Rui B. Ruben

Polytechnic Institute of Leiria | ESTG · Departamento de Engenharia Mecânica

Bone tissue engineering (BTE) is an important field of research, essential in order to heal bone defects or replace impaired tissues and organs. As one of the most used additive manufacturing processes, 3D printing can produce biostructures in the field of tissue engineering for bones, orthopaedic tissues, and organs. Scaffold manufacturing techniq...

The Effective Modulus Method ( EMM ), which simulates the effects of local and distortional post‐buckling to establish simplified design methodologies concept, is applied to the determination of the beam strength. This methodology was presented before [1], where the authors tested the results in columns, in comparison with experimental tests. In th...

One of the four throwing events in track and field is the javelin throw, and its objective is to throw furthest as possible. Most of the literature has focused on correlating the results with the biomechanical parameters, but no study was found comparing high-level female athletes with male athletes. In this study, we aimed a javelin throw kinemati...

Tracheal stenosis leads to breath and eating difficulties. Stents are a common procedure in patients with stenosis. Silicone stents have some performance limitations related with stent migration, development of granulation tissue and accumulation of secretions. Since tracheal tree is different from patient to patient is essential to develop a custo...

The design of thin‐walled steel members, subjected to compressive stresses, requires complex analysis to account the interaction between local, distortional and global instabilities. There are simplified methodologies that allow simulating the effects of local and distortional post‐buckling behavior in usual structural members. The Effective Width...

Pseudoexfoliation, one of the most frequent crystalline lens complex disorders, is prevalent in up to 30% of individuals older than 60 years old. This disease can lead to severe conditions, such as subluxation or dislocation of the lens, due to the weakening of the zonules. The goal for the present study was to understand the relevant biomechanical...

This study aimed to determine the temporal parameters in the rotational shot-put phases and the shot-put release conditions in elite athletes. To analyze your correlation with the result and to analyze the differences between the male and female athletes. Eight elite ath-letes were analyzed. The 3D kinematic analysis was applied, through two high-s...

Bone Tissue Engineering has been focusing on improving the current methods for bone repair, being the use of scaffolds presented as an upgrade to traditional surgery techniques. Scaffolds are artificially porous matrices, meant to promote cell seeding and proliferation, being these properties influenced by the permeability of the structure. This wo...

Computed tomography (CT) and X-ray images have been extensively used as a valuable diagnostic tool in dentistry for surgical planning and treatment. Nowadays, dental cone beam CT has been extensively used in dental clinics. Therefore, it is possible to employ three-dimensional (3D) data from the CT to reconstruct a two-dimensional (2D) panoramic de...

This book contains the abstracts of all the keynotes and commnunications presented at the First International Conference on the Progress in Digital and Physical Manufacturing, held in the School of Technology and Management, from the 2nd to 4th October' 2019.

Additive manufacturing (AM) applied to the orthopaedic and surgical domains provided access to newer solutions for customised implants, customised scaffolds or even organ printing. These solutions are based on imagological data, gathered from CT-scans and/or MRI-scans. The compromise between patient’s radiation exposition and resolution along the f...

This work is intended to characterize the mechanical behavior of hybrid carbon–glass composite plates under combined loading of bending and torsion, and to determine the optimal ply fiber orientations to minimize the maximum out-of-plane displacement under such loading conditions. Hybrid composite plates were manufactured with 10 plies each and dif...

The combination of computational methods with 3D printing allows for the control of scaffolds microstructure. Lately, triply periodic minimal surfaces (TPMS) have been used to design porosity-controlled scaffolds for bone tissue engineering (TE). The goal of this work was to assess the mechanical properties of TPMS Gyroid structures with two porosi...

Mesh quality is essential to have a good and faster plastics injection computational analysis as well as reliable results. Additionally, a hexahedral mesh presents several numerical advantages over tetrahe-dral ones. However, hexahedral mesh generation is a complex and time demanding issue in finite volume method, so normally commercial software do...

The automated extraction of anatomical reference landmarks in the femoral volume may improve speed, precision and accuracy of surgical procedures, such as total hip arthroplasty. These landmarks are often hard to achieve, even via surgical incision. In addition, it provides a presurgical guidance for prosthesis sizing and placement. This study pres...

There are several commercial software for medical image dataset segmentation. However, most of them are expensive and not user-friendly. With our proposal of a new opensource software with a simple and specific graphical user interface (GUI), it is easy to segment a foetus from a 3D ultrasound medical image dataset. The segmented portion of images...

Femur segmentation can be an important tool in orthopedic surgical planning. However, in order to overcome the need of an experienced user with extensive knowledge on the techniques, segmentation should be fully automatic. In this paper a new fully automatic femur segmentation method for CT images is presented. This method is also able to define au...

Hot Runners mesh quality is essential for a good and faster plastics injection computational analysis. Addi-tionally, a hexahedral mesh presents several numerical advantages over tetrahedral ones. However, mesh generation of hexahedral meshes is a very complex and time demanding issue in finite element analysis, so normally commercial software do n...

Tissue engineering represents a new field aiming at developing biological substitutes to restore, maintain, or improve tissue functions. In this approach, scaffolds provide a temporary mechanical and vascular support for tissue regeneration while tissue in-growth is being formed. The design of optimized scaffolds for tissue engineering is a key top...

Computed Tomography (CT) is, in several cases, important in dental diagnosis. In fact, the panoramic reconstruction is commonly used in order to have a longitudinal view of the dental arch. Nowadays, dental CT equipments emit lower-dose radiation compared with other CT machines. Thus, dental CT became popular. However, there are some equipments tha...

Mandibular symphysis plates, used to heal fractures, can be made from different materials, normally titanium or CoCr alloys. In this work these two materials are tested and compared in order to study the plate's performance in fracture stabilization. This is a computational work performed with the advice of Brazilian maxoillofacial surgeons.

RESUMO: O objetivo deste estudo consistiu na análise cinemática da técnica de salto em altura, onde se pretendeu obter o padrão da técnica Fosbury Flop. Este tipo de análise é importante para estudar e otimizar a performance dos atletas. A amostra selecionada baseou-se em quatro atletas, que participam regularmente nas competições nacionais. Para e...

Aseptic loosening is the main cause of total hip arthroplasty failure. For cementless hip stems loosening is strongly related with a poor primary stability, and also with an excessive bone tissue loss. For cemented prostheses it is also possible to identify biological and mechanical reasons, such as bone remodelling, cement fatigue, cement-bone and...

The success of a total hip arthroplasty is strongly related to the initial stability of the femoral component and to the stress shielding effect. In fact, for cementless stems, initial stability is essential to promote bone ingrowth into the stem coating. An inefficient primary stability is also a cause of thigh pain. In addition, the bone adaptati...

IntroductionOptimization Methods for Implant DesignDesign Requirements for a Cementless Hip StemMulticriteria Formulation for Hip Stem DesignComputational ModelOptimal Geometries AnalysisLong-Term Performance of Optimized ImplantsConcluding RemarksReferences

The work presented in this paper was developed with the objective of increasing road safety for motorcycle drivers. Guardrails are traffic barriers placed along the roadsides to protect vehicles from hazards behind the barriers. These guardrails are constructed using standard steel W-beam mounted on spaced posts. When accidents involving motorcycle...

A multicriteria optimization model is developed to obtain the optimal geometry of the femoral component of a hip prosthesis. The objective function minimizes both the relative tangential displacement and the contact normal stress. For cementless stems, these two factors are relevant for the prosthesis stability and therefore for the implant success...

A computational model to obtain optimized geometries for the femoral component of hip prosthesis is presented. Using structural optimization techniques, the objective is to determine the shape of uncemented stems that maximize initial stability and improve performance. To accomplish this, the optimization problem is formulated by the minimization o...

Just after a Total Hip Arthrosplasty, the fixation of the cementless stem mainly depends on mechanical factors. If a good initial mechanical stability is achieved, new bone growths into the stem porous coating, leading to a desirable long-term biologic fixation. On the other hand, an inefficient primary stability could be painful for the patient an...

The primary stem stability is an essential factor for success of cementless hip stems. A correct choice of the stem geometry can improve the stem stability and, consequently, increase the life time of a hip implant. In this work, it is proposed a computational model for shape optimization of cementless hip stems. The optimization problem is formula...

This work presents a development of a computational model for shape optimization of cementless hip stems. To improve the stability of the prosthesis, the optimization problem consists of the minimization of the relative displacements on bone/stem interface. The design variables are parameters that characterize the geometry of selected cross section...