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Thermal fatigue widely takes place in light water reactor (LWR) piping systems. It is an important aging mechanism of a nuclear reactor. Thermal transient effects occur at the startup and shutdown of a nuclear power plant. During the thermal transients, local and global cyclic stresses are induced in the piping systems. They are exacerbated by local geometric imperfections and environmental factors, which may lead to crack initiation. The elbows of such piping systems are subject to various combinations of loads (internal pressure, bending, and torsion, as well as thermal fluctuations) during their service life. As can be seen, high-stress concentrations are developed in these piping elements. Therefore, it is important to make a failure evaluation. In this paper, a 12” pipe system segment, which was made with SA 106 Gr C steel, has been considered. It was composed by two straight sections joined by a long radius elbow. Typical start-up and shutdown transient effects of a BWR-5 were considered. A computer-aided thermo-mechanical analysis was carried out using the finite element method. The linearization of the stresses was considered, based on the ASME B & PVC Code Section III, subsection NB. Under these conditions, environmental fatigue was analyzed after 40-and 60-years operation.

Boiling water reactors have internal components manufactured with stainless-steel type 304. Some relevant cracks have been detected through the periodic inspections of their internal components. Re...

As a result of the pandemic, cases requiring endotracheal intubation have increased to support breathing through mechanical ventilation; this procedure is necessary when a patient cannot breathe on their own due to respiratory failure. For it, the laryngoscope is used. Even when using a laryngoscope, it is possible to injure the patient due to poor visibility at intubation. As a solution, some video-laryngoscopes present many advantages, such as reducing injuries, lowering the number of attempts to secure the airway and the image’s quality, and easy recognition of laryngeal structures. However, this type of device is not accessible to many health institutions due to the price. Therefore, this study proposes the design of a video-laryngoscope in the Computer-Aided-Design (CAD) software and constructed by additive manufacturing. For this design, the identification of the needs of the medical personnel in the anesthesiology and emergency medicine departments from the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (INCMNSZ) was taken into account. The design specifications provided by the users were used to create a proposal solution at the conceptual design level. The material and camera for the prototype instrumentation are presented with the model’s geometric parameters. Subsequently, virtual modeling of the device was carried out, and rapid prototypes were built to validate the performance of the design proposal. The final device was constructed by Selective Laser Sintering (SLS) using Nylon 12 as a construction material. Finally, the device was evaluated using airway simulators with the support of medical specialists to determine its functionality.

Flow-induced vibrations occur in some of the internal components of a nuclear reactor. When specific conditions are present, these vibrations may result in excessive deformations or fatigue that can generate mechanical damage. Several boiling water reactor (BWR) of nuclear power plants (NPP) have experienced failures in the jet pump assembly due to flow-induced vibration (FIV) which could be caused by acoustic pulsations derived from recirculation pumps, vibration induced by turbulence and vibration induced by leakage at the slip joint. The purpose of this paper is to establish a viable numerical methodology to evaluate the fluid-structural interaction at the slip joint of a jet pump. In this analysis, the fluid-structural interaction was evaluated with the finite element method and finite volume method with ANSYS® code in the case of two steel plates with a divergent gap. Results show that a critical velocity could cause fluidelastic instability, if only one flow in a two-way fluid-structural interaction was considered. This is one of the phenomena that could take place at the slip joint of a jet pump assembly.

Tumors, trauma and infections are the main reasons for subjecting a patient to a bone reconstruction made with the use of bone grafts or prosthetic elements, using for example components such as osteosynthesis plates, meshes and screws for their stabilization.This study focuses on the photoelastic analysis of a customized prosthesis of the jaw for a patient diagnosed with osteonecrosis. A resin model was manufactured as follows: DICOM files were processed in ScanIP software to obtain an STL file that was used to generate an antagonist model of the healthy section of the jaw using CATIA software, then, models were printed in Acrylonitrile Butadiene Styrene (ABS). Following the resin casting technique, the printed model of the jaw was used to construct a resin model, which is tested to determine its mechanical behavior.After carrying out the photoelastic analysis, it was found that the assembly process generates stress concentration zones. Here, the stress reaches a maximum value after the application of a bite force of 130.9 N in the premolars. In this study near the premolars, 3 stress concentration zones were identified and overlap of stress fields is reveled.The results show the importance of planning in the design and assembly process to obtain the best results in the reconstruction, reducing in this way the risk of a surgical reoperation due to problems of rupture or loosening of the prosthesis.

En el desarrollo de este trabajo se aplican las bases de la biomecánica del hombro para el análisis de su cinemática, describiendo sus grados de libertad y su movimiento, así mismo se realizó un modelo matemático, considerando al brazo como una cadena cinemática abierta. La caracterización del movimiento del brazo se realizó mediante videogrametría, con ayuda de un programa desarrollado en Matlab . La medición de los movimientos se realizó a dos personas sanas sin lesiones, utilizando marcadores colocados en puntos estratégicos, los movimientos medidos fueron de abducción-aducción y flexión-extensión, una vez tomado el video se analizó en el programa para registrar los resultados cinemáticos. Estos últimos fueron medidos en grados contra tiempo, y observando la diferencia de movimientos entre ambas personas.

This paper shows the methodology used for the evaluation of the structural integrity of a boiling water reactor (BWR-5). This evaluation is relevant, because this vessel is the coolant pressure boundary for cooling the nuclear core. In the case of this paper, an axial crack is postulated in the adjacent internal wall of a vessel to the core, which is denominated beltline. Such a crack is subjected to an internal pressure and neutron irradiation. Additionally, a crack on the inlet nozzle of the low-pressure coolant injection (LPCI) was also considered. The analysis presented in this paper, evaluated the transient conditions which take place during the start-up and shutdown of a BWR 5. The neutronic irradiation damage at the beltline was also incorporated to the analysis. It induces an embrittlement. Linear elastic fracture mechanics was applied with the requirements established at the Appendix G of ASME Code Section XI. The finite element method was used to simulate the transient conditions of the components considering the critical parameter, such as the service temperature, thickness, stresses and the material properties.

Today, assisted design software offers more capacity and iterations, and its methodology optimally solves geometries with enough rigidity and weight, keeping their specific characteristics desirable for some design objectives, and thus achieving originality, affordable functionality and reproducibility through manufacturing systems such as three-dimensional manufacturing. For this reason, the present study uses a computerized generative design method to optimize the main components of a cranial distraction system aiming to perform a geometric optimization of the original components and preserving the actual mechanical performance in spite of reducing the weight of the distractor components. By the use of commercial software packages such as PTC Creo Parametric©, PTC Creo Simulate©, Frustum©, Autodesk fusion 360°©, and Solid edge©, several generative proposals were evaluated. These evaluations were performed under load and boundary in order to preserve the cranial distractor function and optimize the amount of material used by the additive manufacture technique.

This work proposes and demonstrates the application of Biomechanics to make printed designs in 3D systems, in order to improve customized prosthetic components. The study provides solutions that benefit patients with orthopedic area defects. In addition, the publication of this work will increase the scientific production and international recognition of the National Polytechnic Institute.

A numerical evaluation of an orthognathic prosthesis used in patients with facial asymmetry and mandibular prognathism was performed for this study. Mechanical testing was also performed by using axial tomography (computed tomography scan), and experimental methods such as photo-stress and image correlation were included. Our clinical case was a patient diagnosed with prominent mandible and abnormal size; atypical morphology, abnormal mastication and sense of smell, and difficulty talking as a consequence of the bone deformity; bad alignment of the mandible and upper maxilla, atypical movement of the tongue and deficiency for the occlusion process (closing of the mouth). This study aimed mainly to characterize the mechanical stress and structural behavior of numerical models obtained by the patient’s clinical and morphological profile through a computational approach based on the finite element method.

Equinovarus foot or known as clubfoot is a frequent musculoskeletal deformity occurring at birth. It comprises a misalignment of the foot and shortened tendons and produces pain and serious physical limitations. It occurs mainly in patients with cerebral palsy, duchenne muscular dystrophy, residual clubfoot deformity, and spina bifida. The initial gold standard treatment for an equinovarus foot is the structural correction with the use of ortheses aimed to allow the patient to walk and perform rehabilitation exercises. These ortheses come mainly in the form of boots molded with plaster of Paris or fiberglass bandages. Premanufactured ortheses are also available and yield great resistance and support to the foot; however, they can be very costly and out of reach for some population. Recently, our research center of investigation and biomechanics laboratory (CILAB), with the assistance of the Instituto Politecnico Nacional (IPN) started printing three-dimensional personalized ortheses for diverse musculoskeletal problems, including clubfoot patients aiming to lower the costs of treatment for our pediatric patients. Our preset study analyzed the resistance of two 3D printed ortheses: one for a normal subject and another for a clubfoot patient through optical interferometry and numerical analysis. Our purpose was to anticipate failure of our personalized designs, especially in cases, where the foot gait is abnormal such as in the case of clubfoot patients.

The recirculation system of a BWR-5 has 20 jet pumps. They are submerged in water in the cylindrical annular zone of the reactor. Their main function is the development of a forcing flow through the nuclear core. It increases the power of the reactor compared with the one obtained by natural circulation. These components have an important safety function in the operation of the reactor. In accordance with document BWRVIP-41 R4, it was concluded that the vibration induced by cross flow over the jet pump assemblies is one of the degradation mechanisms of such pumps. In this paper, the vibration induced by the cross flow at a jet pump assembly BWR-5 was analyzed. A numerical approach was developed. The natural frequencies were obtained, considering the Fluid-Structure Interaction (FSI). The first natural frequency was 25.7 Hz. A Computational Fluid Dynamics (CFD) analysis was carried, in conjunction with the Power Spectral Density (PSD). A frequency of vortex generation of 0.48 Hz was obtained. A vortex generation analysis was carried out with the Q-criteria. The results showed that resonance conditions are unlikely. Therefore, the structural integrity of the jet pump assemblies is maintained.

The present study comprises a comparative exercise to determine stress, strain, and amorphic structural state in a hip prosthesis with the use of the photoelastic and image correlation technique. Several photoelastic models, some of them with a stochastic finish were created by the use of a computed tomography scan, stereolithographic three-dimensional printing, and rapid prototyping. Ideally, our results could yield a significant time reduction of techniques aimed to evaluate stress and strain of surgical models either pre or postoperatively.

Scoliosis and lordosis are medical conditions, which present an atypical curvature of the spine. These deformations can be easily diagnosed, altogether with the degree of their severity through orthopedic measurement processes and clinical reviews. However, the preformed studies which classify the severity of these deformations are, in their majority, empirical and present great opportunity for improvement. Therefore, they are based on radiographies that offer a clear image of the spine, but present the problem of a constant patient’s exposition to ionizing radiation and as a consequence an increment of potential hazards for health. This also means, results are subject to the physician’s interpretation and expertise. The present work intends to describe and analyze the design and function of a mechanical system that is capable of significantly reducing the radiological exposure of patients with scoliosis and lordosis. The main goal of this device is to diagnose both deformations by obtaining the angles of curvature of the patient’s spine, using a method that does not depend entirely on human interpretation.

This work details the study of the effectiveness in the use of plates, as a treatment support during the fracture of a mandibular angle. It also analyzes the mechanical operation of the fissure repair plates on the jawbone using methods like finite element simulation and image correlation experimentation. With the purpose to evaluate the mechanical capacities of a new prototype plate compared to one of the commonly used namesakes, since the mechanical capacities of the new model are unknown.

Human bone tumors, severe trauma, and infection are the main causes of large bone defects. Currently, these defects are repaired using reconstruction plates that connect remaining bone, without any bone grafting. This study focuses on two aspects: the first, experimental testings using digital image correlation and secondly numerical testing studies in order to evaluate the influencing factors in the design of a custom prosthesis and maxillofacial applications. In this work, it is proposed to design and characterize a prototype mandibular prosthesis for hemimandibulectomy recovery class IVc to a patient with bone cancer. For the design and prototype, the physical and morphological characteristics of the patient as well as the strength properties of the used material are necessary. The mandibular prosthesis prototype design will be created based on the 3D reconstruction of the mandible of tomographic studies, which were obtained using the ScanIP software. Subsequently, the 3D models were exported to a CAD software in order to fix the necessary adaptations to the bone. The 3D models were printed in acrylonitrile butadiene styrene, and a digital image correlation was used in order to evaluate the residual stress and strain differences which can be observed in all the cases, also in the case of implants and the remaining healthy bone, caused by masticatory forces.

In the present work, the effect of trauma impacts on the cranium and the influence of cranial brain fluid on the walls of the cranial vault are analyzed. Using experimental methods (photoelasticity and image correlation), as well as numerical methods with ANSYS Mechanical APDL®, the results were studied in order to know the mechanical behavior in the surface of the cranial vault in which the cranial plates for replacement or reconstructive surgery for injuries by trauma (third degree) are required. Also, it would be considered as an economic and capable option for prosthesis which only considers titanium and stainless steel as material for the replacement.

In this paper, a methodology has been proposed to obtain the response spectrum of a nuclear building caused by underground detonations. For the problem at hand, a reinforced concrete building containing a boiling water reactor was postulated. It was constructed on a hard soil with a zero-period acceleration of 0.26 g. Its structural damping was 7%. The building is subjected to horizontal vibrations originated from a detonation of 15 tons of TNT, located at a distance of 2000 m from the nuclear power plant site. Initially, an analytical evaluation was carried out to obtain the horizontal vibrations. In a second step, a foundation soil model was developed with the finite element method in conjunction with an explicit approach. ANSYS® Autodyn® code was used. The response spectrum due to the underground detonation was developed with the data obtained. It was compared with the safe shutdown earthquake (SSE) response spectrum and the operating basis earthquake (OBE) response spectrum. The results show that the seismic response spectrums envelop the explosion response spectrum. A resonance did not develop. The horizontal velocity is below the limits established by the regulations considered in this paper. Under this condition, the postulated building is safe.

The fatigue analyses are usually carried out with experimental data obtained in dry conditions. Nevertheless, a wet environment significantly affects the fatigue life of the elements exposed to these conditions. In this paper, the structural integrity of a feedwater piping system of a boiling water reactor (BWR-5), under wet environment fatigue conditions during 40 and 60 years of operation, was evaluated. A structural analysis of the piping system, between the feedwater nozzle and the adjacent piping support to the reactor pressure vessel, was done. The transient conditions, which are developed during the start-up and shut down, were taken into account. The fatigue analysis was developed in accordance with the Section III of the corresponding ASME Code. The environmental factors, which are related with the contact between the water and the internal surfaces of the piping system, were considered as penalty parameters. The procedure explained in the NUREG 6909 was followed. The results showed that the environmental conditions increased the cumulative usage factor, in comparison with those calculated in dry conditions.

In this paper the problem of guiding a parabolic trough solar concentrator through a system based on a water displacement mechanism is addressed. The actuator mechanism consists of a set of four on/off electrovalves in ”H-bridge” configuration, a small water pump, a sun sensor and two containers half-filled with water, installed on the side ends of the concentrator. To guide and balance the concentrator, a sliding mode controller (SMC) to enable / disable the opening and closing of the valves that control the direction and flow of water between the two containers is proposed. The validity of the implementation of the proposed law of control applied to the actuator mechanism is verified with stability analysis and simulation results.

La importancia de las pruebas mecanicas en la investigacion de nuevos materiales capaces de ser utilizados como elementos de remplazo para la estructura maxilofacial son imprescindibles, y tienen el objetivo de garantizar su correcto funcionamiento estructural una vez implantados; es por ello por lo que el presente trabajo se enfoca en la obtencion de las propiedades mecanicas en flexion y compresion de un nuevo material compuesto a base de resina isoftalica, hueso, hidroxiapatita y acero inoxidable; informacion que es usada en un ensamble virtual y estatico, cuyos componentes son: la protesis de rama y condilo, la estructura osea mandibular restante y los elementos de sujecion (tornillos). En dicho ensamble se contemplan de manera independiente las propiedades mecanicas de los materiales de cada uno de los elementos que lo conforman, con la finalidad de obtener datos reales y relevantes de su comportamiento, y de esta forma determinar desde el punto de vista mecanico, si puede ser usado en la manufactura de protesis maxilofaciales.

In this paper, the Cumulative Usage Factor (CUF) of a High Pressure Core Cooling System (HPCS) reactor nozzle of a Boiling Water Reactor was calculated. This fatigue damage has been caused by the sudden injection of cold water into the reactor vessel through such nozzle. For this purpose, a three-dimensional analysis was carried out. Accordingly, a transient heat transfer analysis was developed. The temperature distribution was determined. With this information, the stress analysis was carried out. The safe end was restricted to move along its axial direction and the forging end was free to expand axially and radially. The resultant stress field established the magnitude of the alternative stresses. In the last step, a fatigue analysis was developed. The most critical point is the junction of the nozzle with the thermal sleeve. The fatigue performance was evaluated during a period of sixty years. It was assumed that 1.5 cycles per year will take place. The fatigue curves of ASME code section III were used. The results showed that the Cumulative Usage Factor (CUF) vary with the temperature injection, being 0.4090 when the water injected was 4.44°C and 0.3797 when the water temperature was 37.77°C. Both of them were estimated for a period of 60 years of operation. Therefore, damage is reduced as the temperature of the injected water increases. Besides, it is advisable to at least follow the recommendations of the NUREG ́s 1800 and 1801 [1, 2]. In this way, the aging of the nozzle is adequately managed.

In this work, the design and numerical evaluation of a personalized hip prosthesis for a 31-year-old male patient, who suffered of unilateral coxarthrosis, was performed. Based on the information obtained of the patient’s computerized axial tomography and the employment of specialized design platforms such as Solidworks®, a numerical analysis was performed for the prosthetic model in conjunction with the anthropometric data of the patient following the finite element mathematical method. Furthermore, the natural posture of the patient was taken into consideration every time the patient balanced the total weight on one leg. Furthermore, the structural mechanical evaluation of the prostheses was set under evaluation, considering the osseous integration of the femoral bone and the acetabulum before and after surgery.

In the present work a proposal for the design of an auxiliary device for people who suffer from blindness or weak vision in form of a diadem, is developed. The device is capable of orientating patients in an urban environment. The main goal of this project is to assist patients when performing displacements and diminish the possible collisions with objects or obstacles at the height of their heads or at a middle height (abdomen height), so that patients can have more freedom when performing a certain movement or displacement. The auxiliary system emits vibrations with certain intensity, according to the distance between the object and the patient. The vibrations present the tendency to be stronger when the distance between the patient and the object is shorter and rather weak when the distance is longer. This mechanism avoids the usage of sounds or similar tools that normally confuse or disorientate the user.

Flexible flat foot in infants can cause pain and physical limitation. Surgical treatment is preferred when pain is severe. Evans enlargement of the lateral aspect of the calcaneus has good results but has complications due to the collapse of bone grafts. Tridimensional segmentation of anatomical areas allows to obtain stereolithographic models that can be numerically analyzed. A stereolithographic model of a healthy calcaneus was obtained from a CT and virtually sectioned to simulate Evans osteotomy. A wedge-shaped implant was made and implanted as described by Evans. Both models were analyzed with a finite element software, the calcaneus model comprised cortical and cancellous bone layers (E = 20 GPa and 457 MPa respectively) The wedge-shaped was assigned PMMA properties (E = 2.4GPa). Three phases of human gait were simulated and stress obtained. The highest von Mises stress occurred at the stance phase (18.25 MPa). None of the stress exceeded the yield stress for all materials in all phases. Reconstruction of anatomic models and implants using a stereolithographic technique allow to predict stress and failure. These models could also be printed 3D to elaborate novel implants.

In the present work, the creation of a tridimensional electronic prosthesis which intends to replace the left hand’s phalanges of a patient who suffered severe burns and needed to undergo a partial amputation surgery was performed. Parting of a CT tomography composed of 539 images, the contour delimitation, and separation of each phalanx was carried out through the usage of computerized platforms, such as 3D Slicer and Scan IP. Both software allow the user to analyze every single image in three different planes (axial, sagittal and coronal) and segment the areas of interest, in this case, the index, middle, ring and little fingers’ phalanges. Subsequently, with the support of the platform SolidWorks©, each phalanx was detailed for its connection and posterior 3D printing, implementing an electronic mechanism capable of reproducing flexion-extension movements. The computerized final model was also submitted to mechanical force tests and force simulations based on the analysis of finite elements to ascertain the selected material’s and model’s resistance.

The Nuclear Steam Supply System (NSSS) of a Boiling Water Reactor (BWR) has been designed for directing and controlling the steam flow, from the reactor pressure vessel to the turbine. Furthermore, this system provides over-pressure protection for the Reactor Coolant System (RCS) and prevents fuel damage by restricting the loss of coolant in the reactor. In this paper, the fatigue and aging of a generic Main Steam Isolation Valve (MSIV) was analyzed. The body of such valve was evaluated. These conditions affect adversely the capacity and the functions of the valve. In the case, there is the risk of uncontrolled releases of radioactive particles to the external environment. The thermal fatigue analysis, which is reported, included three main thermal transients. They affect the NSSS system during its operating life. They are test of valve, shutdown of plant and turbine stop valve closure (TSV). All these evaluations were developed with a 3D CAD model in conjunction with the Finite Element Method. Finally, the remaining life and the allowable fatigue cycles were determined before the failure takes place. This work was based on the guidelines applicable to Nuclear Power Plants (NPP´s) contained in the ASME code.

The design and development of highly accurate prostheses for individual cases according to the patient’s condition is one of the current challenges in the fields of medicine and engineering. The use of tomographic archives uploaded to a specialized computer program for its rendering (creation of a 3-D model) allows specialists decide on the surgical approach to take, by creating a model which possesses precise dimensions, corresponding to the exact anatomy of the patient. The use of computational programs (CAD/CAM programs) not only allows the development of better designs, but also the evaluation of the proposed models through a force moment analysis in conjunction with the assignment of the endorsed materials for its posterior development by setting the prototypes to the Maximum Shear Stress principle and analyzing the results of its displacement’s and the Stress von Mises’ tests, specialists have the opportunity to know if the final design will be able to support the muscular tensions and occlusion forces caused by the elongation of the muscular fibers.

Substitution for the loss of human members due to different natural consequences has been a reality for many thousands of years. Over time, the evolution of knowledge and technologies, just as the discovery of new materials, gave rise to inventions in the fields of robotics, in particular biomechanics, that have provided human beings with complementary limbs that are improved upon every day. Based on the advances of electronic components, more efficient systems are developed for patient monitoring, which allows for more accurate control and monitoring of the prosthesis, as well as the vital signs of the patient. With the help of technology, efficient treatments are applied or to recover bodily parts as far as possible. This paper presents the design for a prototype of a monitoring system for spinal prosthesis, which an system Arduino UNO®, an infrared sensor, an accelerometer and a micro SD memory are used. In addition, computational tools are used for the development of the algorithm, which allow the monitoring of the prosthesis. As a result, measurements are obtained in the Arduino® system for the behaviour and movement of the prosthesis such as the displacement of the vertebra and angular velocities, which are stored in a micro SD. The application of new technologies in spinal prostheses is also obtained in order to make a diagnosis less costly and available in real time.

In this paper, the stress analysis of the support structure (skirt) of a Boiling Water Reactor (BWR-5) vessel is presented. Three transient loading conditions, which take place during the life of the plant, were evaluated, in order to determine the structural integrity under fatigue loading. The concept of Cumulative Usage Fatigue (CUF) was used. The guidelines of the subsection NB and subsection NF of Section III of the ASME Code were taken into account in the evaluation in conjunction with the Finite Element Analyses (FEA). In addition, the environmental fatigue penalty factors (Fen) were also considered during the evaluation. The environmental conditions affected the integrity of the skirt. Besides, a perturbation in the stresses was observed due to the dynamic forces generated by the jet pumps, which increased the CUF in the skirt.

In the present work, the importance and consideration of the use of scaffold structures for biomaterials is highlighted in order to be applied in prosthetic cases where it is possible to consider a three dimensional porous structure, maintaining the mechanical properties that are necessary for the right functioning of the models under preoperative and postoperative loads. The requirements for biodegradable and bioactive properties of the models are indicated by surgical specialists, with the purpose of considering both the shape and type of the scaffold and its influence in the building of diverse mechanical supports. A specific maxillofacial application case of models, a mandibular implant, whose numerical-experimental properties and behaviors based on bone, polymers and metal alloy structures used in the manufacturing of models, were used to compare the variation of the scaffold structure types. Furthermore, models printed in 3D using an acrylonitrile butadiene styrene (ABS) polymer with different fiber orientations and type of scaffolds will be considered as an initial part of the case studies.

Nowadays, one billion people live with some form of disability, and face difficulties in the development of activities and integration into society. In future years, this problem will increase. The generation of devices for the rehabilitation of people who suffer some kind of disability is a task that has been studied and attacked for years. The exoskeleton (exo means “outside” in Greek) is an external skeleton that encloses the body of the arthropod as an armor, performing a mechanical function of structural support and protection. Conventional manufacturing processes, present advantages as well as disadvantages, within its disadvantages are the long times for its manufacture and construction, and high cost of manufacturing, since it is not a serial production. The guidelines and actions of the methodology for the manufacture of an exoskeleton of assistance for human gait with problems of acute transverse myelitis.

A study of the wear damage of a blade of the seventh-stage of the compressor of a gas turbine was carried out. The manufacturer recommends routine maintenance (30,000 h) to reduce the chances for the shutdown of the gas turbine. In this study, the C40 turbine was analyzed in the field at 24,000 h (shutdown) and out of service after 30,000 h. The turbine was operating in the city of Campeche, Mexico, in a very aggressive environment, where the entry of solid particles is unavoidable. The gas turbine combines high performance operation with rugged industrial construction. This design provides high efficiency, low maintenance and a long service life. For power generation, the components that are in direct contact with the air at different stages of operation are the compressor blades which are exposed to severe wear damage for the impact of particles, environmental contaminants such as salts, sands and sulphur. Due to this fact, the wear damage on the turbine blades was analysed. The work was developed in two steps. In the first one, an analysis of boroscope images of the surfaces of the blades was carried out in the site, and out of service the study with destructive and non-destructive tests, using tribological characterization were conducted to obtain the chemical composition of the turbine blades, which were in operation, by using energy dispersive X-ray analysis (EDS). Hardness tests were also conducted, using the material that was employed to manufacture the blades. Additionally, optical microscopy and scanning electron microscopy (SEM) were used to identify the wear mechanisms on the surfaces. This allowed obtaining a more complete failure analysis. The wear modes were severe pitting action, large craters similar to those observed in solid particle erosion when the samples are impacted at normal incidence, corrosion and a few irregular scratches similar to ploughing action in abrasive wear.

In this work, a temporomandibular joint prosthesis system is designed in order to be manufactured and implanted. A computer tomography study of a patient with bone cancer and temporomandibular ankylosis was used. The specific design also considered a local socket to replace the mandibular fossa. The manufacturing of the system used stainless steel (AISI-316L). Mechanical evaluation and numerical testing were done using ANSYS code and PTC CREO Parametric 3.0, while in the biomechanical reconstruction, SCAN IP software was used. The fixation of the prosthesis in the patient is an important requirement and the structural behavior is studied using the finite element method (FEM). In order to design and personalize the implants, quick prototyping printer systems (ABS and PLA) were used, while for the manufacturing process, stainless steel 316L was considered, in order to get low costs. As a result of this research, the chewing process of the patient will be performed.

Purpose To evaluate the strain fields and to calculate the modulus of elasticity and Poisson's ratio of trabecular bone of the 6 lumbar vertebrae of the porcine spine by a 2-dimensional digital image correlation (2D DIC). Methods This study was performed through a 2D DIC technique and the specimens were tested under compression. The resulting images were analyzed numerically by 2D DIC. Then, representative regions of interest were examined. The strain fields were determined and stress-strain curves were obtained. Results The full field measurement of the strain in the lumbar bone spine was evaluated and with this data, the Young's modulus and Poisson's ratio were determined. Conclusions This research highlights the potential applications of noninvasive acquisition techniques in biomechanical analysis. This is useful in the mechanical characterization of bony structures and in the design of prostheses.

The structural integrity of a BWR nuclear power plant can be compromised due to severe dynamic loads. Acoustic loads coming from a Safety Relief Valve branch can be adversely amplified if the steam flow is increased at the Main Steam Piping. This phenomenon has been reported previously in one BWR nuclear power plant. Its steam dryer was fractured and loose parts were generated due to high-cycle fatigue. This event has driven the United States Nuclear Regulatory Commission to issue specific regulations to evaluate acoustic loads which would be detrimental to the BWR steam dryer. In this paper, the acoustic loads were simulated when the steam flow is incremented from normal operation conditions to an Extended Power Uprate condition. It was analyzed, when the output power was incremented 14% and 28%. The initial conditions were determined with Computational Fluid Dynamics under steady state condition. This data was used in subsequent transient analysis. The model of Large Eddy Simulation was used and the acoustic simulation was performed with the Fowcs Williams and Hawkings Method. The Power Spectral Density was obtained with Fast Fourier Transform. The frequency peaks were found between 148 Hz and 155 Hz. These results are consistent with those obtained with the Helmholtz model and other results reported in the open literature. The results show that the peak pressure can be increased up to six times in resonance conditions, corresponding to a power uprate of 28%.

Electromyography (EMG) is usually done with wet electrodes. They are commonly made with Ag/AgCl (silver chloride). In this case, an interface with the skin is created with a gel. The problem with such electrodes is that the signal is affected by the way the electrodes are fixed over the skin and the use of gel. Besides, they irritate the skin and they are sensible to artifacts of movement and other interferences. In order to avoid these problems, dry electrodes with microneedles, which records the EMG signals, were manufactured. The microneedles pierced the stratum corneum of the skin. They improved the contact with the skin and avoided the interference caused by the dead cells. Besides, the application of a conductor gel and the preparation of the skin was not required. The mecroneedles were manufactured on a copper substratum with a laser beam. They were coated with gold, which is a biocompatible material. Although the size of the microneedles was very small, a good shape was obtained. The manufacturing process was carried out with a high precision and its repeatability was guaranteed. This manufacturing process is quick and cheap. The determination of the operation parameters of the dry electrodes was based on the contact impedance between the skin and the electrode. The performance of the proposed electrodes was compared with the performance of the commercial wet electrodes. The average impedance obtained were 6.5 and 9 kΩ for the wet and dry electrodes, respectively.

The structural integrity of a jet pump assembly of a boiling water reactor (BWR) under hydrodynamic loading was evaluated. This arrangement, which has a riser joined with a couple of jet pumps by the transition piece, is part of the reactor recirculation system. It is submerged in water under pressure. The main function is to induce forced flow through the core of the reactor. A dynamic structural analysis was carried out with the finite element method. The first ten modes of vibration and their natural frequencies were calculated. The first five natural frequencies are in the range between 25 Hz and 40 Hz. In this analysis, it was considered that the jet pump assembly is supported at the riser brace. The restrainer bracket keeps together the riser with the two jet pumps and there is free movement at the slip joints.

The failure of polyethylene inserts in the prostheses of diverse members is the main cause for total replacement of the articulation. In this study, the most influential conditions for the different types of failures for a total knee replacement (TKR) causing the main wear or rupture were analyzed. Mexico, little research has been done on total knee prostheses (Rodriguez in Int J Phys Sci 7(43): 5779–5786, 2012, [1]), this being one of the main problems of national health. In the previous publications a few studies were conducted concerning the gait cycle in Mexican patients were made. One of the cases involved the TKR Scorpio™ II Stryker™ (Rodriguez in Revista Colombiana de Biotecnologia XV(1): 28–41, 2013, [2]) where axial and shear stresses have been analyzed and the way this functions in the gait cycle considering this type of prosthesis (Rodriguez in Revista Colombiana de Biotecnologia XV(1): 28–41, 2013, [2]). Due to the scarce resources with which it had to operate, the design of the components of the machine had to be improvised or modified, which is quite useful in two different cases. In present case, a hybrid-machine was developed, adapting new mechanical components on the pin-disk machine modified. The results of effects the wear of UHMWPE inserts are not involved in this research, only those related to the design and adaptation of the new components to the wear of the pin-disc machine are presented as results of this work.

The main objective of this research is to obtain a useful computational model to know the mechanical response of a cranial distractor which is widely used in patients who have been affected by osteogenesis in craniosynostosis. As a part of an optimization of this model, the parametric parts and the assembly will be modified in order to adjust the system to the Mexican anthropometry. The research considers the influencing of the osteogenesis and the cranial deformation in childrens and adults, trying to recover the best shape from the cranial affected zone. Therefore, an engineering approach will be applied and the analysis of each one of the assembled parts, considering the specific geometry and mechanical properties of the commercial models. It will be reported in the context of numerical tests. It will allow the evaluation of the structural integrity and the customization. It aims to develop the design and finite element analysis of an adjustable vertical, horizontal, sagittal and occlusal vectors external distractor system. Two proposals that arise design by performing a device made in materials and manufacturing cost economize, but which in turn is reliable and meets the general requirements for patient treatment.

Mexico has a nuclear power plant with two BWR reactors. Their internal components were manufactured with type 304 stainless steel. Since the initiation of their commercial operation, some relevant cracks have been detected through the periodic inspections of their internals components. Specifically, there have been crack found at the core shroud and jet pumps. The causes of such cracks have been: excessive vibration, wear, stress corrosion cracking and residual stresses, acting alone or simultaneously. There are several aspects that have to be considered in the evaluation of the structural integrity of the core shroud, for instance: its shape is a cylinder and its R/t ratio is in the range between 60 and 100, as well as the water environment and the neutron irradiation. The last one has modified the mechanical properties of the material. Besides, each circumferential weld has a different non-symmetrical and irregular distribution of cracks with various depths. These cracks are monitored every 18 months, only during the plant shutdowns. Furthermore, the potential unstable cracking of the lower circumferential welds could induce important safety consequences if a loss of coolant accident and an earthquake event are postulated. Due to these reasons, it is very important to apply or develop adequate analytical procedures that can provide fast and reliable results. These procedures must cover elastic-plastic fracture analysis and plastic limit load analysis. In this paper, a methodology for the plastic limit load analysis was developed. The critical limit load for any crack distribution was calculated with a great degree of confidence. Operating conditions were considered. The shape of the cracks varies and the evaluation depends on the geometry of the cracked cylinder. In the problem at hand, the neutral axis varies, as it translates and rotates simultaneously at every cracked cross section, depending on the loading condition. This situation was also taken into account.

This paper presents results obtained on the harmful effect that a lamination process can cause in AISI 1018 steel during the manufacturing process of spring bed components in fire guns. The sequel presented by the induction of a residual stress field is analyzed as well. It has been established that the consequences produced by the residual stresses, could be minimized either by changing the geometric configuration of the component, or changing the manufacturing process, or regeneration of the microstructure of the material by heat treatment. This work analyzes the effects that consistently become apparent by the regeneration of the microstructure of the material, such as; level of the residual stress field, possible fracture and micro-structural changes. This article evaluates both the longitudinal and transverse residual stress that takes place during the punching process of the spring bed made of AISI 1018 steel. The Crack Compliance Method (CCM) for measurement the residual stress field was applied. Additionally, it is applied a micro-structural analysis of the component. A comparison between experimental results of grain size is shown. From this study it is possible to validate the correct behavior of the mechanical component and certify the expected useful life.

This paper reports a structural integrity analysis of a first human molar tooth. In this study, the loading condition caused by different sort of food was simulated. In order to cover a wide range, the resultant stress field evaluation was evaluated when a compressive load varied between 70N and 150 N. The finite element model was created using 3-D Computed Tomography and SCAN IP V.4 software. In the experimental analysis, reflective photoelasticity was used and the specimens were loaded with a Universal Testing Machine. The results show that stress concentrations are developed over the crown surface. The range of the top von Mises stress, for the loading cases mentioned above, is between 1.05 MPa and 3.46 MPa. The tooth geometry distributes gently the resultant stress on its root.

In this paper, the interaction among cervical vertebrae, a cervical plate and a bone graft implant, which is developed in a Corporectomy, is analyzed in an experimental form. In the case of specific damaged vertebra, its replacement is one of the alternative solutions. However, the displacement between the vertebral adjacent facets and the bone graft is a critical parameter which has to be evaluated in order to ensure the stability of the spine. Besides, it is advisable to make a precise evaluation of the structural integrity of the arrangement. For this study, porcine cervical vertebrae (C3-C5) were instrumented in order to replace a damaged C4 vertebra. This arrangement was tested under compression. The experimental observations were complemented with a numerical model. The displacements between the vertebral facets and the bone graft were measured. They are lower than 3 mm in order to develop stability in the spine. Besides, the proposed arrangement has structural integrity and the surgical procedure is simplified, as no wires are used.