José Jaime García

Universidad del Valle (Colombia) | UNIVALLE · School of Civil and Geomatic Engineering

The construction industry is undergoing a transformation towards automation, and 3D printing is at the forefront of this revolution. However, to optimise 3D printing in construction, it is crucial to consider the printer’s scale, the printing material’s rheological properties, and the printed structure’s mechanical properties. This paper provides a...

Physics-based modeling methods have the potential to investigate the mechanical factors associated with knee osteoarthritis (OA) and predict the future radiographic condition of the joint. However, it remains unclear what level of detail is optimal in these methods to achieve accurate prediction results in cohort studies. In this work, we extended...

Motion data from an ACL-reconstructed subject was utilized to inform a personalized musculoskeletal (MS) model simulating a representative stride under normal and biofeedback-driven walking. A subsequent MRI-based finite element (FE) model served to simulate the cartilage stresses during the stance. As a result, the exposure of the medial tibial ca...

Guadua angustifolia is a bamboo species that has been used in construction since it is an excellent sustainable material. However, it creeps under sustained loading, modifying the structural behavior of culms and joints. Thus, this study was aimed at describing the creep behavior of Guadua on the transverse plane. To this end, 60 Guadua rings were...

Computational models can be used to predict the onset and progression of knee osteoarthritis. Ensuring the transferability of these approaches among computational frameworks is urgent for their reliability. In this work, we assessed the transferability of a template-based modeling strategy, based on the finite element (FE) method, by implementing i...

We developed a novel knee joint model in FEBio to simulate walking. Knee cartilage was modeled using a fibril-reinforced biphasic (FRB) formulation with depth-wise collagen architecture and split-lines to account for cartilage structure. Under axial compression, the knee model with FRB cartilage yielded contact pressures, similar to reported experi...

Stress-relaxation tests on Guadua angustifolia rings were conducted to determine the behavior under sustained transverse loading. A generalized Maxwell's model with three parameters showed good accuracy in fitting the experimental data. However, a significant dispersion of model parameters was observed. Thus, the Scott-Blair fractional derivative m...

Relaxation tests of rings, semirings (SR) and C specimens (part of rings like the letter C) of Guadua angustifolia were used to characterize the mechanical behavior of the material under sustained transverse displacement. Tests shorter than one hour showed a behavior typical of viscoelastic materials, described by the initial raise of the force fol...

Osteoarthritis (OA) is a degenerative disease that affects the synovial joints, especially the knee joint, diminishing the ability of patients to perform daily physical activities. Unfortunately, there is no cure for this nearly irreversible musculoskeletal disorder. Nowadays, many researchers aim for in silico-based methods to simulate personalize...

Bamboo is a sustainable material with a high potential to replace high-contaminating materials such as steel and concrete in many uses. However, some properties, such as the resistance to pests and dimension stability, must be improved for bamboo to be accepted by the engineering community. A low-cost way to improve dimension stability and resistan...

Convection-enhanced delivery (CED) is a promising method to deliver therapeutic drugs directly into the brain that has shown limited efficacy, mainly attributed to backflow, in which the infused drug flows back along the needle track rather than forward into tissue. This study evaluates the effect of sharp and blunt needle tips on backflow length u...

This paper reports the design of an innovative mono-lateral external fixator made of carbon fiber composite materials. The designed system can be easily assembled in comparison with commercial fixators and follows orthopedic requirements with sufficient stability and stiffness. The change of operation mode between distraction and fixation is achiev...

There is a growing recognition and awareness that nature can provide viable solutions for more sustainable building materials. Arundo donax (AD) is a tall cane of about 20–30 cm in diameter that grows widely and rapidly in many regions of Europe. AD, like bamboo in the subtropical areas, may be rediscovered as a source of inexpensive sustainable ma...

Convection-enhanced delivery is a technique to bypass the blood–brain barrier and deliver therapeutic drugs into the brain tissue. However, animal investigations and preliminary clinical trials have reported reduced efficacy to transport the infused drug in specific zones, attributed mainly to backflow, in which an annular gap is formed outside the...

Bamboo is a functionally graded and axially reinforced material displaying high longitudinal mechanical properties. However, it is prone to longitudinal splitting, mainly due to tensile and shear stress components. Therefore, this experimental study was focused at determining the transverse mechanical properties of five species of bamboo using digi...

Convection-enhanced delivery (CED) is a technique to bypass the blood-brain barrier and deliver therapeutic agents into the brain. However, animal studies and preliminary clinical trials have reported reduced efficacy to transport drugs in specific regions, attributed mainly to backflow, in which an annular zone is formed outside the catheter and t...

Bamboo is a natural sustainable material with a high potential to substitute high contaminating construction materials in various applications. It is a heterogeneous material axially reinforced with cellulose fibers that confers high axial mechanical properties. However, it is prone to longitudinal fissures, mainly due to tensile and shear stress c...

Bamboo has become a promising sustainable material for structural applications. The design of normalized efficient connections is one challenge that has to be solved to increase the use of raw bamboo in construction. Current bamboo connections are considered to be unable to transmit moment, limiting the use of the material in several applications....

We developed a monolateral external fixation system for bone elongation easier to assemble than commercial systems since the clamps can be laterally assembled to the rail in contrast to the commercial systems where the clamps can only be assembled from the ends. The system is formed by clamps, screws, and a rail. The rail is composed of two carbon...

This study pertains to the design and structural testing of trusses assembled with culms and slats of the bamboo species Guadua angustifolia (GA). The trusses were constructed using a novel design of steel clamps to accomplish the connections between the top and bottom chord culms and the diagonal and vertical slat elements. The clamps offer a bett...

Guadua angustifolia Kunth (GAK) is the most common bamboo species in Colombia. As a material, it is well recognized for its high axial strength, lightness, low cost and tubular cross section. Therefore, it has a great structural potential. Additionally, it is an alternative to reduce the high pressure to the forest exploitation and the use of tradi...

Bamboo is highlighted by its high axial strength, lightness, tubular shape and high sustainability. Bamboo connections cannot be easily built due to the hollow cylindrical shape and the high dimensional variation and transverse weakness of the culms, which tend to fail by longitudinal splitting. Joints recommended by the Colombian construction code...

The development of a new simple test method suitable for assessing the tension strength perpendicular to the fibres (Mode I) of a bamboo culm-the flat ring flexure test-is presented. The proposed test places a short section of bamboo culm in through-cross section flexure, which causes circumferential stresses at failure. The modulus of rupture at t...

El libro se ha organizado de manera que cada capítulo puede ser leído independientemente. En el Capítulo 2 se incluye una breve descripción de la anatomía de la columna vertebral y luego una revisión de los trabajos experimentales y de los modelos teóricos más relevantes sobre el tema. El Capítulo 3 detalla los procedimientos usados para, a partir...

Guadua angustifolia is a species of bamboo native to South America. The aim of this study was to accomplish experiments and finite-element simulations to determine the stiffness of two-culm G. angustifolia beams, as typically used in the construction of low-rise buildings. Calculations were also accomplished to find the moment of inertia (i.e. effe...

Khosrow Ghavami and José Jaime García, editors of a themed issue of the Institution of Civil Engineers’ Structures and Buildings journal on bamboo, say four decades of research and development mean it can now be safely used instead of steel and concrete in many applications.

Purpose: The intervertebral disc supports axial and shear forces generated during tasks such as lifting and carrying weights. The objective of this study was to determine the forces in the lumbar spine of workers carrying a bag on the head, on the shoulder, and on the anterior part of the trunk. Materials and methods: Kinematic measurements were re...

Currently, construction tendencies tend to design flexible structures, such as footbridges, slabs and grandstands, due to the increased resistance of new materials and the regulation gap in building codes. These flexible structures are susceptible of excessive vibrations induced by human activities, producing serviceability failures and, sometimes,...

Guadua angustifolia is a species of bamboo exhibiting excellent mechanical properties in the axial direction, which have been extensively investigated. Few studies have measured other anisotropic constants, which are necessary for reliable theoretical analyses. A simple new protocol is proposed to determine the circumferential–axial shear modulus a...

Purpose: A probabilistic finite element (FE) analysis of the L4-L5 and L5-S1 human annulus fibrosus (AF) was conducted to obtain a better understanding of the biomechanics of the AF and to quantify its influence on the range of motion (ROM) of the L4-L5 and L5-S1 segments. Methods: The FE models were composed of the AF and the upper and lower en...

Bamboo is a sustainable material with high potential for structural applications. The aim of this study was to use edge bearing tests, digital image correlation analysis, and finite element simulations to research about the distribution of the circumferential elastic modulus through the wall and the associated failure strain and stress. Studied bam...

Guadua angustifolia (GA) is the most common bamboo species in Colombia. It is a fast growing plant that has a good capacity to sequester carbon, regulate water cycles, and control soil erosion. It has a high potential as a structural material due to its low density and cost, tubular shape and specific strength similar to that of a low carbon steel....

Guadua angustifolia (GA) is a species of bamboo native of South and Central America. It is a fast growing plant and thus its controlled use does not threat the natural plantations, which play an important role to control water cycles, to reduce erosion and to sequester carbon. Traditionally, GA has been used to construct rural houses and temporary...

The two aims of this study were to generate data for a more accurate calibration of finite element models including the L5-S1 segment, and to find mechanical differences between the L4-L5 and L5-S1 segments. Then, the range of motion (ROM) and facet forces for the L4-S1 segment were measured using the stepwise reduction method. This consists of seq...

Agarose hydrogels have been extensively used as a phantom material to mimic the mechanical behavior of soft biological tissues, e.g. in studies aimed to analyze needle insertions into the organs producing tissue damage. To better predict the radial stress and damage during needle insertions, this study was aimed to determine the friction coefficien...

Guadua angustifolia (GA) is an American species of bamboo. It is a sustainable anisotropic material that exhibits high strength along the longitudinal direction of the culm and low strength on the planes of the fibers, which usually leads to premature fissures and failure in the joints of GA structures. Based on the ductile behavior of the material...

With the aim to study disc degeneration and the risk of injury during occupational activities, a new finite element (FE) model of the L4-L5-S1 segment of the human spine was developed based on the anthropometry of a typical Colombian worker. Beginning with medical images, the programs CATIA and SOLIDWORKS were used to generate and assemble the vert...

Convection-enhanced delivery (CED) is a technique to deliver controlled amounts of drugs directly into the brain for the treatment of tumors and diseases such as Parkinson’s. Several CED animal studies have shown encouraging results for drug distribution. However, clinical trials have reported low efficacy of CED, primarily due to the poor distribu...

Guadua angustifolia (GA) is a species of bamboo indigenous of South and Central America. It is a fast growing plant and thus its controlled use does not threat the natural plantations, which play an important role to control water cycles, to reduce erosion and to sequester carbon. It is a fiber reinforced anisotropic sustainable material that has b...

Introduction Convection enhanced delivery (CED) is a method to deliver controlled amounts of drugs over target zones into the brain and bypass the blood-brain barrier for the treatment of diseases and tumors. However, there is a problem during infusions called backflow that consist the drug flows through the interface needle-tissue. Several experi...

Convection-enhanced delivery as a means to deliver therapeutic drugs directly to the brain has shown limited clinical efficacy, primarily attributed to the phenomena of backflow, in which the infused fluid flows preferentially along the shaft catheter rather than forward into the tissue. We have previously developed a finite element model of backfl...

The mechanical properties of human brain tissue are the subject of interest because of their use in understanding brain trauma and in developing therapeutic treatments and procedures. To represent the behavior of the tissue, we have developed hyperelastic mechanical models whose parameters are fitted in accordance with experimental test results. Ho...

A previously proposed finite element model that considers geometric and material nonlinearities and the free boundary problems that occur at the catheter tip and in the annular zone around the lateral surface of the catheter was revised and was used to fit a power-law formula to predict backflow length during infusions into brain tissue. Compared t...

The bamboo species Guadua angustifolia is a natural functionally graded material with a high potential to help solving the housing deficit in Latin American countries. Bamboo plantations also play an important role to help reducing the devastation of tropical forests. Many studies have demonstrated the excellent mechanical properties of bamboo alon...

According to the traditional theory of elasticity, the total deflection of a beam occurs due to the combined effect of both the bending moment and the shear force. In isotropic materials such as steel and concrete, the deflection due to shear is usually not taken into account since it represents only 1% of the total deformation approximately. Howev...

con el objeto de conocer la capacidad de predicción de los modelos de elementos finitos de materiales poroelásticos, se validó un modelo simplificado del disco intervertebral de la columna, con valores experimentales obtenidos de modelos construidos con materiales artificiales. Los discos artificiales, construidos con un núcleo de espuma de poliure...

Convection enhanced delivery is a protocol to deliver large volumes of drugs over localized zones of the brain for the treatment of diseases and tumors. Brain infusion experiments at higher flow rates showed backflow, in which an annular zone is formed outside the catheter and the infused drug preferentially flows toward the surface of the brain ra...

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Convection-enhanced delivery is a technique to infuse therapeutic agents into the brain under positive pressure for the treatment of disorders of the central nervous system. Recent clinical trials [1] have shown limited efficacy of this procedure, attributed to poor distribution of the infused agent that may be due to backflow, in which the infused...

Initial experimental characterization of brain tissue assumed it was a single-phase material and modeled the nonlinear mechanical behavior observed under finite deformation using the incompressible Ogden strain energy function. For the modeling of some diseases of the brain, it is necessary to represent brain tissue as a biphasic medium with solid...

A biphasic model for noncommunicating hydrocephalus in patient-specific geometry is proposed. The model can take into account the nonlinear behavior of brain tissue under large deformation, the nonlinear variation of hydraulic conductivity with deformation, and contact with a rigid, impermeable skull using a recently developed algorithm. The model...

An axisymmetric biphasic finite element model is proposed to simulate the backflow that develops around the external boundary of the catheter during flow-controlled infusions. The model includes both material and geometric nonlinearities and special treatments for the nonlinear boundary conditions used to represent the forward flow from the cathete...

Spine finite element models are an essential tool to study the degeneration of the intervertebral disc (IVD). Due to the complex geometry of the vertebras, the anisotropy and heterogeneity of the tissues, and the contact and material nonlinearities [1], spine models demand high computational resources. Considering the relatively low stiffness of th...

In a healthy brain, a continuous flow of cerebrospinal fluid (CSF) is produced in the choroid plexus, located in the lateral ventricles. Most of the CSF drains via the Sylvius aqueduct into the subarachnoid space around the brain, but a small amount flows directly through the cerebrum into the subarachnoid space inside the skull. Non-communicating...

Convection-enhanced delivery (CED) is a means to deliver therapeutic agents directly into brain tissue for the treatment of brain tumors and other disorders of the central nervous system, such as Parkinson’s disease. Recent clinical trials have shown limited efficacy of this procedure, with poor distribution of the infused agent being the primary o...

Different species of bamboo are extensively used to build houses and temporary structures in developing countries. Few studies have been carried out to establish the elastic constants along the transverse axes which are the weakest directions, making them prone to failure. This is mainly due to the difficulty to cut specimens long enough to accompl...

A nonlinear, coupled biphasic-mass transport model that includes transvascular fluid exchange is proposed for flow-controlled infusions in brain tissue. The model accounts for geometric and material nonlinearities, a hydraulic conductivity dependent on deformation, and transvascular fluid exchange according to Starling's law. The governing equation...

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Se presenta la caracterización mecánica de un nuevo fijador unilateral multiaxial de bajo costo (ATLAS) desarrollado por nuestro grupo. Éste es un fijador de urgencias de doble barra, en el que se utilizan conectores que permiten seis grados de libertad entre las barras y los clavos que conectan, con lo cual se pueden activar también los seis grado...

A biphasic nonlinear mathematical model is proposed for the mass transport that occurs during constant flow-rate infusions into brain tissue. The model takes into account geometric and material nonlinearities and a hydraulic conductivity dependent upon strain. The biphasic and convective-diffusive transport equations were implemented in a custom-wr...

ATLAS is an external bone fixation system developed by the Grupo de Biomecánica of the Universidad Del Valle with the purpose to make it affordable to a wide spectrum of the population. The experimental and analytic characterization is presented of two nonconvectional and widely used configurations of the system, which were subjected to static and...

Con base en la forma débil de las ecuaciones no lineales que describen el comportamiento mecánico de materiales bifásicos, presentadas en la Parte I, en esta segunda parte se describe la implementación numérica y solución de las ecuaciones para problemas con simetría axial mediante el método de Newton y un procedimiento de integración paso a paso e...

A biphasic hyperelastic model with spherical symmetry is presented to study hydrocephalus. The model can take into account the biphasic nature of brain tissue, non-linear stress-strain curves through an Ogden-type compressible strain energy function, a nonlinear variation of hydraulic conductivity with deformation, a constant production of cerebros...

Convection-enhanced delivery is a means to deliver therapeutic agents directly into brain tissue. Biphasic models have been used to study the concomitant fluid and mass transport that occurs during infusion, however previous studies have been limited by the assumption of linear elasticity of the solid phase [1]. In contrast, nonlinear stress-strain...

To date, studies that have investigated the kinematics of spinal motion segments have largely focused on the contributions that the spinal ligaments play in the resultant motion patterns. However, the specific roles played by intervertebral disk components, in particular the annulus fibrosus, with respect to global motion is not well understood in...

Resumen. Los sistemas de fijación externa son herramientas de uso cotidiano para el tratamiento de fracturas complejas ocurridas en accidentes de tránsito. A diferencia de otros sistemas comerciales, el sistema de ATLAS, desarrollado en el seno del Grupo de Biomecánica de la Universidad del Valle, está basado en la utilización de prensas que permit...

A biphasic nonlinear mathematical model is proposed for the concomitant fluid transport and tissue deformation that occurs during constant flow rate infusions into brain tissue. The model takes into account material and geometrical nonlinearities, a hydraulic conductivity dependent on strain, and nonlinear boundary conditions at the infusion cavity...

The delivery of therapeutic agents into the brain is impeded by the blood-brain barrier, preventing adequate treatment of diseases of the central nervous system. Convection enhanced delivery was developed as a means to deliver therapeutic agents directly into brain tissue and to transport the drugs in the extracellular space using convective flow....

Models to represent the mechanical behavior of the annulus fibrosus are important tools to understand the biomechanics of the spine. Many hyperelastic constitutive equations have been proposed to simulate the mechanical behavior of the annulus that incorporate the anisotropic nature of the tissue. Recent approaches [1,2] have included terms into th...

A biphasic hyperelastic finite element model is proposed for the description of the mechanical behavior of brain tissue. The model takes into account finite deformations through an Ogden-type hyperelastic compressible function and a hydraulic conductivity dependent on deformation. The biphasic equations, implemented here for spherical symmetry usin...

This paper describes designing and constructing a test machine having a 1,800 N capacity and maximum 3 Hz frequency which will be used in static and dynamic testing of biological tissues and orthopedic devices such as external fixers. It consists of an octagonal base with 500 mm distance between faces and a crosshead which slides between two column...

Analyses with a finite element fibril-reinforced hyperelastic model were undertaken in this study to simulate high tensile Poisson's ratios that have been consistently documented in experimental studies of articular cartilage. The solid phase was represented by an isotropic matrix reinforced with four sets of fibrils, two of them aligned in orthogo...

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

This paper describes designing and constructing a test machine having a 1,800 N capacity and maximum 3 Hz frequency which will be used in static and dynamic testing of biological tissues and orthopedic devices such as external fixers. It consists of an octagonal base with 500 mm distance between faces and a crosshead which slides between two column...

Bamboo is a highly anisotropic natural material widely used in structural applica- tions. A transversely isotropic constitutive equation is proposed here as the simplest law able to capture main anisotropic features of bamboo. Diametric compression tests were