well as their resistance to aging.

scholarly journals Surgical Advances in Osteosarcoma

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 388
Author(s):  
Marcus J. Brookes ◽  
Corey D. Chan ◽  
Bence Baljer ◽  
Sachin Wimalagunaratna ◽  
Timothy P. Crowley ◽  
...  
Keyword(s):  
Fluorescent Dyes ◽  
Imaging Techniques ◽  
Intraoperative Imaging ◽  
Survival Rates ◽  
Computer Navigation ◽  
Bone Cancer ◽  
Technical Difficulty ◽  
Implant Design ◽  
Patient Specific ◽  
Patient Specific Instruments

Osteosarcoma (OS) is the most common primary bone cancer in children and, unfortunately, is associated with poor survival rates. OS most commonly arises around the knee joint, and was traditionally treated with amputation until surgeons began to favour limb-preserving surgery in the 1990s. Whilst improving functional outcomes, this was not without problems, such as implant failure and limb length discrepancies. OS can also arise in areas such as the pelvis, spine, head, and neck, which creates additional technical difficulty given the anatomical complexity of the areas. We reviewed the literature and summarised the recent advances in OS surgery. Improvements have been made in many areas; developments in pre-operative imaging technology have allowed improved planning, whilst the ongoing development of intraoperative imaging techniques, such as fluorescent dyes, offer the possibility of improved surgical margins. Technological developments, such as computer navigation, patient specific instruments, and improved implant design similarly provide the opportunity to improve patient outcomes. Going forward, there are a number of promising avenues currently being pursued, such as targeted fluorescent dyes, robotics, and augmented reality, which bring the prospect of improving these outcomes further.

scholarly journals On the effect of antiresorptive drugs on the bone remodeling of the mandible after dental implantation: a mathematical model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mehran Ashrafi ◽  
Farzan Ghalichi ◽  
Behnam Mirzakouchaki ◽  
Manuel Doblare
Keyword(s):  
Mathematical Model ◽  
Bone Density ◽  
Bone Remodeling ◽  
Dental Implants ◽  
Implant Design ◽  
Patient Specific ◽  
Dental Implantation ◽  
Antiresorptive Agents ◽  
Antiresorptive Drugs

AbstractBone remodeling identifies the process of permanent bone change with new bone formation and old bone resorption. Understanding this process is essential in many applications, such as optimizing the treatment of diseases like osteoporosis, maintaining bone density in long-term periods of disuse, or assessing the long-term evolution of the bone surrounding prostheses after implantation. A particular case of study is the bone remodeling process after dental implantation. Despite the overall success of this type of implants, the increasing life expectancy in developed countries has boosted the demand for dental implants in patients with osteoporosis. Although several studies demonstrate a high success rate of dental implants in osteoporotic patients, it is also known that the healing time and the failure rate increase, necessitating the adoption of pharmacological measures to improve bone quality in those patients. However, the general efficacy of these antiresorptive drugs for osteoporotic patients is still controversial, requiring more experimental and clinical studies. In this work, we investigate the effect of different doses of several drugs, used nowadays in osteoporotic patients, on the evolution of bone density after dental implantation. With this aim, we use a pharmacokinetic–pharmacodynamic (PK/PD) mathematical model that includes the effect of antiresorptive drugs on the RANK/RANK-L/OPG pathway, as well as the mechano-chemical coupling with external mechanical loads. This mechano-PK/PD model is then used to analyze the evolution of bone in normal and osteoporotic mandibles after dental implantation with different drug dosages. We show that using antiresorptive agents such as bisphosphonates or denosumab increases bone density and the associated mechanical properties, but at the same time, it also increases bone brittleness. We conclude that, despite the many limitations of these very complex models, the one presented here is capable of predicting qualitatively the evolution of some of the main biological and chemical variables associated with the process of bone remodeling in patients receiving drugs for osteoporosis, so it could be used to optimize dental implant design and coating for osteoporotic patients, as well as the drug dosage protocol for patient-specific treatments.

An Evolutionary Multi-Objective Optimization Approach to the Topology Optimization of Auxetic Structures

2002 ◽  
Author(s):  
Ashraf O. Nassef
Keyword(s):  
Topology Optimization ◽  
Elastic Modulus ◽  
Finite Elements ◽  
Multiobjective Optimization ◽  
Poisson Ratio ◽  
Optimization Approach ◽  
Multi Objective Optimization ◽  
Finite Elements Analysis ◽  
Multi Objective ◽  
Auxetic Structures

Auxetic structures are ones, which exhibit an in-plane negative Poisson ratio behavior. Such structures can be obtained by specially designed honeycombs or by specially designed composites. The design of such honeycombs and composites has been tackled using a combination of optimization and finite elements analysis. Since, there is a tradeoff between the Poisson ratio of such structures and their elastic modulus, it might not be possible to attain a desired value for both properties simultaneously. The presented work approaches the problem using evolutionary multiobjective optimization to produce several designs rather than one. The algorithm provides the designs that lie on the tradeoff frontier between both properties.

scholarly journals A new stress-based topology optimization approach for finding flexible structures

2021 ◽  
Author(s):  
Martin Noack ◽  
Arnold Kühhorn ◽  
Markus Kober ◽  
Matthias Firl
Keyword(s):  
Topology Optimization ◽  
Stress State ◽  
Design Space ◽  
Flexible Structures ◽  
Optimization Approach ◽  
Principal Stresses ◽  
Output Displacement ◽  
Design Concepts ◽  
Flexible Designs ◽  
Gauss Points

AbstractThis paper presents a new FE-based stress-related topology optimization approach for finding bending governed flexible designs. Thereby, the knowledge about an output displacement or force as well as the detailed mounting position is not necessary for the application. The newly developed objective function makes use of the varying stress distribution in the cross section of flexible structures. Hence, each element of the design space must be evaluated with respect to its stress state. Therefore, the method prefers elements experiencing a bending or shear load over elements which are mainly subjected to membrane stresses. In order to determine the stress state of the elements, we use the principal stresses at the Gauss points. For demonstrating the feasibility of the new topology optimization approach, three academic examples are presented and discussed. As a result, the developed sensitivity-based algorithm is able to find usable flexible design concepts with a nearly discrete 0 − 1 density distribution for these examples.

Synthesis and Numerical Analysis of Compliant devices – A Topology Optimization Approach for Mechanisms and Robotic Systems

2021 ◽  
Author(s):  
Premanand Sathyanarayanamurthi ◽  
ARUNKUMAR GOPAL
Keyword(s):  
Topology Optimization ◽  
Optimization Design ◽  
Rectangular Domain ◽  
Dynamic State ◽  
Optimization Approach ◽  
Design And Development ◽  
Design Synthesis ◽  
Final Destination ◽  
Prototype Development ◽  
External Forces

Abstract The Topology Optimization design invariably shall be used in various applications like Aerojet designs, Aircraft Engineering designs and innovative systems for improving the efficiency of structure. The paper emphasizes more on general Topology Optimization design for a rectangular domain. The domain numerically analyzed with defined geometry setting and defined boundary conditions for finding the Stress and displacement. In this Topology Optimization Design synthesis, the result is suitable volume and mass reduction in the Aerojet application parts which further can be taken for Prototype development in 3D printing and experimentally test with safety characteristics and compares Objective functions chosen for design and development. The design can be used for other various automotive and aerospace devices based on deformation level and application of external forces. The Final destination of this design and development ends with passing Fatigue Endurance test cycle test pass condition in Aerojet and automotive vehicles in static and dynamic state.

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