Christopher René Torres-San Miguel

Mechanical Design of a Prosthetic Human Arm and its Dynamic Simulation

In this paper the mechanical design of a prosthetic human arm with 7 DOFs that includes the shoulder, elbow and wrist is presented. The objective of this design is to have an anthropomorphic, functional and low cost prosthesis. A set of dynamic simulations were performed to determine the feasibility of the mechanism as well as the torque required to perform the activities. The results show that the design could be a good solution due to the physical characteristics and the kinematic of the system.

Strain Measurements Exhibited by a Steel Prosthesis Protected with Au Nanoparticles

The design and manufacturing of a customized femur prosthesis is presented. Besides, the application of a coating of Au nanoparticles embedded in titanium dioxide is evaluated. For this purpose, a customized femur prosthesis for a Labrador Retriever dog was manufactured. It was 7 years old and its weight was 35 kg. The main geometrical characteristics of the prosthesis are the following. Its femoral neck angle is 75.84°, the smallest and largest diameter of the shaft is 2.7 and 6 mm, respectively, while the diameter of the femur head is 20 mm. The material used for this purpose was stainless steel. Initially, a tomographic study of the hip and femur was carried on. All the data was collected in .DICOM files. From this information, solid models were obtained. The new data was saved in .STL files. From such files, quick prototypes were carried out. They were made with ABS material, following a stereolithography procedure. All the dimensions were checked. Once the customized model was approved, the structural integrity was determined with the finite element method. In the next step it was manufactured. In the final part, a 250 nm coating, which was made of Au nanoparticles embedded in titanium dioxide, was applied. An indentation test was carried out. A 65° Berkovich indenter, made with diamond, was used. The modulus of elasticity of the coating was 941 MPa. The stress field during the indentation test was obtained.

New Procedure to Construct an Anisotropic Elastic FE-Model Based on Swine Femoral Bones Using Numerical Modeling

This work presents a new procedure to determine the density of bone tissue from collected data by means of computed axial tomography (CAT) and bone density correlations of cancellous and cortical tissue with their elastic properties which were obtained from structure reconstruction software to determine the apparent density of bone. The main objective is to determine the anisotropic elastic properties in swine femoral bones on two orthogonal directions to produce a most real behavior of bone FE-model. A TC Brilliance axial scanner (tomograph) was used to obtain the desired images, which were then processed in the Digital Imaging and Communication in Medicine format using different software packages, including Scan IPTM, Scan FE v3.1TM, and ANSYS vl2 TM. Five Duroc-Jersey type swine femur specimens were used for the analysis. These specimens are considered to be equivalent to human specimens of 50 to 55 years of age, since they have been used for eighteen months in experimental processes. The experimental procedure included the processing of 60 tomographic cuts, which allowed the determination of the zone where the density maximum and minimum values of the bone tissue seem to be located. The results obtained displayed the anisotropic elastic behavior for each bone specimen within a voxel unit of precision. The findings of this study could allow a significant advance in the development of customized endo-prostheses by determining the elastic properties of the bone and developing more accurate FE-models. This will contribute to the improvement of the performance of artificial implants as well as to increasing the service life of these prostheses.

Numerical Analysis of the Knee Articulation Leg. The Angular Position Parameters and Forces Acting on the Joint Were Obtained and Applied into the Corresponding, During Different Stages of the Gait Process

The knee is a diarthrodial joint or a wide mobility joint (or a wide mobility joint), which involves an extremely complex mechanical analysis. The knee possesses a great stability in complete extension to support the corporal weight, and has the necessary mobility to perform diverse daily activities (jump, gait, trot, run, among others) and efficiently orients the foot in relation to the irregularities of the ground. At present, a general understanding is possessed of the forces acting onto the bone structural components of the knee joint during daily activities. On the other hand, by applying Finite Element algorithms it is possible to numerically simulate the anatomic systems that constitute the human body. This algorithm has turned out to be an important tool to determine research behavior of the bone is not an organism, to determinate the behavior of bones from a mechanical point of view. Additionally, they are applied as a foundation for prosthesis design and numerical model generation to solve problems related to clinical conditions. For example, the degenerative osteoarthritis of the knee is a chronic degenerative disease that is active in persons between the ages of 50 to 60 years old and involves severe wear of the joint. This condition can be accelerated by multiple circumstances, the main one big effect of articulated overload (obesity, knee deformation, meniscus injuries, among others). In this paper we propose that a static structural analysis of the knee joint, which involves three phases of the human gait: normal support, contact (foot-ground) and balancing of the leg. The angular position parameters and the forces acting on the joint were obtained, and applied into the corresponding numerical analyses for each gait phase. The numerical analyses are based on the kinetic and kinematic studies of the knee, to determine the orientation and range of mobility of the joint. The numerical model of the knee joint was developed from a Computed Axial Tomography scan which would assure bio-fidelity in the numerical evaluation. Obtaining as results: the von Misses equivalent stress, the maximum and minimum principal stresses and the total displacement. It was determined by this research, that the knee capacity to support the loads in each step of the gait process and it helped to establish a data base for the design and development of joint knee prosthesis.

Design and Manufacture of a Forearm Prosthesis by Plastic 3D Impression for a Patient with Transradial Amputation Applied for Strum of a Guitar

At the present, the development of prostheses has been extremely wide and focused on restoring the patient to their daily activities. Nevertheless, not much has been done to restore the capability of playing musical instruments, perhaps due to the complexity and sensibility needed to perform certain movements. For example, the fingering movements on a guitar or a piano, are random and require of different amounts of force to be applied to the instrument. Furthermore, the playing of an instrument is accomplished by muscular memory. Nowadays, in order to emulate such movements, the application of robotically programmed prostheses has improved. Nevertheless, this is not a good option for musicians, as this solution do not offer the sensation of actually playing the instrument. One of the options to achieve the mentioned aim, would be the development of mechanical prostheses that apply myoelectric technology, however these devises do not possess sufficient sensibility to perform the movements needed to play an instrument. In this research, a mechanical design to be manufactured using 3D impression of a forearm prosthesis for a transradial amputated patient that is able to be used to play the guitar, is presented. The prosthesis is capable to provide the service for basic rehabilitation or train a recently amputated patient recently amputated. The proposed prosthesis was manufactured by the use of a plastic 3D impression machine using ABS-P400 strings. The prosthesis consists of two parts; the first one is the main socket that is attached to the forearm while the second part, that supports the nib guitar. The mechanical design of the prosthesis was based on data obtained by videometry of a musician developing the basic strum on a guitar. With these data was possible to define the basic strum technique, the movements that are involved (displacements, speed, acceleration, forces, etc.) and the joints involved in the strum of a guitar. The obtained results are very encouraging, since the prosthesis can be applied to restore the musician ability to perform the basic tasks to execute on his instrument, as well as, rehabilitation activities. This first proposal could be optimized to produce a final product with higher quality and with a wider area of applicability.

COMPARACIÓN NUMÉRICA DEL HIC (HEAD INJURY CRITERION) EN CONDICIONES DE ATROPELLO A DIFERENTES VELOCIDADES CON UN VEHÍCULO TIPO SEDÁN

An injury mechanism is defined as a description of the mechanical and physiological changes that result in anatomical and functional damage in the human being. The mechanisms of head injury have been studied through the use of animal experiments, PMHS (Post Mortem Human Subjects), physical models and models developed using Finite Elements.

Research Advances and Perspective of Multi-Articulated and Robotic Hands

The development of prostheses for upper limbs is extensive and complex. Actually, the results obtained by our group in the design on a multiarticulated hand prosthesis are encouraging. Its design has to satisfy essential functions for the development of various activities. Besides, such prosthesis has to be versatile and a high precision in the execution of movements has to be satisfied. On the other hand, amputation of one extremity at any level, definitely, affects the quality of life of an individual, inducing a high emotional impact. In this chapter, an overview of the development of hand prostheses is provided. Main aspects of the state of art are mentioned. In the second part, the technological developments involved in the implementation of a multiarticulated hand prosthesis and robotic fingers by our group are discussed. With this information, the future trends in the design of robotic hands and the application of evolutive algorithms in the design of hand prostheses are discussed.

Numerical Simulation on the Residual Stress Induction due to Welding Process and Assessment by the Application of the Crack Compliance Method

Residual stresses are mechanical effects that remain in a body after all external loads have been removed. In this sense and because a weldment is locally heated by a welding heat source, the temperature distribution is not uniform and changes as welding progresses. During the welding thermal cycle, complex transient thermal stresses are produced in the weldment and the surrounding joint. With the advancement of modern computers and computational techniques (such as the finite-element and the finite-difference methods), a renewed effort has been made in recent years to study and simulate residual stresses and the related phenomena. This paper discusses the procedure applying a finite element analysis by a 2D model to determine the residual stresses and distortions of steel AISI 316 bars under an arc welding process; additionally, the state of the stresses in the component is determined by the application of the crack compliance method (CCM); this is destructive experimental method based on fracture mechanics theory. This research also demonstrates that the residual stress distribution and the magnitude inducted into the component must be carefully assessed, or it could result in a component susceptible to failure.

Performance of Simple Genetic Algorithm Inserting Forced Inheritance Mechanism and Parameters Relaxation

Genetic Algorithms are a search paradigm that applies principles of evolutionary biology (crossover, mutation, natural selection) in order to deal with intractable search spaces. The power and success of GA are mostly achieved by the diversity with the individuals of a population which evolve, in parallel, following the principle of the survival of the fittest. In general, the genetic algorithms resolve combinatorial optimization problems that in (Goldberg, 1989) are mentioned, this implies a large number of responses associated with an exponential growth in solutions potentially feasible according to the magnitude of the problem. In a standard GA the diversity of the individuals is obtained and maintained using the genetic operators crossover and mutation which allow the GA to find feasible solutions and avoid premature convergence to a local maximum (Holland, 1975).