Refine
Year of publication
Institute
- IfB - Institut für Bioengineering (602)
- Fachbereich Medizintechnik und Technomathematik (522)
- Fachbereich Luft- und Raumfahrttechnik (141)
- Fachbereich Chemie und Biotechnologie (11)
- Kommission für Forschung und Entwicklung (6)
- Senat (2)
- Arbeitsstelle fuer Hochschuldidaktik und Studienberatung (1)
- Fachbereich Maschinenbau und Mechatronik (1)
Language
- English (674) (remove)
Document Type
- Article (464)
- Conference Proceeding (152)
- Part of a Book (34)
- Book (9)
- Other (4)
- Patent (4)
- Doctoral Thesis (3)
- Lecture (2)
- Conference: Meeting Abstract (1)
- Talk (1)
Keywords
- Finite-Elemente-Methode (12)
- Einspielen <Werkstoff> (10)
- FEM (6)
- Limit analysis (6)
- Shakedown analysis (6)
- shakedown analysis (6)
- Clusterion (5)
- solar sail (5)
- Air purification (4)
- Hämoglobin (4)
- Lipopolysaccharide (4)
- Luftreiniger (4)
- Plasmacluster ion technology (4)
- Raumluft (4)
- Sonde (4)
- limit analysis (4)
- CellDrum (3)
- Einspielanalyse (3)
- Eisschicht (3)
- GOSSAMER-1 (3)
- Kohlenstofffaser (3)
- MASCOT (3)
- Shakedown (3)
- Technische Mechanik (3)
- Traglastanalyse (3)
- lipopolysaccharides (3)
- shakedown (3)
- Analytischer Zulaessigkeitsnachweis (2)
- Biocomposites (2)
- Bruchmechanik (2)
- Einspiel-Analyse (2)
- Erythrozyt (2)
- Fibroblast (2)
- Iterative learning control (2)
- Mars (2)
- Natural fibres (2)
- Pflanzenphysiologie (2)
- Pflanzenscanner (2)
- Polymer-matrix composites (2)
- Solar sail (2)
- Spacecraft (2)
- Stickstoffmonoxid (2)
- Stiffness (2)
- Stress concentrations (2)
- Traglast (2)
- Trajectory Optimization (2)
- bacterial cellulose (2)
- biopotential electrodes (2)
- carbonized rice husk (2)
- celldrum technology (2)
- damage (2)
- limit load (2)
- locomotion (2)
- multiple NEA rendezvous (2)
- muscle fascicle behavior (2)
- nanostructured carbonized plant parts (2)
- nanostrukturierte carbonisierte Pflanzenteile (2)
- nitric oxide gas (2)
- plant scanner (2)
- prebiotic (2)
- ratchetting (2)
- small spacecraft (2)
- ultrasound (2)
- ultrasound imaging (2)
- Achilles tendon (1)
- Adaptive control (1)
- Adsorption (1)
- Ageing (1)
- AlterG (1)
- Alternating plasticity (1)
- Alzheimer's disease (1)
- Analogue Environments (1)
- Analysis (1)
- Anastomose (1)
- Anastomosis (1)
- Anastomotic leakage (1)
- Anatomy (1)
- Annulus Fibrosus (1)
- Antarctic Glaciology (1)
- Antarctica (1)
- Architectural gear ratio (1)
- Assistive technology (1)
- Asteroid Deflection (1)
- Attitude dynamics (1)
- Autofluoreszenzverfahren (1)
- Autolysis (1)
- Automated Optimization (1)
- Automatic control (1)
- Axialbelastung (1)
- Axially cracked pipe (1)
- Bacillus sp (1)
- Bacterial cellulose (1)
- Bakterien (1)
- Basis Reduktion (1)
- Basis reduction (1)
- Bicharakteristikenverfahren (1)
- Biomechanical simulation (1)
- Biomechanics (1)
- Biomechanik (1)
- Biomedizinische Technik (1)
- Bioreaktor (1)
- Biosolubilization (1)
- Bladder (1)
- Blutzellenlagerung (1)
- Bone quality and biomechanics (1)
- Bone sawing (1)
- Carbon sources (1)
- Cardiac myocytes (1)
- Cardiac tissue (1)
- Cell permeability (1)
- Cellular force (1)
- Cellulose nanostructure (1)
- Cement infiltration (1)
- Cementoblast (1)
- Chance constrained programming (1)
- Circular Dichroism (1)
- Coal (1)
- Coefficient of ocular rigidity (1)
- Collagen fibrils (1)
- Compression (1)
- Computational biomechanics (1)
- Connective tissues (1)
- Constitutive model (1)
- Contractile tension (1)
- Convex optimization (1)
- Corneo-scleral shell (1)
- Cost-effectiveness (1)
- Cryobot (1)
- Culture media (1)
- DLR-ESTEC GOSSAMER roadmap for solar sailing (1)
- Damage mechanics theory (1)
- Dattel (1)
- Decomposition (1)
- Deformation (1)
- Dekontamination (1)
- Design-by-analysis (1)
- Differential tonometry (1)
- Disc Degeneration (1)
- Discontinuous fractures (1)
- Druckbeanspruchung (1)
- Druckbehälter (1)
- Druckbelastung (1)
- Druckgeräte (1)
- Drug simulation (1)
- Dry surfaces (1)
- EEG (1)
- ELISA (1)
- ES-FEM (1)
- Einspiel-Kriterium (1)
- Einspielen (1)
- Elastizität (1)
- Elastodynamik (1)
- Elastostatics (1)
- Electromechanical modeling (1)
- Elektrodynamik (1)
- End-to-end colorectal anastomosis (1)
- Endothelial cells (1)
- Endothelial dysfunction (1)
- Endothelzelle (1)
- Environmental impact (1)
- Enzyme-linked immunosorbent assay (1)
- Epithel (1)
- Evolution of damage (1)
- Evolutionary Neurocontrol (1)
- Exact Ilyushin yield surface (1)
- Experiment (1)
- Extension fracture (1)
- Extension strain criterion (1)
- External knee adduction moments (1)
- Extracellular matrix (ECM) (1)
- Extraterrestrial Glaciology (1)
- Eyeball (1)
- FGF23 (1)
- FS-FEM (1)
- Fehlerstellen (1)
- Festkörper (1)
- Finite element analysis (1)
- Finite element analysis (FEA) (1)
- Finite element method (1)
- Finite element modelling (1)
- First Order Reliabiblity Method (1)
- First-order reliability method (1)
- Fließgrenze (1)
- Force (1)
- Forces (1)
- Fracture configuration (1)
- Fracture simulation (1)
- Freeze–thaw process (1)
- Frequency adaption (1)
- Geriatric (1)
- Glaciological instruments and methods (1)
- Glaucoma (1)
- Global and local collapse (1)
- Gossamer (1)
- Gossamer structures (1)
- Grenzwertberechnung (1)
- Growth modelling (1)
- H2 (1)
- Haemodialysis (1)
- Handbike (1)
- Harnleiter (1)
- Heart tissue culture (1)
- Hemoglobin structure (1)
- Hip fractures (1)
- Hodgkin–Huxley models (1)
- Homogenization (1)
- Human-Computer interaction (1)
- Hybrid Propellants (1)
- Hydrodynamik (1)
- Hydrogel (1)
- Hydrogenotrophic methanogens (1)
- Hämoglobinstruktur (1)
- Ice Melting (1)
- Ice melting probe (1)
- Ice penetration (1)
- Icy Moons (1)
- Icy moons (1)
- Impedance Spectroscopy (1)
- Induced pluripotent stem cells (1)
- Inotropic compounds (1)
- Interplanetary flight (1)
- Interstellar objects (1)
- Intervertebral Disc (1)
- Intradiscal Pressure (1)
- Inverse dynamic problem (1)
- Inverse kinematic problem (1)
- Ion channels (1)
- Jupiter (1)
- Kinematics (1)
- Kinetics (1)
- Klotho (1)
- Knee (1)
- Knochen (1)
- Knochenbildung (1)
- Knochenchirugie (1)
- Knochendichte (1)
- Körpertemperatur (1)
- LPS (1)
- Lactobacillus rhamnosus GG (1)
- Lichtstreuungsbasierte Instrumente (1)
- Liver (1)
- Load modeling (1)
- Long COVID (1)
- Low-Thrust Propulsion (1)
- Machine learning (1)
- Manipulated variables (1)
- Materialermüdung (1)
- Mechanical simulation (1)
- Mechanical stability (1)
- Mechanics (1)
- Mechanische Beanspruchung (1)
- Mechanotransduction (1)
- Medusomyces gisevi (1)
- Melting Efficiency (1)
- Melting Performance (1)
- Melting Probe (1)
- Methane (1)
- Methanogenesis (1)
- Microbial adhesion (1)
- Microcirculation (1)
- Mild cognitive impairment (1)
- Missions (1)
- Mohr–Coulomb criterion (1)
- Multi-dimensional wave propagation (1)
- Multimode failure (1)
- Multiphase (1)
- Muscle (1)
- Muscle Fascicle (1)
- Muscle Force (1)
- Muscle fibers (1)
- Musculoskeletal model (1)
- Musculoskeletal system (1)
- Myocardial infarction and cardiac death (1)
- NONOate (1)
- Natriumhypochlorit (1)
- Niacin (1)
- Nichtlineare Gleichung (1)
- Nichtlineare Optimierung (1)
- Nichtlineare Welle (1)
- Nitric Oxide (1)
- Nitric Oxide Donor (1)
- Non-linear optimization (1)
- Non-parallel fissures (1)
- Nucleus Pulposus (1)
- Ocean Worlds (1)
- Ocean worlds (1)
- Ocular blood flow (1)
- Orbital dynamics (1)
- Organkultur (1)
- Osteoporose (1)
- Osteoporosis (1)
- PFM (1)
- PHILAE (1)
- PTH (1)
- Paralympic sport (1)
- Passive stretching (1)
- Pelvic floor dysfunction (1)
- Pelvic muscle (1)
- Permeability (1)
- Permeabilität (1)
- Peroxidase (1)
- Pflanzenstress (1)
- Pharmacology (1)
- Phosphate (1)
- Physiology (1)
- Planetary Protection (1)
- Planetary exploration (1)
- Plastizität (1)
- Post-COVID-19 syndrome (1)
- Pressure loaded crack-face (1)
- Pressure-volume relationship (1)
- Prevention (1)
- Progressive plastic deformation (1)
- Prophylaxis (1)
- Proteine (1)
- Proximal humerus fracture (1)
- Pulsations (1)
- RVA (1)
- Random variable (1)
- Ratcheting (1)
- Ratchetting (1)
- Recombinant activated protein C (1)
- Reconstruction (1)
- Red blood cell storage (1)
- Rehabilitation Technology and Prosthetics (1)
- Rehabilitation engineering (1)
- Reliability analysis (1)
- Reliability of structures (1)
- Retinal vessel analysis (1)
- Retinal vessels (1)
- Reusable Rocket Engines (1)
- Riboflavin (1)
- Robotic rehabilitation (1)
- Rohr (1)
- Rohrbruch (1)
- Rotator cuff (1)
- Running (1)
- S-FEM (1)
- Sampling methods (1)
- Schwammknochen (1)
- Sensitivity (1)
- Sepsis (1)
- Septic cardiomyopathy (1)
- Sequence-Search (1)
- Shakedown criterion (1)
- Simulation (1)
- Skeletal muscle (1)
- Sleep EEG (1)
- Small Aral Sea (1)
- Small Solar System Body Lander (1)
- Small Spacecraft (1)
- Small spacecraft (1)
- Solar Power Sail (1)
- Solar Sail (1)
- Spacecraft Trajectory Optimization (1)
- Spleen (1)
- Stahl (1)
- Statics (1)
- Stochastic programming (1)
- Strukturanalyse (1)
- Subclacial exploration (1)
- Subglacial lakes (1)
- Surface microorganisms (1)
- Surgical Navigation and Robotics (1)
- Surgical staplers (1)
- Swabbing (1)
- Tapered ends (1)
- Temperaturabhängigkeit (1)
- Tendon Rupture (1)
- Tendon properties (1)
- Tendons (1)
- Tension (1)
- Thiamine (1)
- Tissue Engineering (1)
- Training (1)
- Trajectories (1)
- Ultrasound (1)
- Uniaxial compression test (1)
- Ureter (1)
- Variable height stapler design (1)
- Vascular response (1)
- Vasomotions (1)
- Vertebroplastie (1)
- Vertebroplasty (1)
- Viscous flow (1)
- Viskose Strömung (1)
- Viskosität (1)
- Visual field asymmetry (1)
- Vitamin A (1)
- Vitamin B (1)
- Vitamin D (1)
- Wasserbrücke (1)
- Wasserstoffperoxid (1)
- Wellen (1)
- Wolff's Law (1)
- Wolffsches Gesetz (1)
- Wundheilung (1)
- Zug-Druck Belastung (1)
- achilles tendon (1)
- actin cytoskeleton (1)
- activated nanostructured carbon (1)
- adipose-derived stromal cells (ASCs) (1)
- adsorption (1)
- agility (1)
- aktivierte nanostrukturierte Kohlenstofffaser (1)
- alternierend Verformbarkeit (1)
- anaesthetic complications (1)
- anisotropy (1)
- aortic perfusion (1)
- aromatic amines (1)
- asteroid lander (1)
- asteroid sample return (1)
- attitude dynamics (1)
- autofluorescence-based detection system (1)
- biaxial tensile experiment (1)
- bicharacteristics (1)
- biofilms (1)
- biomechanics (1)
- bone density (1)
- bone structure (1)
- burst pressure (1)
- burst tests (1)
- cancellous bone (1)
- cardiomyocyte biomechanics (1)
- cell aerosolization (1)
- cell atomization (1)
- cerebral small vessel disease (1)
- chance constrained programming (1)
- coculture (1)
- cognitive impairment (1)
- community dwelling (1)
- computational fluid dynamics analysis (1)
- connective tissue (1)
- constitutive modeling (1)
- constructive alignment (1)
- contractile tension (1)
- correlation (1)
- crop yield (1)
- cytosolic water diffusion (1)
- date palm tree (1)
- dental trauma (1)
- design-by-analysis (1)
- dialysis (1)
- difficult airway (1)
- direct method (1)
- distorted element (1)
- double-lumen tube intubation (1)
- drop jump (1)
- ecological structure (1)
- elastic solids (1)
- electromyography (1)
- endoluminal (1)
- energy absorption (1)
- energy dissipation (1)
- epithelization (1)
- examination (1)
- exopolysaccharides (1)
- extracorporeal membrane oxygenation (1)
- fatigue analyses (1)
- finite element analysis (1)
- flaw (1)
- flotilla missions (1)
- force generation (1)
- forehead EEG (1)
- fortschreitende plastische Deformation (1)
- gait (1)
- habitability (1)
- healthy aging (1)
- heliosphere (1)
- hemoglobin (1)
- hemoglobin dynamics (1)
- hiPS cardiomyocytes (1)
- high-intensity exercise (1)
- human dermal fibroblasts (1)
- humic acid (1)
- hydrogel (1)
- hyper-gravity (1)
- hyperelastic (1)
- hypo-gravity (1)
- ice moons (1)
- icy moons (1)
- immobilization (1)
- impedance spectroscopy (1)
- in-ear EEG (1)
- intraclass correlation coefficient (1)
- ion propulsion (1)
- kontraktile Spannung (1)
- konvexe Optimierung (1)
- life detection (1)
- light scattering analysis (1)
- lignite (1)
- limit and shakedown analysis (1)
- linear kinematic hardening (1)
- lipopolysaccharide (1)
- load limit (1)
- long-term retention (1)
- low-rank coal (1)
- low-thrust (1)
- low-thrust trajectory optimization (1)
- lower bound theorem (1)
- material shakedown (1)
- mechanical buffer (1)
- mechanical waves (1)
- metagenomics (1)
- microbial diversity (1)
- multimodal (1)
- muscle mechanics (1)
- naphtols (1)
- near-Earth asteroid (1)
- non-simplex S-FEM elements (1)
- nonlinear kinematic hardening (1)
- nonlinear optimization (1)
- nonlinear solids (1)
- nonlinear tensor constitutive equation (1)
- orbit control (1)
- orbital dynamics (1)
- overload (1)
- parabolic flight (1)
- performance testing (1)
- phenols (1)
- physiology (1)
- pipes (1)
- planetary defence (1)
- plant stress (1)
- plasma generated ions (1)
- practical learning (1)
- prevention (1)
- probabilistic fracture mechanics (1)
- protein (1)
- psychosocial (1)
- pullulan (1)
- rehabilitation (1)
- reliability (1)
- reliability analysis (1)
- reliability of structures (1)
- responsive space (1)
- retinal microvasculature (1)
- retinal vessels (1)
- rhAPC (1)
- running (1)
- sEMG (1)
- sailcraft (1)
- sample return (1)
- sarcomere operating length (1)
- second-order reliability method (1)
- sensors (1)
- series elastic element behavior (1)
- shakedown analyses (1)
- shotgun sequencing (1)
- shoulder (1)
- simulation (1)
- small solar system body characterisation (1)
- small spacecraft asteroid lander (1)
- small spacecraft solar sail (1)
- smooth muscle contraction (1)
- soil amendment (1)
- soil health (1)
- soil remediation (1)
- solar sails (1)
- solar system (1)
- space missions (1)
- sprint start (1)
- standard error of measurement (1)
- stiffness (1)
- stochastic programming (1)
- strain energy function (1)
- stretch reflex (1)
- stretch-shortening cycle (1)
- subglacial aquatic ecosystems (1)
- subsurface ice (1)
- subsurface ice research (1)
- subsurface probe (1)
- surface modification (1)
- survival (1)
- system engineering (1)
- tendon rupture (1)
- tension–torsion loading (1)
- test-retest reliability (1)
- thermal ratcheting (1)
- training simulator (1)
- tri-lineage differentiation (1)
- twin-fluid atomizer (1)
- ultrasonography (1)
- underwater vehicle (1)
- unloading (1)
- vessels (1)
- videolaryngoscopy (1)
- virgin passive (1)
- virtual reality (1)
- viscoelasticity (1)
- walking (1)
- walking gait (1)
- water bridge phenomenon (1)
- wound healing (1)
- yield stress (1)
A generalized shear-lag theory for fibres with variable radius is developed to analyse elastic fibre/matrix stress transfer. The theory accounts for the reinforcement of biological composites, such as soft tissue and bone tissue, as well as for the reinforcement of technical composite materials, such as fibre-reinforced polymers (FRP). The original shear-lag theory proposed by Cox in 1952 is generalized for fibres with variable radius and with symmetric and asymmetric ends. Analytical solutions are derived for the distribution of axial and interfacial shear stress in cylindrical and elliptical fibres, as well as conical and paraboloidal fibres with asymmetric ends. Additionally, the distribution of axial and interfacial shear stress for conical and paraboloidal fibres with symmetric ends are numerically predicted. The results are compared with solutions from axisymmetric finite element models. A parameter study is performed, to investigate the suitability of alternative fibre geometries for use in FRP.
Virgin passive colon biomechanics and a literature review of active contraction constitutive models
(2022)
The objective of this paper is to present our findings on the biomechanical aspects of the virgin passive anisotropic hyperelasticity of the porcine colon based on equibiaxial tensile experiments. Firstly, the characterization of the intestine tissues is discussed for a nearly incompressible hyperelastic fiber-reinforced Holzapfel–Gasser–Ogden constitutive model in virgin passive loading conditions. The stability of the evaluated material parameters is checked for the polyconvexity of the adopted strain energy function using positive eigenvalue constraints of the Hessian matrix with MATLAB. The constitutive material description of the intestine with two collagen fibers in the submucosal and muscular layer each has been implemented in the FORTRAN platform of the commercial finite element software LS-DYNA, and two equibiaxial tensile simulations are presented to validate the results with the optical strain images obtained from the experiments. Furthermore, this paper also reviews the existing models of the active smooth muscle cells, but these models have not been computationally studied here. The review part shows that the constitutive models originally developed for the active contraction of skeletal muscle based on Hill’s three-element model, Murphy’s four-state cross-bridge chemical kinetic model and Huxley’s sliding-filament hypothesis, which are mainly used for arteries, are appropriate for numerical contraction numerical analysis of the large intestine.
Three-dimensional (3D) full-field measurements provide a comprehensive and accurate validation of finite element (FE) models. For the validation, the result of the model and measurements are compared based on two respective point-sets and this requires the point-sets to be registered in one coordinate system. Point-set registration is a non-convex optimization problem that has widely been solved by the ordinary iterative closest point algorithm. However, this approach necessitates a good initialization without which it easily returns a local optimum, i.e. an erroneous registration. The globally optimal iterative closest point (Go-ICP) algorithm has overcome this drawback and forms the basis for the presented open-source tool that can be used for the validation of FE models using 3D full-field measurements. The capability of the tool is demonstrated using an application example from the field of biomechanics. Methodological problems that arise in real-world data and the respective implemented solution approaches are discussed.
Electromechanical model of hiPSC-derived ventricular cardiomyocytes cocultured with fibroblasts
(2018)
The CellDrum provides an experimental setup to study the mechanical effects of fibroblasts co-cultured with hiPSC-derived ventricular cardiomyocytes. Multi-scale computational models based on the Finite Element Method are developed. Coupled electrical cardiomyocyte-fibroblast models (cell level) are embedded into reaction-diffusion equations (tissue level) which compute the propagation of the action potential in the cardiac tissue. Electromechanical coupling is realised by an excitation-contraction model (cell level) and the active stress arising during contraction is added to the passive stress in the force balance, which determines the tissue displacement (tissue level). Tissue parameters in the model can be identified experimentally to the specific sample.
The overall objective of this study is to develop a new external fixator, which closely maps the native kinematics of the elbow to decrease the joint force resulting in reduced rehabilitation time and pain. An experimental setup was designed to determine the native kinematics of the elbow during flexion of cadaveric arms. As a preliminary study, data from literature was used to modify a published biomechanical model for the calculation of the joint and muscle forces. They were compared to the original model and the effect of the kinematic refinement was evaluated. Furthermore, the obtained muscle forces were determined in order to apply them in the experimental setup. The joint forces in the modified model differed slightly from the forces in the original model. The muscle force curves changed particularly for small flexion angles but their magnitude for larger angles was consistent.
Surgical reconstruction of the interosseous membrane (IOM) could restore longitudinal forearm stability to avoid persisting disability due to capituloradial and ulnocarpal impingement in Essex Lopresti lesions. This biomechanical study aimed to assess longitudinal forearm stability of intact specimens, after sectioning of the IOM and after reconstruction with a TightRope construct using either a single or double bundle technique.
Pelvic floor dysfunction (PFD) is characterized by the failure of the levator ani (LA) muscle to maintain the pelvic hiatus, resulting in the descent of the pelvic organs below the pubococcygeal line. This chapter adopts the modified Humphrey material model to consider the effect of the muscle fiber on passive stretching of the LA muscle. The deformation of the LA muscle subjected to intra-abdominal pressure during Valsalva maneuver is compared with the magnetic resonance imaging (MRI) examination of a nulliparous female. Numerical result shows that the fiber-based Humphrey model simulates the muscle behavior better than isotropic constitutive models. Greater posterior movement of the LA muscle widens the levator hiatus due to lack of support from the anococcygeal ligament and the perineal structure as a consequence of birth-related injury and aging. Old and multiparous females with uncontrolled urogenital and rectal hiatus tend to develop PFDs such as prolapse and incontinence.
While plate fixation of proximal ulna fractures might lead to superior clinical results compared to tension band wiring, regular plates represent an established risk factor for wound complications. The olecranon double plates (Medartis, Basel, CH) might decrease complications related to the osteosynthesis because of their low profile and better anatomical fit. This study aimed to evaluate the biomechanical performance and clinical results of the olecranon double plates.
FEM shakedown analysis of structures under random strength with chance constrained programming
(2022)
Direct methods, comprising limit and shakedown analysis, are a branch of computational mechanics. They play a significant role in mechanical and civil engineering design. The concept of direct methods aims to determine the ultimate load carrying capacity of structures beyond the elastic range. In practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and constraints. If strength and loading are random quantities, the shakedown analysis can be formulated as stochastic programming problem. In this paper, a method called chance constrained programming is presented, which is an effective method of stochastic programming to solve shakedown analysis problems under random conditions of strength. In this study, the loading is deterministic, and the strength is a normally or lognormally distributed variable.
For pelvic floor disorders that cannot be treated with non-surgical procedures, minimally invasive surgery has become a more frequent and safer repair procedure. More than 20 million prosthetic meshes are implanted each year worldwide. The simple selection of a single synthetic mesh construction for any level and type of pelvic floor dysfunctions without adopting the design to specific requirements increase the risks for mesh related complications. Adverse events are closely related to chronic foreign body reaction, with enhanced formation of scar tissue around the surgical meshes, manifested as pain, mesh erosion in adjacent structures (with organ tissue cut), mesh shrinkage, mesh rejection and eventually recurrence. Such events, especially scar formation depend on effective porosity of the mesh, which decreases discontinuously at a critical stretch when pore areas decrease making the surgical reconstruction ineffective that further augments the re-operation costs. The extent of fibrotic reaction is increased with higher amount of foreign body material, larger surface, small pore size or with inadequate textile elasticity. Standardized studies of different meshes are essential to evaluate influencing factors for the failure and success of the reconstruction. Measurements of elasticity and tensile strength have to consider the mesh anisotropy as result of the textile structure. An appropriate mesh then should show some integration with limited scar reaction and preserved pores that are filled with local fat tissue. This chapter reviews various tissue reactions to different monofilament mesh implants that are used for incontinence and hernia repairs and study their mechanical behavior. This helps to predict the functional and biological outcomes after tissue reinforcement with meshes and permits further optimization of the meshes for the specific indications to improve the success of the surgical treatment.
Shakedown analysis of two dimensional structures by an edge-based smoothed finite element method
(2010)
We propose the so-called chance constrained programming model of stochastic programming theory to analyze limit and shakedown loads of structures under random strength with a lognormal distribution. A dual chance constrained programming algorithm is developed to calculate simultaneously both the upper and lower bounds of the plastic collapse limit and the shakedown limit. The edge-based smoothed finite element method (ES-FEM) is used with three-node linear triangular elements.
Analysis of the long-term effect of the MBST® nuclear magnetic resonance therapy on gonarthrosis
(2016)
The structure of the female pelvic floor (PF) is an inter-related system of bony pelvis,muscles, pelvic organs, fascias, ligaments, and nerves with multiple functions. Mechanically, thepelvic organ support system are of two types: (I) supporting system of the levator ani (LA) muscle,and (II) the suspension system of the endopelvic fascia condensation [1], [2]. Significantdenervation injury to the pelvic musculature, depolimerization of the collagen fibrils of the softvaginal hammock, cervical ring and ligaments during pregnancy and vaginal delivery weakens thenormal functions of the pelvic floor. Pelvic organ prolapse, incontinence, sexual dysfunction aresome of the dysfunctions which increases progressively with age and menopause due toweakened support system according to the Integral theory [3]. An improved 3D finite elementmodel of the female pelvic floor as shown in Fig. 1 is constructed that: (I) considers the realisticsupport of the organs to the pelvic side walls, (II) employs the improvement of our previous FEmodel [4], [5] along with the patient based geometries, (III) incorporates the realistic anatomy andboundary conditions of the endopelvic (pubocervical and rectovaginal) fascia, and (IV) considersvarying stiffness of the endopelvic fascia in the craniocaudal direction [3]. Several computationsare carried out on the presented computational model with healthy and damaged supportingtissues, and comparisons are made to understand the physiopathology of the female PF disorders.
The human arm consists of the humerus (upper arm), the medial ulna and the lateral radius (forearm). The joint between the humerus and the ulna is called humeroulnar joint and the joint between the humerus and the radius is called humeroradial joint. Lateral and medial collateral ligaments stabilize the elbow. Statistically, 2.5 out of 10,000 people suffer from radial head fractures [1]. In these fractures the cartilage is often affected. Caused by the injured cartilage, degenerative diseases like posttraumatic arthrosis may occur. The resulting pain and reduced range of motion have an impact on the patient’s quality of life. Until now, there has not been a treatment which allows typical loads in daily life activities and offers good long-term results. A new surgical approach was developed with the motivation to reduce the progress of the posttraumatic arthrosis. Here, the radius is shortened by 3 mm in the proximal part [2]. By this means, the load of the radius is intended to be reduced due to a load shift to the ulna. Since the radius is the most important stabilizer of the elbow it has to be confirmed that the stability is not affected. In the first test (Fig. 1 left), pressure distributions within the humeroulnar and humeroradial joints a native and a shortened radius were measured using resistive pressure sensors (I5076 and I5027, Tekscan, USA). The humerus was loaded axially in a tension testing machine (Z010, Zwick Roell, Germany) in 50 N steps up to 400 N. From the humerus the load is transmitted through both the radius and the ulna into the hand which is fixed on the ground. In the second test (Fig. 1 right), the joint stability was investigated using a digital image correlation system to measure the displacement of the ulna. Here, the humerus is fixed with a desired flexion angle and the unconstrained forearm lies on the ground. A rope connects the load actuator with a hook fixed in the ulna. A guide roller is used so that the rope pulls the ulna horizontally when a tensile load is applied. This creates a moment about the elbow joint with a maximum value of 7.5 Nm. Measurements were performed with varying flexion angles (0°, 30°, 60°, 90°, 120°). For both tests and each measurement, seven specimens were used. Student ́s t-test was employed to determine whether the mean values of the measurements in native specimen and operated specimens differ significantly.
Human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CM) today are widely used for the investigation of normal electromechanical cardiac function, of cardiac medication and of mutations. Computational models are thus established that simulate the behavior of this kind of cells. This section first motivates the modeling of hiPS-CM and then presents and discusses several modeling approaches of microscopic and macroscopic constituents of human-induced pluripotent stem cell-derived and mature human cardiac tissue. The focus is led on the mapping of the computational results one can achieve with these models onto mature human cardiomyocyte models, the latter being the real matter of interest. Model adaptivity is the key feature that is discussed because it opens the way for modeling various biological effects like biological variability, medication, mutation and phenotypical expression. We compare the computational with experimental results with respect to normal cardiac function and with respect to inotropic and chronotropic drug effects. The section closes with a discussion on the status quo of the specificity of computational models and on what challenges have to be solved to reach patient-specificity.
Effectiveness of the edge-based smoothed finite element method applied to soft biological tissues
(2012)
Smoothed Finite Element Methods for Nonlinear Solid Mechanics Problems: 2D and 3D Case Studies
(2016)
The Smoothed Finite Element Method (SFEM) is presented as an edge-based and a facebased techniques for 2D and 3D boundary value problems, respectively. SFEMs avoid shortcomings of the standard Finite Element Method (FEM) with lower order elements such as overly stiff behavior, poor stress solution, and locking effects. Based on the idea of averaging spatially the standard strain field of the FEM over so-called smoothing domains SFEM calculates the stiffness matrix for the same number of degrees of freedom (DOFs) as those of the FEM. However, the SFEMs significantly improve accuracy and convergence even for distorted meshes and/or nearly incompressible materials.
Numerical results of the SFEMs for a cardiac tissue membrane (thin plate inflation) and an artery (tension of 3D tube) show clearly their advantageous properties in improving accuracy particularly for the distorted meshes and avoiding shear locking effects.
Postural and metabolic benefits of using a forearm support walker in older adults with impairments
(2019)
Influence of refrigerated storage on tensile mechanical properties of porcine liver and spleen
(2015)
Sensitivity of and Influences on the Reliability of an HTR-Module Primary Circuit Pressure Boundary
(1993)
Plate osteosynthesis of displaced proximal phalangeal neck fractures of the hand allows early mobilization due to a stable internal fixation. Nevertheless, joint stiffness—because of soft tissue irritation—represents a common complication leading to high complication rates. Del Pinal et al. recently reported promising clinical results for a new, minimally invasive fixation technique with a cannulated headless intramedullary compression screw. Hence, the aim of this study was to compare plate fixation of proximal phalangeal neck fractures to less two less invasive techniques: Crossed k-wire fixation and intramedullary screw fixation. We hypothesized that these fixation techniques provide inferior stability when compared to plate osteosynthesis.
A new in vitro tool to investigate cardiac contractility under physiological mechanical conditions
(2019)
Abstracts of the ACHEMA 2000 - International Meeting on Chemical Engineering, Environmental Protection and Biotechnology, May 22 - 27, 2000. Frankfurt am Main. Achema 2000 : special edition / Linde. [Ed.: Linde AG. Red.: Volker R. Leski]. - Wiesbaden : Linde AG, 2000. - 56 p. : Ill., . - pp: 79 - 81