Antonio A Fernandes

• Eng.Mec,MSc,PhD
• Professor Emeritus at University of Porto-Faculty of Engineering

Pelvic floor disorders (PFD), including Pelvic Organ Prolapse (POP), can negatively impact a woman’s daily activities and quality of life. POP is a growing concern, with an increasing number of cases each year and significant numbers of women going through surgery to alleviate it. Traditional interventions like the use of mesh implants have certain...

Pelvic organ prolapse (POP) is a common condition among women, characterized by the descent of pelvic organs through the vaginal canal. Although traditional synthetic meshes are widely utilized, they are associated with complications such as erosion, infection, and tissue rejection. This study explores the design and fabrication of biodegradable au...

Pelvic organ prolapse (POP) occurs due to inadequate support of female pelvic organs and is often treated with synthetic implants. However, complications like infections, mesh shrinkage, and tissue erosion can arise due to biomechanical incompatibilities with native tissue. This study aimed to optimize the melt electrowriting process using medical-...

Purpose Develop biodegradable meshes as a novel solution to address issues associated with using synthetic meshes for POP repair. Design/methodology/approach Computational models were created with variations in the pore geometry, pore size, filament thickness, and inclusion of filaments around specific mesh regions. Subsequently, one of the meshes...

The emergence of new rapid prototyping techniques such as melt electrowriting and their application in the development of medical devices, enables new geometries for surgical meshes that were previously limited by current conventional manufacturing methods. The change in geometry allows a direct impact on the mechanical behavior of surgical meshes...

Digital Human Modeling and Medicine: The Digital Twin explores the body of knowledge and state-of-the-art in Digital Human Modeling (DHM) and its applications in medicine. DHM is the science of representing humans with their physical properties, characteristics and behaviors in computerized, virtual models. These models can be used standalone or in...

The conceptual activity of developing a product is the most important phase of the system design process, since it is through it that it is possible to materialize the satisfaction of a need or to solve a problem (Blanchard and Fabrycky in Systems Engineering and Analysis. Prentice Hall, 2006; Cross 2001a; Pahl and Beitz in Engineering Design. A sy...

Product development models provide a roadmap to transform an idea into a concept and a viable product.

A project is a temporary undertaking to create a product, a service or more generally an outcome (PMBOK in A Guide to the Project Management Body of Knowledge, Project Management Institute, Newton Square, PA, 2013). The temporary nature of a project means, that its duration is limited in time, regardless of whether the outcome is positive or negati...

The context in which companies have to operate today is highly dynamic and uncertain. On the other hand, many products have a high degree of complexity. These two aspects, uncertainty and complexity, require a paradigm shift in the way companies design their organizational structure and innovation processes. One answer may lie in the streamlining o...

Since the early nineteenth century, the economies of countries have moved from a structure based predominantly on agricultural production to the production of products, and since the mid-twentieth century to economies in which services have an increasing weight in the GDP (World Bank in World Development Indicators: Structure of output; Chesbrough...

Traditionally, innovation management is based on the analysis and identification of promising opportunities and the development of plans that allow their materialization: to achieve this goal it is necessary to identify the key strategic technologies and define a roadmap of their foreseeable evolution in the future (MacCormack 2006; Tennenhouse 200...

The globalization and widespread adoption of digital technologies, by creating a strongly competitive environment at a worldwide level, has called into question management models and formulas which, in the past, ensured the success of many companies and organizations. Globalization has, not only facilitated the access to new markets and information...

Additive manufacturing and 3D printing technologies enable personalised treatments using custom-made prosthetics, implants and other medical devices. This research aimed to characterise novel biodegradable polycaprolactone (PCL) implants for pelvic organ prolapse repair, produced using melt electrospinning technology. PCL mesh filaments were printe...

Pelvic organ prolapse (POP) is a pathology that affects many of the female population and interferes with everyday activities and patients' comfort. In many cases, it requires treatment and surgery. Currently, the diagnosis is generally made by observation, which creates subjectivity both in individual analyses and in evaluating the condition devel...

The epiretinal membrane is a thin sheet of fibrous tissue that can form over the macular area of the retina, and may result in the loss of visual acuity or metamorphopsia, due to superficial retinal folds. A vitrectomy surgery, the current treatment procedure for this pathology, is only performed after symptoms are present. However, sometimes the p...

Synthetic implants were used for repair of anterior compartment prolapses, which can be caused by direct trauma resulting in damaged pelvic structures. The mechanical properties of these implants may cause complications, namely erosion of the mesh through the vagina. In this study, we evaluated, by modeling, the behavior of implants, during Valsalv...

Over the past decade, melt electrospinning writing has attracted renewed attention. When combined with three-dimensional (3D) printing capabilities, complex 3D structures can be produced, from ultrafine fibers in the absence of toxic solvents, making it particularly attractive to fabricate customized scaffolds and implants for medical applications....

This work presents global and local fatigue approaches for snug-tight (common in rack structures) and preloaded bolted joints using thin hot-dip galvanized steel plates, where the zinc coating results in a low friction coefficient. Moreover, S-N data supporting the current revision of Eurocode 3 (EN 1993-1-9) is generated by considering remote and...

The female pelvic cavity involves muscles, ligaments, endopelvic fasciae and multiple organs where different pathologies may occur, namely the pelvic organ prolapse (POP). The synthetic implants are used for the reconstructive surgery of POP, but severe complications associated with their use have been reported, mainly related to their mechanical p...

This paper presents experimental research aimed at addressing the fatigue behaviour of thin-walled cold roll-formed steel sections, very commonly used in rack structures. This research is performed under the FASTCOLD-RFCS project, which aims to fill an existing gap on fatigue design rules. A new design S-N curve is derived from an innovative testin...

Although several old riveted bridges served more than 100-150 years in the world, some of them are still in the application, generally limited by the economic budget or cultural relic protection reason. Hence, the status of those bridges needed to be evaluated to support the bridge management and rehabilitation, especially with the increasing traff...

There are many old riveted highway and railway bridges, constructed 100-150 years ago in Europe and North America. In Portugal, it is counted that about 100 riveted bridges, which were built based on traffic intensity and vehicle weight, are no longer suitable nowadays. However, mainly due to economic reasons, those riveted bridges are still in ser...

Racking systems applied in logistics warehouses are built with thin steel sections that are joined by bolted connections. In fully automatic systems, these structures are loaded 7/7 days and 24/24 hours raising fatigue issues due to the cyclic nature of the resulting stresses. According to the current industrial practice, those bolted joints are ti...

In large companies, warehouse logistics usually include shuttle pallet carriers that are responsible for the transportation of various goods and products. These shuttles run along steel rails, which are usually produced from thin metal sheets that are cold roll-formed into the desired section. These shuttles also work 24 hours a day, 7 days a week,...

This paper presents results from an experiment using electroencephalography to measure neurophysiological activations of mechanical engineers and industrial designers when designing and problem-solving. In this study, we adopted and then extended the tasks described in a previous functional magnetic resonance imaging study reported in the literatur...

This paper presents results from an experiment using EEG to measure neurophysiological activations of mechanical engineers and industrial designers when designing and problem-solving. In this study, we adopted and then extended the tasks described in a previous fMRI study reported in the literature. The block experiment consists of a sequence of 3...

Limit: 350 words + References + Figures) In the last 10 years, domain-related EEG design studies (Nguyen & Zheng 2010; Liu et al. 2018; Liang et al. 2017), functional near-infrared spectroscopy (fNIRS) design studies (Shealy and Gero, 2019) and fMRI studies (Goucher-Lambert et al. 2019) of mechanical engineers, graphic designers (Elamil et al. 2011...

Nowadays, in the field of logistics engineering, rack structures prepared for automatic shuttles that are responsible for the intensive transportation and storage of various goods and products are used to deal with the logistics of a large warehouse. These shuttles are automated and can work non-stop in a 24/7 economy. In order to move through the...

Creativity is recognized as essential for changing the design space from constrained to open spaces. This study compares the neurophysiological activations of 18 professional industrial designers in two prototypical tasks, a problem-solving constrained layout task and an open design task. The analysis focused on measuring the cognitive demand in th...

We present results from an EEG experiment EEG to measure neurophysiological activation to study novice and experienced designers when designing and problem-solving. We adopted and extended the tasks described in a previous fMRI study. The block experiment consists of 3 tasks: problem-solving, basic design, and open layout design. The block is prece...

This paper presents results from an experiment to determine brain activation differences between problem-solving and designing of industrial designers. The study adopted and extended the tasks described in an fMRI study of design cognition and measured brain activation using electroencephalography (EEG). By taking advantage of EEG's high temporal r...

A histologically motivated (HM) coefficient that establishes a link between tissue's microstructure and material model through histological data is used in the prediction of the mechanical properties of vaginal tissue that is subjected to multiaxial loading conditions. Therefore, the material parameters were based on an HM coefficient obtained from...

This paper presents results from an experiment to determine brain activation differences between problem-solving and designing of mechanical engineers. The study is part of a research project whose goal is to correlate design cognition with brain behavior across design domains. The study adopted and extended the tasks described in a fMRI study of d...

Pelvic organ prolapse (POP) is a complex condition resulting from defects in the supporting structures of the vagina [1]. POP affects 25-41% of middle-aged and elderly women [1] and is estimated that from 2010 to 2050, the total number of women undergoing surgery for POP will increase by 48.2% [2], with a re-operation rate of 30% [3]. Until now, th...

New tools from neuroscience allow design researchers to explore design neurocognition. By taking the advantage of EEG's temporal resolution we give up spatial resolution to focus on the performance of time-related design tasks. This paper presents results from an experiment using EEG to measure brain activation to study mechanical engineers and arc...

Despite there being many studies that have evaluated breast implant rupture, there is no consensus about causes and incidence. Most studies lack a multifactorial analysis of what causes breast implants to rupture. To fill this gap, an experimental protocol was developed to compare ruptured and intact Poly Implant Prothèse (PIP) breast implants from...

Synthetic durable textile meshes used in pelvic organ prolapse (POP) may lead to graft related complications (GRCs). Mechanisms involved in the genesis of GRCs include implant biocompatibility, biomechanical properties and the host response. Electrospinning allows production of micro-sized fibres, which can physically mimic the natural extracellula...

This volume contains the proceedings of the XIX International Colloquium on Mechanical Fatigue of Metals, held at the Faculty of Engineering of the University of Porto, Portugal, 5-7 September 2018. This International Colloquium facilitated and encouraged the exchange of knowledge and experiences among the different communities involved in both bas...

Fatigue failures are a concern for old riveted steel bridges since most of them were not originally designed taking into account fatigue. The usual fatigue assessment approach for riveted joints consists of using the fatigue class 71 S-N curve proposed in Eurocode 3, part 1-9. However, this approach may lead to excessive conservative predictions si...

This paper presents a research about the monotonic and failure behaviours of bolted joints made of thin plates of S350GD and S355MC steels grades applied for rack structures. A full factorial matrix of static monotonic tests was performed considering two joints configurations, two material thicknesses, three surface coatings and two preload levels....

This paper presents a fatigue analysis of a type of fillet welded joint representative of one main joint of the steel box girder of the Alcácer do Sal railway bridge. From previous studies, it was found that the welded joint between the box girder diagonal and the central hanger gusset is one of the most stressed details of the bridge. This welded...

Racking systems, applied in logistics warehouses, are often built using zinc-coated thin steel plates that are joining by bolted connections. In fully automatic systems, these structures are loaded 7/7 days and 24/24 hours raising fatigue issues due to the cyclic nature of the resulting stresses. FASTCOLD project intends to provide fatigue design r...

Background: Pelvic organ prolapse, various types of incontinence (urinary incontinence, defecatory dysfunction), chronic cystourethritis, and sexual dysfunctions remain between the most common disorders in urogynecology. Currently, it is believed that the nature and number of births plays a major role in their development. Moreover, after these eve...

Mechanical characterization of living tissues and computer-based simulations related to medical issues, has become increasingly important to improve diagnostic processes and treatments evaluation. This work proposes a link between the mechanical testing and the material model predictions through histological data of vaginal tissue. Histological dat...

The maintenance and safety of ancient bridges is a major concern of governmental authorities. In particular, the safety of old riveted bridges fabricated and placed into service at the end of the 19th century deserves particular attention. These structures are susceptible to exhibit high fatigue damage levels due to their long operational period wi...

Pipelines can be submitted to extreme loading scenarios, which can engender structural instability in the form of large deformations and fracture by both monotonic plastic deformations of cyclic loads. Both monotonic ductile and low-cycle fatigue (LCF) damage mechanisms can occur for X52, X60 and X65 piping steel grades. The evaluation and predicti...

Cold roll forming is a continuous process aiming for progressive bending of sheet metal using stations with rotating rolls without changing material thickness; • The racking systems installed in warehouses are almost exclusively made of thin-walled cold-formed sections; • Fatigue design rules for cold formed steel sections are missing on a European...

This work consisted in conducting static/monotonic, slip/monotonic and fatigue tests in double-covered bolted butt joints with "snuggle tight" bolts. The data analyzed will be used in a new fatigue design regulation of bolted connections for cold-formed structural steels. Cold-formed structural steel profiles are currently used in various industria...

In the context of fatigue evaluation of riveted railway bridges, cross-girder to main beam connections are frequently critical details. Secondary effects, such as out-of-plane bending and dynamic amplifications due to the proximity to loading paths which in the case of old bridges were not taken into account in the original design, may lead to seve...

This chapter presents results of a testing programme of large-scale cyclic tests carried out on pipeline components manufactured with X52, X60 and X65 steel grades. Those tests cover distinct loading scenarios and geometries and were performed until final failure.

This chapter presents results of a testing programme of large-scale monotonic tests carried out on pipeline components manufactured with X52, X70 and X80 steel grades.

This chapter presents the results of numerical simulations of monotonic large-scale tests described in Chap. 4, using constitutive models described in Chap. 6 and material properties identified with material (small-scale) test data obtained in Chap. 2.

This chapter presents results of small-scale cyclic tests performed with smooth and notched specimens made of various pipeline steels. Both LCF and ULCF behaviours will be investigated. The generated experimental data is used latter in plasticity/damage models calibration/validation which will be later used in finite element simulation of large-sca...

This chapter presents results of numerical simulations of cyclic large-scale tests described in Chap. 5, using various constitutive models including some described in Chap. 6 and material properties identified with material (small-scale) test data obtained in Chaps. 2 and 3.

This chapter presents an overview of existing design procedures for the assessment of pipeline components undergoing monotonic and cyclic (ULCF) plastic damage conditions and comments on their limitations and suggestions for their possible update are proposed. This chapter covers more practical oriented guidelines for a strain based design of pipel...

This chapter presents results of small-scale monotonic tests performed with smooth and notched specimens made of various pipeline steels, covering medium to high strength steels and isotropic and anisotropic materials. Tension/compression, torsion and bending loads are explored. The materials investigated cover the API X52, X60, X65, X70 and X80 st...

Developments of constitutive modelling for plastic monotonic and cyclic damage behaviours are covered in this chapter.

Investigation on fatigue behavior of metallic bridges has deserved a lot of attention in the last decades since metallic bridges are vulnerable to fatigue damage. This problem is not exclusive of old riveted metallic bridges but it is also relevant of modern steel or composite welded or bolted bridges. The Faculty of Engineering has been involved i...

This paper presents a work about the monotonic and failure behavior of bolted joints made of S350GD and S355 steels, which are applied in cold-formed profiles for rack structures. A full factorial test matrix was performed considering two joints configurations (1+1 bolts and 4+4 bolts double shear joints), 2 material thicknesses (2 and 3 mm), 3 coa...

A class of fatigue crack propagation models, based on elastic-plastic stress-strain histories at the crack tip region and smooth specimens strain-life relations, have been proposed. The UniGrow model is an example of such fatigue crack propagation model, which uses the residual stresses developed at the crack tip, to assess the actual fatigue crack...

Requirements of industrial piping and pipelines to withstand extreme cyclic loading conditions have been motivating increasing interest on a particular extreme fatigue regime: the ultra-low cycle fatigue (ULCF). This damage domain corresponds to a transition between low-cycle fatigue and monotonic ductile damage. Albeit better understanding of this...

Recent studies predict that by 2060, people aged 65 or more will account to one third of the European population. These statistics raise questions regarding the sustainability of the society, so technological solutions have been emerging to prolong the active age of European citizens. One of the main impairments for elders to have an active life is...

For decades, women have undergone breast implant surgery either for health or aesthetic reasons. Some adverse effects have made their history full of events, showing the complex factors involved in the interaction of the device with the human body. Understanding the adverse outcomes is a key factor to improve the breast implants. This will help to...

This book covers the development of innovative computational methodologies for the simulation of steel material fracture under both monotonic and ultra-low-cycle fatigue. The main aspects are summarized as follows: i) Database of small and full-scale testing data covering the X52, X60, X65, X70 and X80 piping steel grades. Monotonic and ULCF tests...

Pipelines and piping components when subjected to extreme loading conditions (e.g. earthquakes, hurricanes, support settlements, industrial plant shutdown) undergo large plastic deformations, associated with widespread yielding, leading to fracture, either due to monotonic loading or ultra-low-cycle fatigue (ULCF) or extreme low cycle fatigue. ULCF...

The use of prostheses for hernia surgery, made from synthetic polymers may lead to development of postoperative complications. The reason for this can be the mismatch of the mechanical properties of meshes and the loads acting on them. The aim of this work was to investigate the behavior of 3 different hernia meshes under in vitro simulated physiol...

The vaginal wall and pelvic floor organs must adapt to pregnancy. This requires pelvic floor tissues to change their biomechanical properties. Nevertheless, epidemiological studies show that many women fail to recover completely from these events. The aim of this study was to investigate the effect of consecutive pregnancies on pelvic floor soft ti...

A probabilistic approach to non-linear damage accumulation for variable amplitude fatigue is developed in this work. A damage model proposed by Huffman & Beckman [1] is used, in which non-linear damage is modeled by calculating the damage of each cycle based on the state of damage when that cycle occurs, using the assumption that damage accumulatio...

Pelvic floor soft tissues undergo changes during the pregnancy. However, the degree and nature of this process is not completely characterized. This study investigates the effect of subsequent pregnancy on biomechanical and structural properties of ovine vagina. Vaginal wall from virgin, pregnant (in their third pregnancy) and parous (one year afte...

Breast implant durability and the mechanisms of rupture are important topics in the medical community, for patients, manufactures and regulatory medical agencies. After concerns about the Poly Implant Prosthesis (PIP) implants, the need for understanding the adverse outcomes and the failure mode to improve the breast implants increased. The objecti...

This paper proposes an experimental study aiming to evaluate stress intensity factors (SIFs) for fatigue cracks propagating under pure mode I and mixed-mode I+II for a S235 structural steel. Compact tension (CT) specimens with a side hole were manufactured in order to generate a stress field, ahead of the crack tip, resulting in mixed-mode fatigue...

The use of prostheses for hernia surgery, made from synthetic polymers, may lead to the development of postoperative complications. The reason for this can be the mismatch of the mechanical properties of meshes and the loads acting on them. The aim of this investigation was to explore the effect of in vitro degradation process and repetitive loadin...

Background There is societal concern regarding potential health problems associated with breast implants. Much of this distrust climate was a reaction to the Poly Implant Prosthesis (PIP) scandal. Studying the mechanisms of implant rupture is an important step for their improvement. The mechanical behaviour of breast implant shells was studied on e...

Fatigue crack growth models based on elastic-plastic stress-strain histories, at the crack tip vicinity, and strain-life damage models have been proposed. The UniGrow model is a particular case of fatigue crack propagation models. The residual stresses developed at the crack tip play a central role in these models, since they are used to assess the...

Background: The durability of breast implant material is associated with failure probability, increasing with time from implantation. The current study avoided the bias introduced by biological factors, to systematically investigate the degradation over time of shell materials. The same fundamental physical and chemical conditions were maintained...

This paper reviews the existing literature on the tests used to determine the mechanical properties of women breast tissues (fat, glandular and tumour tissue) as well as the different values of these properties. The knowledge of the mechanical properties of breast tissue is important for cancer detection, study and planning of surgical procedures s...

Fatigue damage under extreme cyclic plastic loading conditions (ultra-low-cycle fatigue (ULCF)) has been increasingly investigated motivated by several applications involving structures and mechanical components, such as pipelines, that may be, during operation, likely exposed to severe cyclic loading regimes (e.g. accidental loads, earthquakes, pi...

The use of lightweight materials in the automotive industry for structural parts has been increasing in recent years in order to reduce the overall vehicle's weight. New innovative lighter materials are being developed nowadays to accomplish that objective. In order to keep or even increase passenger's safety, structural parts made of these materia...

Ultra or extreme low-cycle fatigue of steels has been deserving increasing interest by the researchers since it corresponds to a fatigue domain not fully understood nor explored. It has been recognized that fatigue damage under extreme loading conditions is representative of several practical applications (e.g. seismic actions, accidental loads) an...

Human-centered design methodology applied to the development of health care products and in particular medical devices (MD) requires redoubled efforts and attention due to the complexity of the environment variables and the demanding condition of the end users. MD industries operate in a network of stakeholders in which clients are not the final us...

Since the successful introduction of synthetic tapes for the treatment of stress incontinence, synthetic meshes have been used increasingly to perform surgical repair for pelvic organ prolapse (POP). One concern about the use of these synthetic grafts involves the likelihood of graft related complications (GRCs) [1]. One recent suggestion on mesh u...

The use of innovative lightweight materials for structural design in the automotive industry is no longer a novelty. When joining different parts made of these new materials it is clear that adhesives are one of the best solutions. However, the selection of a suitable adhesive for this application and the performance of the joint under real car con...

Seismic actions, soil settlements and landslides, fluctuations in permafrost layers, accidental loads, and reeling are responsible for large plastic deformations and widespread yielding of pipelines, which may lead to damage or failure, either due to monotonic loading or cyclic plastic strain fluctuations of high amplitude and short duration (e.g.,...

Cohesive zone elements used in finite element analysis are a reliable way to design and predict the behaviour of the joint. The characterisation of the traction separation law used in these models is done using tensile and fracture tests, and the parameters of such laws depend on humidity and temperature. Water diffusion tests are therefore necessa...

The availability of probabilistic fatigue strength S–N data for riveted connections is essential to carry out reliability analysis of ancient riveted bridges. This paper proposes a procedure to derive probabilistic S–N fields for riveted connections, using material fatigue data and detailed finite element modeling of the joints. Strain-life fatigue...

The present paper introduces the Framework of Awareness to the analysis of ergonomics in design. The framework derived from a doctoral research that took the Lean Thinking perspective by adopting the concept of MUDA and its set of principles as dimensions to study designers’ behavior. Results were integrated into a Framework of Awareness to critica...

This paper presents an investigation concerning the ultra-low-cycle fatigue (ULCF) characterization of large-scale elbows produced from line pipes subjected to hot bending process. Two distinct pipes were used in this process: a 16” (w.t. 9.5 mm) X60 and an 8 5/8” (w.t. 5.59 mm) X65 pipes that were bent to 45 and 90° elbows (8 tests). Cyclic extern...