This paper covers finite element (FE) analysis and optimization of a spring orthosis, constructed from a pre-impregnated carbon-fibre epoxy composite material. The spring orthosis is one of the most advanced aids that are used in the orthopedist industry. The work has been performed in collaboration with Ortopedteknik, Borås Hospital, at FS Dynamics in Gothenburg. The purpose of the analyses was to find weaknesses of how the orthosis is built today and to give suggestions of how to change its properties and behaviour. The orthosis has two major interesting areas, the spring and the toe.
Biomechanics testing of the lumbar spine, using cadaveric specimens, has the advantage of using actual tissue, but has several disadvantages including variability between specimens and difficultly acquiring measures such as disc pressure, bone strain, and facet joint contact pressure. A simulation model addresses all of these disadvantages. The objective of this work is to develop a method to simulate the biomechanics of the lumbar spine. A process is currently being used to convert a CT scan of a lumbar spine into a simulation model.
Total knee replacement gives proven good results for isolated patello-femoral osteoarthritis, but patello-femoral arthroplasty may be more appropriate because only the joint compartment is replaced. Although the femoral component of a patello-femoral prosthesis is smaller than in total knee arthroplasty, it is unknown whether strain-adaptive periprosthetic bone remodeling occurs following patello-femoral arthroplasty. The aim of the study was to evaluate and compare the stress shielding effect of prosthetic replacement with Finite Element (FE) modeling.
Genetic algorithms have become one of successful tools in design and topology optimization. The optimization module based on genetic algorithms was developed and employed in Abaqus/CAE by GUI and kernel scripting. The new module extends advanced functionality of Abaqus/CAE allowing to perform optimization directly in Abaqus Unified FEA product suite from SIMULIA. The genetic algorithms implemented in optimization approach are based on available GPL libraries.
In this study we compare various way of quantifying high cycle radial fatigue behavior in a percutaneous Mitral repair device using Goodman methods. In order to provide an improved representation of the tissue-device interaction, we use an Ogden hyperelastic model to simulate the native vessel with parameters obtained from pressure-diameter test data of human cadaver heart coronary tissue, and published data presented in previous work.
Prediction of respiratory motion has the potential to substantially improve cancer radiation therapy. A nonlinear finite element (FE) model of respiratory motion during full breathing cycle has been developed based on patient specific pressure-volume relationship and 4D Computed Tomography (CT) data. For geometric modeling of lungs and ribcage we have constructed
Computational modeling of stents can provide insight into critical locations (high stress/strain regions), help with design iterations/optimization, and reduce the need for bench-top testing. This study focuses on the developmental efforts to create a material model that can capture the mechanical response of poly-L-lactide (PLLA), the backbone of Abbott Vascular’s ABSORB Bioresorbable Vascular Scaffold (BVS). PLLA is an anisotropic, viscoplastic material.
Endovascular aneurysm repair involves insertion of an introductory component called guidewire through native vessels to help with the guidance of the delivery catheter. Guidewire tends to alter the vessel geometry due to its higher stiffness compared to the vessel wall. Very limited data is available to understand such interactions. Investigation of interaction between guidewire and native vessels could provide useful insight into vessel stresses and guidewire deformation in-vivo.
To enhance the fatigue life of metal components, frequently compressive stress is introduced to the surface layer. Although procedures such as shot peening have been practiced for many decades in other industries, an improved understanding of the fundamental mechanics that leads to the improved performance is desired. From a continuum mechanical point of view, the interaction between the crack and the stress intensity field is the factor determining whether the crack will propagate.
The stresses in a battery housing used in Implantable Pulse Generators (IPGs), also known as pacemakers, were investigated using Abaqus/Standard. There were three levels of analysis: the global level, the three-dimensional submodel level and the plane strain submodel level. The output of the global analysis was fed into the three-dimensional submodel analysis and subsequently the output of the three-dimensional submodel analysis was fed into the plane strain submodel analysis.
Cataract surgery is the most common surgery in America today. Modern surgeries require the opacified crystalline lens to be removed and for a prosthetic lens to be inserted through a suture-less incision during a 5-10 minute outpatient procedure. The industry is driving for smaller incisions by redesigning the lens and insertion device geometry in addition to new materials. Typical lens dimensions are 6mm diameter with a center thickness of 1mm which is inserted through a 2.8mm incision. For the insertion the lens is folded and elongates while advancing down a tapering tube.
The fracture of the proximal humerus is the second most common injury to the upper extremity. In severe fractures, surgery may be necessary which can be in the form of a locking plate holding the bones in place. This study examines the effect of including a bonegraft alongside the locking plate. ScanIP and +ScanCAD (Simpleware Ltd) were used to segment the proximal humerus from a CT scan, and to introduce CAD data of the fixation plate and bonegraft.
Stents have been used in the treatment of coronary artery disease for decades, and their use in the peripheral arterial vasculature is growing rapidly. Mechanical loads imposed on peripheral stents may include loads due to arterial pulsation, axial compression, bending and torsion. These stents are most often manufactured using nitinol, a nickel-titanium alloy that exhibits unique shape memory and superelastic characteristics. Finite element analysis can be a powerful tool in designing medical devices to withstand such a rigorous loading environment.
Due to concerns over particle generation in conventional metal-on-polyethylene hip bearings used in total hip arthroplasty (THA), interest in advanced low-wear bearing alternatives such as ceramic-on-ceramic (CoC) couples has reemerged. While ceramics demonstrate excellent
An understanding of functional responses in oral bone is a crucial component of dental biomechanics. The purpose of this study was to investigate the use of an osseointegrated implant as support for a free-end removable partial denture (RPD) on the potential biological remodelling response during mastication. A three-dimensional (3D) finite element analysis (FEA) was performed to determine the biomechanical responses to masticatory loading in the posterior mandible.
A person specific drop foot brace was simulated in the commercial finite element code Abaqus.The geometry was imported from a 3D optical scan of the actual surface and modeled as a composite material layup defined in a local discrete material coordinate system. The finite
element model was used in order to model the stance phase in a normal walking. The material
choice is a challenging task giving flexibility to the brace together with sufficiently stiffness and
fatigue strength. The simulation has been compared with measurements from a strain gauge
mounted foot brace tested in use. Based on simulations, a large number of expensive trial and
For clinicians and medical device manufacturers, in-vitro and in-vivo testing of the knee are important methods for evaluating treatment techniques. However, numerical models that can provide much of the same information will become of more service and are a new focus of the modeling community. A continued effort has centered on specimen-specific anatomical and functional models, in terms of both geometry and mechanical properties of the tissue constituents.
A variety of polymers are used extensively for both medical applications and consumer products. Most of these polymers exhibit time-dependant behavior which varies significantly with environmental conditions. Injection molding technologies generally offer application design freedom and options for several functions build into each component. Meanwhile analysts are often faced with the difficulties of predicting the response of the final product.
Numerical methods applicable to the tibia bone and soft tissue biomechanics of an ACL reconstructed knee are presented in this paper. The aim is to achieve a better understanding of the mechanics of an ACL reconstructed knee. The paper describes the methodology applied in the development of an anatomically detailed three-dimensional ACL reconstructed knee model for finite element analysis from medical image data obtained from a CT scan. Density segmentation techniques are used to geometrically define the knee bone structure and the encapsulated soft tissues configuration.
As the maximum speed of bullet trains continues to increase, overheating and thermal deformation/stress on brake systems are going to be critical for emergency stops. Precise prediction of the maximum temperature is needed for the design of brake systems, especially for both discs and linings, where how to handle the high speed spinning of discs is the point of the heat/structure coupled analyses. Abaqus provides couple of potential methods but each one had critical shortcomings.
Electrically operated high temperature furnaces and reactors are used in many industrial
manufacturing processes such as sintering or single crystal growth in order to allow for the
required process conditions. In view of their outstanding characteristics refractory metals are
Today manufacturing companies are more and more often characterized by a growing product
and processes complexity. Projects needs the participation of a pool of companies that have to
collaborate in a multidisciplinary and integrated way following a defined PLM strategy.
These challenges are meant to introduce a new way of working, based on innovation and
global collaboration, both internally among different disciplines and externally between
operations, administration, and maintenance and its suppliers. The development engineering
Carbon-fiber-reinforced plastics (CFRP) are being used for highly loaded lightweight structural components for many years. Up to now mostly insufficient two-dimensional classical failure criterions, which are embedded into FE-software like Tsai-Wu, Hill, etc. have been used for the dimensioning of composites. To achieve better predictions of the three-dimensional complex composite failure behavior newer, so-called action-plane based failure criterions have been developed, e.g.: PUCK, JELTSCH-FRICKER or LaRC04.