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Optimal Design of Materials and Structures
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Optimal Design of Materials and Structures

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Simulation and Design".

Deadline for manuscript submissions: closed (30 October 2019) | Viewed by 52372

Special Issue Editors

Prof. Dr. Aleksander Muc

E-Mail Website
Guest Editor
Institute of Machine Design, Cracow University of Technology, Warszawska 24, 31-155 Cracow, Poland
Interests: composite materials; numerical methods; experimental methods (thermography, SHM, DIC); static and fatigue damage of materials and constructions; plated and shell structures; optimization algorithms; vibrations; nanomechanics and nanostructures; machine design; mechanical behavior of polymers; flutter problems
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Jerzy A. Sładek

E-Mail Website
Guest Editor
Laboratory of Coordinate Metrology, Faculty of Mechanical Engineering, Cracow University of Technology, Krakow, Poland
Interests: mechanical engineering; coordinate metrology and its applications in production engineering; micro and nano dimensional metrology; calibration methods for coordinate systems; fringe optics systems and photogrammetry; metrological aspects of reverse engineering; metrology in industrial design and Industry 4.0; quality engineering; quality management systems
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Researchers are already applying optimization methods and the mechanics of structural elements in series, from the use of mechanical models to the description of objective functions, and finally to quantify the best solutions with the help of various optimization algorithms. However, the integration of these two fields combined with factors taking into account technological aspects and the structure of macro-, micro- and nanomaterials into an optimal design of materials holds even greater potential benefits in optimizing results. It is a truly `high-tech' field, requiring advanced computer facilities and computational methods along with supervisory instrumentation and methods. The understanding and application of the optimal design of materials and constructions is a truly interdisciplinary endeavor. This work is an attempt to bring together recent developments in the field—from materials science, mechanics, optimization and engineering manufacturing including quality control and measurement techniques—into a single volume. An isotropic or anisotropic material cannot be treated as an existing material structure that can be directly utilized by designers. This is a structure that has to be shaped, tailored and inspected in a proper way in a design and manufacturing and quality control processes in order to obtain the appropriate performance of the designed constructions, at the same time meeting the multidisciplinary requirements and/or specifications. For engineering structures, the determination of optimal solutions by means of material design is more reliable, efficient and necessary in modern science and using modern techniques. The aim of this Special Issue is to explain and prove that seemingly different structural and manufacturing process optimization problems in the area of the material design can be solved in a unified, compact manner.

The forthcoming Special Issue of Materials aims to follow new advances in the attractive field of optimal design in engineering. It is our pleasure to invite you to contribute your research article, communication, or review to this Special Issue.

Prof. Muc Aleksander
Prof. Jerzy A. Sładek
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Optimal design of macro-, micro- and nanomaterials
  • Design of isotropic and anisotropic properties
  • Optimal design of structures subjected to static and fatigue loads
  • Quality control in design and manufacturing of materials
  • Optimization algorithms used in material and structural design
  • Influence of technological process on optimal material design
  • Numerical modelling of materials and structures in optimal design (finite element and finite volume methods)
  • Numerical modelling of technological and measurement processes in design and manufacturing of materials

Published Papers (15 papers)

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Research

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12 pages, 3388 KiB  
Article
Analyzing Uncertainty of an Ankle Joint Model with Genetic Algorithm
by Adam Ciszkiewicz
Materials 2020, 13(5), 1175; https://doi.org/10.3390/ma13051175 - 06 Mar 2020
Cited by 6 | Viewed by 1829
Abstract
Recent studies in biomechanical modeling suggest a paradigm shift, in which the parameters of biomechanical models would no longer treated as fixed values but as random variables with, often unknown, distributions. In turn, novel and efficient numerical methods will be required to handle [...] Read more.
Recent studies in biomechanical modeling suggest a paradigm shift, in which the parameters of biomechanical models would no longer treated as fixed values but as random variables with, often unknown, distributions. In turn, novel and efficient numerical methods will be required to handle such complicated modeling problems. The main aim of this study was to introduce and verify genetic algorithm for analyzing uncertainty in biomechanical modeling. The idea of the method was to encode two adversarial models within one decision variable vector. These structures would then be concurrently optimized with the objective being the maximization of the difference between their outputs. The approach, albeit expensive numerically, offered a general formulation of the uncertainty analysis, which did not constrain the search space. The second aim of the study was to apply the proposed procedure to analyze the uncertainty of an ankle joint model with 43 parameters and flexible links. The bounds on geometrical and material parameters of the model were set to 0.50 mm and 5.00% respectively. The results obtained from the analysis were unexpected. The two obtained adversarial structures were almost visually indistinguishable and differed up to 38.52% in their angular displacements. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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13 pages, 3645 KiB  
Article
Tribological Characteristic of a Ring Seal with Graphite Filler
by Wojciech Szczypinski-Sala and Janusz Lubas
Materials 2020, 13(2), 311; https://doi.org/10.3390/ma13020311 - 09 Jan 2020
Cited by 15 | Viewed by 2578
Abstract
This paper presents the outcome of the measurement of the tribological characteristic of O-ring seals in the event of operating in conditions with a lack of lubrication. The measurement was carried out on a seal and rod model. The measurement was carried out [...] Read more.
This paper presents the outcome of the measurement of the tribological characteristic of O-ring seals in the event of operating in conditions with a lack of lubrication. The measurement was carried out on a seal and rod model. The measurement was carried out during the condition of the round cross-section seal sliding on the surface of the piston rod. We analyzed how the friction force during rod movement, which resulted from the cooperation of the sliding nod and the rod, was changing. The experiment was conducted for various rubber materials. The aim of the research was to evaluate the friction reducing capability of graphite in rubbers of commercial sealing parts. Typical materials used for the seal and the materials, which contained the filler in the form of graphite powder, were compared. Synthetic graphite powder with a particle size of 1–2 µm was applied, and nitrile rubber (NBR) and fluoroelastomer (FKM) were compared as typical materials for O-ring seals. In the case of the two tested materials, the addition of graphite powder had an influence on the decrease in the friction force. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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15 pages, 4478 KiB  
Article
Optimization of Functionally Graded Structural Members by Means of New Effective Properties Estimation Method
by Anna Wiśniewska and Halina Egner
Materials 2019, 12(19), 3139; https://doi.org/10.3390/ma12193139 - 26 Sep 2019
Cited by 5 | Viewed by 1842
Abstract
An innovative method of effective composite mechanical properties estimation is applied to optimize the distribution of reinforcement in a functionally graded structural element. The concept is based on the assumption of the mechanical equivalence between two configurations: The real heterogeneous composite configuration and [...] Read more.
An innovative method of effective composite mechanical properties estimation is applied to optimize the distribution of reinforcement in a functionally graded structural element. The concept is based on the assumption of the mechanical equivalence between two configurations: The real heterogeneous composite configuration and the fictitious quasi-homogeneous one. It allows to obtain the analytical formulae describing the dependence of the effective elastic composite properties on the volume fraction of reinforcing inclusions. As an example of application, a circular bar subjected to torsion is considered. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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14 pages, 1700 KiB  
Article
The Use of Biodrying to Prevent Self-Heating of Alternative Fuel
by Teresa Gajewska, Mateusz Malinowski and Maciej Szkoda
Materials 2019, 12(18), 3039; https://doi.org/10.3390/ma12183039 - 19 Sep 2019
Cited by 11 | Viewed by 2676
Abstract
Alternative fuels (refuse-derived fuels—RDF) have been a substitute for fossil fuels in cement production for many years. RDF are produced from various materials characterized by high calorific value. Due to the possibility of self-ignition in the pile of stored alternative fuel, treatments are [...] Read more.
Alternative fuels (refuse-derived fuels—RDF) have been a substitute for fossil fuels in cement production for many years. RDF are produced from various materials characterized by high calorific value. Due to the possibility of self-ignition in the pile of stored alternative fuel, treatments are carried out to help protect entrepreneurs against material losses and employees against loss of health or life. The objective of the research was to assess the impact of alternative fuel biodrying on the ability to self-heat this material. Three variants of materials (alternative fuel produced on the basis of mixed municipal solid waste (MSW) and on the basis of bulky waste (mainly varnished wood and textiles) and residues from selective collection waste (mainly plastics and tires) were adopted for the analysis. The novelty of the proposed solution consists in processing the analyzed materials inside the innovative ecological waste apparatus bioreactor (EWA), which results in increased process efficiency and shortening its duration. The passive thermography technique was used to assess the impact of alternative fuel biodrying on the decrease in the self-heating ability of RDF. As a result of the conducted analyses, it was clear that the biodrying process inhibited the self-heating of alternative fuel. The temperature of the stored fuel reached over 60 °C before the biodrying process. However, after the biodrying process, the maximum temperatures in each of the variants were about 30 °C, which indicates a decrease in the activity of microorganisms and the lack of self-ignition risk. The maximum temperatures obtained (>71 °C), the time to reach them (≈4 h), and the duration of the thermophilic phase (≈65 h) are much shorter than in the studies of other authors, where the duration of the thermophilic phase was over 80 h. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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16 pages, 3568 KiB  
Article
Optimal Design of pH-neutral Geopolymer Foams for Their Use in Ecological Plant Cultivation Systems
by Magdalena Szechyńska-Hebda, Joanna Marczyk, Celina Ziejewska, Natalia Hordyńska, Janusz Mikuła and Marek Hebda
Materials 2019, 12(18), 2999; https://doi.org/10.3390/ma12182999 - 16 Sep 2019
Cited by 32 | Viewed by 4211
Abstract
We have calculated that with the world population projected to increase from 7.5 billion in 2017 to 9.8 in 2050, the next generation (within 33 years) will produce 12,000–13,000 Mt of plastic, and that the yearly consumption will reach 37–40 kilos of plastic [...] Read more.
We have calculated that with the world population projected to increase from 7.5 billion in 2017 to 9.8 in 2050, the next generation (within 33 years) will produce 12,000–13,000 Mt of plastic, and that the yearly consumption will reach 37–40 kilos of plastic per person worldwide. One of the branches of the plastics industry is the production of plastics for agriculture e.g., seed trays and pots. In this paper, novel metakaolin-based geopolymer composites reinforced with cellulosic fibres are presented as an alternative to plastic pots. Materials can be dedicated to agricultural applications, provided they have neutral properties, however, geopolymer paste and its final products have high pH. Therefore, a two-step protocol of neutralisation of the geopolymer foam pots was optimised and implemented. The strength of the geopolymer samples was lower when foams were neutralised. The reinforcement of geopolymers with cellulose clearly prevented the reduction of mechanical properties after neutralisation, which was correlated with the lower volume of pores in the foam and with the cellulose chemical properties. Both, neutralisation and reinforcement with cellulose can also eliminate an efflorescence. Significantly increased plant growth was found in geopolymer pots in comparison to plastic pots. The cellulose in geopolymers resulted in better adsorption and slower desorption of minerals during fertilisation. This effect could also be associated with a lower number of large pores in the presence of cellulose fibres in pots, and thus more stable pore filling and better protection of internal surface interactions. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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17 pages, 6673 KiB  
Article
Optimized Dental Implant Fixture Design for the Desirable Stress Distribution in the Surrounding Bone Region: A Biomechanical Analysis
by Won Hyeon Kim, Jae-Chang Lee, Dohyung Lim, Young-Ku Heo, Eun-Sung Song, Young-Jun Lim and Bongju Kim
Materials 2019, 12(17), 2749; https://doi.org/10.3390/ma12172749 - 27 Aug 2019
Cited by 19 | Viewed by 8243
Abstract
The initial stability of a dental implant is known to be an indicator of osseointegration at immediate loading upon insertion. Implant designs have a fundamental role in the initial stability. Although new designs with advanced surface technology have been suggested for the initial [...] Read more.
The initial stability of a dental implant is known to be an indicator of osseointegration at immediate loading upon insertion. Implant designs have a fundamental role in the initial stability. Although new designs with advanced surface technology have been suggested for the initial stability of implant systems, verification is not simple because of various assessment factors. Our study focused on comparing the initial stability between two different implant systems via design aspects. A simulated model corresponding to the first molar derived from the mandibular bone was constructed. Biomechanical characteristics between the two models were compared by finite element analysis (FEA). Mechanical testing was also performed to derive the maximum loads for the two implant systems. CMI IS-III active (IS-III) had a more desirable stress distribution than CMI IS-II active (IS-II) in the surrounding bone region. Moreover, IS-III decreased the stress transfer to the nerve under the axial loading direction more than IS-II. Changes of implant design did not affect the maximum load. Our analyses suggest that the optimized design (IS-III), which has a bigger bone volume without loss of initial fixation, may minimize the bone damage during fixture insertion and we expect greater effectiveness in older patients. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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15 pages, 2472 KiB  
Article
A Planar Model of an Ankle Joint with Optimized Material Parameters and Hertzian Contact Pairs
by Aleksandra Borucka and Adam Ciszkiewicz
Materials 2019, 12(16), 2621; https://doi.org/10.3390/ma12162621 - 17 Aug 2019
Cited by 6 | Viewed by 2987
Abstract
The ankle is one of the most complicated joints in the human body. Its features a plethora of elements with complex behavior. Their functions could be better understood using a planar model of the joint with low parameter count and low numerical complexity. [...] Read more.
The ankle is one of the most complicated joints in the human body. Its features a plethora of elements with complex behavior. Their functions could be better understood using a planar model of the joint with low parameter count and low numerical complexity. In this study, an accurate planar model of the ankle with optimized material parameters was presented. In order to obtain the model, we proposed an optimizational approach, which fine-tuned the material parameters of two-dimensional links substituting three-dimensional ligaments of the ankle. Furthermore, the cartilage in the model was replaced with Hertzian contact pairs. The model was solved in statics under moment loads up to 5 Nm. The obtained results showed that the structure exhibited angular displacements in the range of the ankle joint and that their range was higher in dorsiflexion than plantarflexion. The structure also displayed a characteristic ramp up of the angular stiffness. The results obtained from the optimized model were in accordance with the experimental results for the ankle. Therefore, the proposed method for fine-tuning the material parameters of its links could be considered viable. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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18 pages, 10001 KiB  
Article
The Durability of an Organic–Inorganic Sol–Gel Interlayer in Al-GFRP-CFRP Laminates in a Saline Environment
by Barbara Surowska, Monika Ostapiuk, Patryk Jakubczak and Magda Droździel
Materials 2019, 12(15), 2362; https://doi.org/10.3390/ma12152362 - 25 Jul 2019
Cited by 11 | Viewed by 3061
Abstract
The aim of the study was to assess the selected properties of a hybrid organic–inorganic silane sol–gel coating (HSG) used in hybrid fiber metal laminates (FML) in a corrosion environment. The HSG coating on the aluminum alloy was produced using 3M™ AC130-2 formulation [...] Read more.
The aim of the study was to assess the selected properties of a hybrid organic–inorganic silane sol–gel coating (HSG) used in hybrid fiber metal laminates (FML) in a corrosion environment. The HSG coating on the aluminum alloy was produced using 3M™ AC130-2 formulation consisting of 3-glycidoxypropyl-trimethoxysilane (GPTMS) and tetra-n-propoxyzirconium (zirconium(IV) propoxide) (TPOZ). Laminates consisted of aluminum alloy AA2024-T3 sheets, with carbon fiber reinforced polymers (CFRPs) and a glass fiber reinforced metal–composite structure (GFRP). Potentiodynamic and polarization curve and impedance (EIS) tests were carried out on HSG at ambient temperatures after 1 h and 150 h of soaking. Neutral 0.5 M NaCl and 0.8 M NaCl solutions were used for open circuit potential (OCP) and potentiodynamic tests, and 0.5 NaCl was used for the EIS test. A neutral salt spray (NSS) test was applied to laminates with a 12 week exposure period. The results obtained revealed that the HSG coating did not provide sufficient protection against corrosion of the aluminum alloy in direct contact with an aggressive environment but was effective as an interlayer. Local aluminum sheet perforation did not lead to delamination at the metal–composite interface regardless of the type or configuration of the composite. This confirms the durability of HSG used in FMLs. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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14 pages, 4292 KiB  
Article
Fuzzy Multi-SVR Learning Model for Reliability-Based Design Optimization of Turbine Blades
by Chun-Yi Zhang, Ze Wang, Cheng-Wei Fei, Zhe-Shan Yuan, Jing-Shan Wei and Wen-Zhong Tang
Materials 2019, 12(15), 2341; https://doi.org/10.3390/ma12152341 - 24 Jul 2019
Cited by 23 | Viewed by 2887
Abstract
The effectiveness of a model is the key factor of influencing the reliability-based design optimization (RBDO) of multi-failure turbine blades in the power system. A machine learning-based RBDO approach, called fuzzy multi-SVR learning method, was proposed by absorbing the strengths of fuzzy theory, [...] Read more.
The effectiveness of a model is the key factor of influencing the reliability-based design optimization (RBDO) of multi-failure turbine blades in the power system. A machine learning-based RBDO approach, called fuzzy multi-SVR learning method, was proposed by absorbing the strengths of fuzzy theory, support vector machine of regression (SVR), and multi-response surface method. The model of fuzzy multi-SVR learning method was established by adopting artificial bee colony algorithm to optimize the parameters of SVR models and considering the fuzziness of constraints based on fuzzy theory, in respect of the basic thought of multi-response surface method. The RBDO model and procedure with fuzzy multi-SVR learning method were then resolved and designed by multi-objective genetic algorithm. Lastly, the fuzzy RBDO of a turbine blade with multi-failure modes was performed regarding the design parameters of rotor speed, temperature, and aerodynamic pressure, and the design objectives of blade stress, strain, and deformation, and the fuzzy constraints of reliability degree and boundary conditions, as well. It is revealed (1) the stress and deformation of turbine blade are reduced by 92.38 MPa and 0.09838 mm, respectively. (2) The comprehensive reliability degree of the blade was improved by 3.45% from 95.4% to 98.85%. (3) It is verified that the fuzzy multi-SVR learning method is workable for the fuzzy RBDO of complex structures just like a multi-failure blade with high modeling precision, as well as high optimization, efficiency, and accuracy. The efforts of this study open a new research way, i.e., machine learning-based RBDO, for the RBDO of multi-failure structures, which expands the application of machine learning methods, and enriches the mechanical reliability design method and theory as well. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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13 pages, 2724 KiB  
Article
Structural and Material Optimization for Automatic Synthesis of Spine-Segment Mechanisms for Humanoid Robots with Custom Stiffness Profiles
by Adam Ciszkiewicz and Grzegorz Milewski
Materials 2019, 12(12), 1982; https://doi.org/10.3390/ma12121982 - 20 Jun 2019
Cited by 4 | Viewed by 2690
Abstract
Typical artificial joints for humanoid robots use actual human body joints only as an inspiration. The load responses of these structures rarely match those of the corresponding joints, which is important when applying the robots in environments tailored to humans. In this study, [...] Read more.
Typical artificial joints for humanoid robots use actual human body joints only as an inspiration. The load responses of these structures rarely match those of the corresponding joints, which is important when applying the robots in environments tailored to humans. In this study, we proposed a novel, automated method for designing substitutes for a human intervertebral joint. The substitutes were considered as two platforms, connected by a set of flexible links. Their structural and material parameters were obtained through optimization with a structured Genetic Algorithm, based on the reference angular stiffnesses. The proposed approach was tested in three numerical scenarios. In the first test, a mechanism with angular stiffnesses corresponded to the actual L4–L5 intervertebral joint. Scenarios 2 and 3 featured mechanisms with geometry and structure comparable to the joint, but with custom stiffness profiles. The obtained results proved the effectiveness of the proposed method. It could be employed in the design of artificial joints for humanoid robots and orthotic structures for the human spine. As the approach is general, it could also be extended to different body joints. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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15 pages, 6421 KiB  
Article
Improving the Dimensional Stability and Mechanical Properties of AISI 316L + B Sinters by Si3N4 Addition
by Mateusz Skałoń, Ricardo Buzolin, Jan Kazior, Christof Sommitsch and Marek Hebda
Materials 2019, 12(11), 1798; https://doi.org/10.3390/ma12111798 - 03 Jun 2019
Cited by 5 | Viewed by 2943
Abstract
The following paper describes a new and effective method to obtain high-density sinters with simultaneously decreased distortions, produced by one press and sinter operation. This effect was achieved through the induced disappearance of the eutectic liquid phase. The study was carried out on [...] Read more.
The following paper describes a new and effective method to obtain high-density sinters with simultaneously decreased distortions, produced by one press and sinter operation. This effect was achieved through the induced disappearance of the eutectic liquid phase. The study was carried out on AISI 316L stainless steel powder that was mixed with elemental boron and silicon nitride. Boron was used as a sintering process activator. The scientific novelty of this publication consists of the use of a silicon nitride as a solid-state nitrogen carrier that was intended to change the borides’ morphology by binding boron. Based on the thermodynamic calculations, 20 blends of various compositions were tested for physical properties, porosity, microstructure, and mechanical properties. Moreover, phase compositions for selected samples were analyzed. It was shown that the addition of silicon nitride as a nitrogen carrier decreases the boron-based eutectic phase volume and both increases the mechanical properties and decreases after-sintering distortions. An explanation of the observed phenomena was also proposed. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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23 pages, 4113 KiB  
Article
Design of Reinforcement in Nano- and Microcomposites
by Małgorzata Chwał and Aleksander Muc
Materials 2019, 12(9), 1474; https://doi.org/10.3390/ma12091474 - 07 May 2019
Cited by 15 | Viewed by 2639
Abstract
The application of numerical homogenization and optimization in the design of micro- and nanocomposite reinforcement is presented. The influence of boundary conditions, form of a representative volume element, shape and distribution of reinforcement are distinguished as having the crucial influence on a design [...] Read more.
The application of numerical homogenization and optimization in the design of micro- and nanocomposite reinforcement is presented. The influence of boundary conditions, form of a representative volume element, shape and distribution of reinforcement are distinguished as having the crucial influence on a design of the reinforcement. The paper also shows that, in the optimization problems, the distributions of any design variables can be expressed by n-dimensional curves. It applies not only to the tasks of optimizing the shape of the edge of the structure or its mid-surface but also dimensional optimization or topology/material optimization. It is shown that the design of reinforcement may be conducted in different ways and 2D approaches may be expanding to 3D cases. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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20 pages, 6338 KiB  
Article
GHOST—Gate to Hybrid Optimization of Structural Topologies
by Bogdan Bochenek and Katarzyna Tajs-Zielińska
Materials 2019, 12(7), 1152; https://doi.org/10.3390/ma12071152 - 09 Apr 2019
Cited by 2 | Viewed by 2522
Abstract
Although well-recognized in the fields of structural and material design and widely present in engineering literature, topology optimization still arouses a high interest within research communities. Moreover, it is observed that the development of innovative, efficient and versatile methods is one of the [...] Read more.
Although well-recognized in the fields of structural and material design and widely present in engineering literature, topology optimization still arouses a high interest within research communities. Moreover, it is observed that the development of innovative, efficient and versatile methods is one of the most important issues stimulating progress within the topology optimization area. Following this activity, in the present study, a concept of a hybrid algorithm developed in order to generate optimal structural topologies of minimal compliance is presented. The hybrid algorithm is built based on two existing approaches. The first one makes use of the formal optimality criterion, whereas the second one utilizes a special heuristic rule of design variables updating. The main idea that stands behind the concept of the present proposal is to take the advantage of both algorithms capabilities. In a numerical implementation of the hybrid algorithm, the design variables are updated at each iteration step using both approaches, and the solution with a lower objective function value is selected for the next iteration. The numerical tests of the generation of minimal compliance structures have been performed for chosen structures including a real engineering one. It has been confirmed that the proposed hybrid technique based on switching between the considered rules allows the final structures having lower values of compliance as compared with the results of an application of basic algorithms running separately to be obtained. Moreover, based on promising results of the tests performed, one can consider the proposed concept of a hybrid algorithm as an alternative for other existing topology generators. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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20 pages, 7000 KiB  
Article
Shrinkage Optimization in Talc- and Glass-Fiber-Reinforced Polypropylene Composites
by Youngjae Ryu, Joo Seong Sohn, Byung Chul Kweon and Sung Woon Cha
Materials 2019, 12(5), 764; https://doi.org/10.3390/ma12050764 - 06 Mar 2019
Cited by 21 | Viewed by 5329
Abstract
The shrinkage of reinforced polymer composites in injection molding varies, depending on the properties of the reinforcing agent. Therefore, the study of optimal reinforcement conditions, to minimize shrinkage when talc and glass fibers (GF) (which are commonly used as reinforcements) are incorporated into [...] Read more.
The shrinkage of reinforced polymer composites in injection molding varies, depending on the properties of the reinforcing agent. Therefore, the study of optimal reinforcement conditions, to minimize shrinkage when talc and glass fibers (GF) (which are commonly used as reinforcements) are incorporated into polypropylene (PP), is required. In this study, we investigated the effect of reinforcement factors, such as reinforcement type, reinforcement content, and reinforcement particle size, on the shrinkage, and optimized these factors to minimize the shrinkage of the PP composites. We measured the shrinkage of injection-molded samples, and, based on the measured values, the optimal conditions were obtained through analysis of variance (ANOVA), the Taguchi method, and regression analysis. It was found that reinforcement type had the largest influence on shrinkage among the three factors, followed by reinforcement content. In contrast, the reinforcement size was not significant, compared to the other two factors. If the reinforcement size was set as an uncontrollable factor, the optimum condition for minimizing directional shrinkage was the incorporation of 20 wt % GF and that for differential shrinkage was the incorporation of 20 wt % talc. In addition, a shrinkage prediction method was proposed, in which two reinforcing agents were incorporated into PP, for the optimization of various dependent variables. The results of this study are expected to provide answers about which reinforcement agent should be selected and incorporated to minimize the shrinkage of PP composites. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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Review

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30 pages, 4933 KiB  
Review
Optimal Design of Plated/Shell Structures under Flutter Constraints—A Literature Review
by Aleksander Muc, Justyna Flis and Marcin Augustyn
Materials 2019, 12(24), 4215; https://doi.org/10.3390/ma12244215 - 15 Dec 2019
Cited by 22 | Viewed by 4725
Abstract
Aeroelastic optimization has become an indispensable component in the evaluation of divergence and flutter characteristics for plated/shell structures. The present paper intends to review the fundamental trends and dominant approaches in the optimal design of engineering constructions. A special attention is focused on [...] Read more.
Aeroelastic optimization has become an indispensable component in the evaluation of divergence and flutter characteristics for plated/shell structures. The present paper intends to review the fundamental trends and dominant approaches in the optimal design of engineering constructions. A special attention is focused on the formulation of objective functions/functional and the definition of physical (material) variables, particularly in view of composite materials understood in the broader sense as not only multilayered laminates but also as sandwich structures, nanocomposites, functionally graded materials, and materials with piezoelectric actuators/sensors. Moreover, various original aspects of optimization problems of composite structures are demonstrated, discussed, and reviewed in depth. Full article
(This article belongs to the Special Issue Optimal Design of Materials and Structures)
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