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Adult distal humerus fractures are infrequent, yet they account for one-third of all humerus fractures. For the treatment of comminuted and osteoporotic fractures, locking plates are claimed to be biomechanically superior to alternative internal fixing techniques. Treatment remains difficult despite recent advancements and the use of locking plates due to frequent comminution, low bone quality, and limited healing ability in osteoporotic bone. An optimal design of the newly constructed plate and the control model were selected. The biomechanical characteristics of non-osteoporotic and osteoporotic synthetic bone were compared on six models. The biomechanical properties of the new plate were tested and compared on 54 osteoporotic synthetic humerus models. The control models were reconstructive and parallel LCPs. The tests were carried out under static and dynamic axial, lateral and bending loads. Fracture displacements were measured by optical measuring system Aramis. The test model is significantly stiffer for lateral load (p = 0.0007) and for bending load at the moment of model failure (p = 0.0002), while for axial load the LCP model showed greater stiffness (p = 0.0017). During lateral dynamic loading, all three LCP models broke and there was a significant difference compared to the test model (p = 0.0125). The LCP model is dynamically significantly more durable under axial load, while the largest displacements were recorded with the test model (p = 0.029). The displacements induced by all three loads are within the limits that fulfil the parameters of appropriate biomechanical stability. A novel locking plate for extra- articular distal humerus fractures may provide an alternative to the traditional two-plate.

The price of material is an important factor when selecting the additive polymer procedure. In selective laser sintering (SLS), the price can be reduced by the recycling of material, i.e., with different shares of original and recycled material, as well as by the orientation of the product during manufacturing. Numerous tests warn that orientation in the direction of z axis should be as low as possible to reduce the total price of the product. The product also has to satisfy the influence of atmospheric conditions to which it is exposed during its lifetime, i.e., UV radiation and humid environment. UV light, with sun being its most common source, and average humidity in different parts of the world can be approximately from 20% to 90%, depending on time, day and geographic location. In this work, the test specimens have been made of original, mixed and 100% recycled material and then exposed to the influences of UV radiation and water absorption. After having been exposed to atmospheric conditions for a longer time, the mechanical properties of the polyamide products made by selective laser sintering were tested. The results show that exposure to UV radiation reduces tensile elongation at all ratios of recycled material and orientation of 70–90% except in the z direction, while in flexural deformation it is the other way around. The effect of water was observed only between the 7th–14th day of absorption with a decrease in strength until the deformation did not change.

International audience; In this paper the nonlinear behavior of nodular graphite cast iron is investigated under in-plane biaxial loading regimes. Multiaxial experiments enable a wide variety of loading paths to be investigated. In the presented study two loading histories are proposed, namely, equibiaxial and " snail " loading paths corresponding to proportional and nonproportional regimes. The center gauge zone of the testing cruciform specimen is observed. Mean strain fluctuations are measured and presented in order to determine the material response for the prescribed biaxial loading paths. For the equibiaxial and snail loading histories finite element model updating will couple 2D-DIC measurements with 3D-FE analyses to calibrate material parameters describing elasticity, isotropic or kinematic hardening.

This paper investigates the behaviour of a receding contact when a cylindrical indenter presses an unbonded layer resting on a substrate. The problem is analysed by using FEM within the scope of the linear theory of elasticity and under the assumption of plane strain. This paper presents new and original results in the analysis of influence of load intensity and indenter geometry on the contact parameters. In addition, in the investigation into material properties a reference analysis was carried out for the case of material similarity between all three bodies, and material properties were subsequently varied for each body. This class of problems shows nonlinear behaviour, with both contact pressure distributions and contact half-widths found to depend nonlinearly on the applied load. The experimental analysis was carried out by employing the digital image correlation method and the ARAMIS 4M system was used. The obtained measurement results show good agreement with the numerical results.

Through many stages of development, from conservative to operative treatment, open reduction and internal fixation with dual plating systems are the golden standard for fixation of distal humerus fractures. The plates are placed with a slight offset, posteromedially and posterolaterally. In recent publications, a higher stiffness and strength of osteosynthesis in the parallel plating technique were compared to the perpendicular technique with different plate designs. As noted in previous studies, non-union of the distal humerus usually occurs in the region at the metaphyseal and supracondylar level of radial columns due to varus stresses. Therefore the hypothesis is that in the case of extraarticular methphyseal fractures, which are treated with two plates perpendicular or parallel to form, the radial side of the plate should be longer than the ulnar side in order to prevent varus stresses as the main cause of the distal humeral pseudoarthrosis. Sufficient stability can be ensured with newly designed Y-shaped plate which should have a longer radial arm and be configured to prevent varus stresses. To prove this hypothesis, biomechanical studies at the supracondylar metaphyseal level on the border of the distal humerus diaphysis should be performed., U razvojnom procesu od konzervativnog pa do operativnog liječenja prijeloma distalnog humerusa, otvorena repozicija te unutrašnja fiksacija pločicama i vijcima su se pokazale kao najbolja metoda liječenja. Pločice se postavljaju uz blagi pomak posteromedijalno i posterolateralno. U posljednjim biomehaničkim studijama uglavnom je analizirana i uspoređivana krutost i stabilnost osteosinteze s različitim pločicama u paralelnoj i perpendikularnoj konfiguraciji. Dosadašnja istraživanja su također pokazala da su loši rezultati liječenja prijeloma distalnog humerusa uglavnom posljedica neadekvatnog cijeljenja u metafizarnoj i suprakondilarnoj regiji radijalne kolumne zbog varusnih naprezanja. Stoga je hipoteza rada da kod ekstraartikularnih metafizarnih prijeloma koji se liječe s dvije pločice u paralelnoj ili perpendikularnoj konfiguraciji, pločica na radijalnoj strani treba biti dulja od ulnarne kako bi se izbjegla varusna naprezanja koja su u većini slučajeva glavni uzročnik pojave pseudoartroze distalnog humerusa. Dovoljna stabilnost koštanih ulomaka može se osigurati novodizajniranom Y pločicom koja je konfigurirana na način da ima dulji radijalni krak, čime se znatno smanjuju varusna naprezanja. Da bi se navedena hipoteza dokazala, potrebno je provesti biomehanička istraživanja u suprakondilarnoj i metafizarnoj regiji na prijelazu u dijafizarnu regiju distalnog humerusa.

To investigate the applicability of infrared thermography as a tool for acquiring dynamic yielding in metals, a comparison of infrared thermography with three dimensional digital image correlation has been made. Dynamical tension tests and three point bending tests of aluminum alloys have been performed to evaluate results obtained by IR thermography in order to detect capabilities and limits for these two methods. Both approaches detect pastification zone migrations during the yielding process. The results of the tension test and three point bending test proved the validity of the IR approach as a method for evaluating the dynamic yielding process when used on complex structures such as cellular porous materials. The stability of the yielding process in the three point bending test, as contrary to the fluctuation of the plastification front in the tension test, is of great importance for the validation of numerical constitutive models. The research proved strong performance, robustness and reliability of the IR approach when used to evaluate yielding during dynamic loading processes, while the 3D DIC method proved to be superior in the low velocity loading regimes. This research based on two basic tests, proved the conclusions and suggestions presented in our previous research on porous materials where middle wave infrared thermography was applied.

Tensile strength tests are performed on small scale corroded specimens, so as to derive their mechanical properties. The specimens were cut from a box girder that was initially corroded in real sea water conditions. As a result of the tensile tests the mechanical properties of the specimens are determined, namely modulus of elasticity, yield stress, tensile strength, resilience, fracture toughness and total uniform elongation. Regression equations are derived for the properties as a function of the degree of corrosion degradation. It is identified that those material parameters are influenced by the severity of corrosion degradation.

The present paper evaluates the fatigue life of ductile nodular cast iron EN-GJS-400-18LT with four different microstructures. Characterisation of the graphite morphology and the matrix microstructure is performed on 50 samples for every material type. Tensile stress–strain curves, symmetrical and unsymmetrical stress–strain hysteresis loops, cyclic stress–strain curves, crack resistance curves and fatigue life curves of these four microstructures are obtained. Experimental results show that size, shape and distribution of the graphite nodules has no significant influence on cyclic hardening of the material but they play a great role in the crack initiation and propagation process. It is shown that the larger irregularly shaped nodules reduce fracture toughness and fatigue strength. Furthermore, the results demonstrated that pearlitic phase does not strongly affect fatigue life if its proportion does not exceed 10%. The monitoring of crack length during the tests is performed by an optical method developed in the present work.

This report firstly presents the rule based scantlings and sectional properties of the example ship defined by using the nominal properties of mild shipbuilding steel. It also describes the way of collection of characteristic material specimens of rolled steel plates and bars delivered by the steel manufacturer to the shipyard for to the example ship. Secondly it summarizes the results of tensile testing in the Laboratory for experimental mechanics of the Faculty of Mechanical Engineering and Naval Architecture in Zagreb of plates and bars denoted here as ‘in-built’ material properties for the example ship according to the production plans. The report then reminds on the rule based material properties for acceptance purposes. Next it considers the influence of ‘in-built’ mechanical properties with respect to the rule requirements on local, global and ultimate strength of ships. The report discusses material properties other than yield strength, which participate in the assessment of the overall ship safety such as the weld strength, buckling and fatigue strength, low temperature behavior, corrosion and reliability. The results of the tensile testing of ‘in-built’ materials are then applied to checking of the local, global and ultimate ‘as-built’ strength of the example ship’s hull instead of the ‘as-designed’ strength defined by the nominal material properties. The report at the end discusses the differences between the ‘as-designed’ and the ‘as-built’ hull strength, fatigue life and reliability. It suggests minimization of the hull strength uncertainties by adopting the mechanical properties of ‘inbuilt’ materials. The conclusion supports the stirring idea of this report that in addition to the ‘as-designed’ strength, a ship deserves individualized assessment of the “as-built” ship hull strength based on the measured realistic ‘in-built’ properties.

This paper presents an experimental and numerical study on two different types of the nodular cast iron EN-GJS-400-18-LT. The experimental procedure includes symmetrical and unsymmetrical strain controlled tests on the cylindrical specimens as well as crack initiation and propagation tests on the compact tension and single edged notched specimens. Different loading regimes are applied, and monitoring of the crack length during the tests is performed by an optical system. Within the framework of numerical investigations an efficient algorithm for modelling of cyclic plasticity is examined. Experimental results show that two material types have significantly different the crack behaviour.

Background and Purpose: Human walking has been extensively studied by many investigators and numerous mathematical models of lower limb movements have been developed but few reports have been written about contribution of the upper limbs to the locomotion process. The aim of this study was to investigate the influence of walking speed and effect of the upper limb swing on the trajectory of the whole body mass center, as well as on ground reaction forces during human walking. Material and Methods: An automatized method for determination of the whole body mass center has been established. Gait analysis was performed on 52 subjects using the Elite system and Kistler force platform. The recording of trajectories of characteristic body points on subjects and measurement of ground reaction forces were performed at normal speed walking with natural and emphasized rhythmic upper limb swing and at fast walking speed. The determined mean values of normalized components of trajectory of the body mass center and ground reaction forces were compared. Result and Conclusion: The study showed that components of ground reaction forces and trajectory of the whole body center of mass are influenced by changes in arm swing and gait velocity. Maximum magnitudes of components of ground reaction force increased for normal speed walking with emphasized upper limb swing. The emphasized upper limb swing decreased the magnitude of vertical oscillations of the body center of mass and thus may influence energy expenditure.

The aim of this study was to investigate the influence of the upper limb swing on human gait. Measurements were performed on 52 subjects by using the Elite system with two cameras and a Kistler force platform. The recording of trajectories of characteristic body points on the subjects and the measurement of ground reaction forces have been performed at normal walking and at walking with emphasised rhythmic upper limb swing. The trajectory of the whole body mass centre, central dynamic moments of inertia and ground reaction forces have been calculated for every subject and mean curves of the entire group have been determined for walking with the natural and the emphasised upper limb swing. The determined mean values of normalised mechanical parameters have been compared and differences between the gait with the natural and the emphasised upper limb swing have been described.

The effects of smoothing non-smooth function on estimation of dynamical stability of the periodic response determined in the frequency domain are considered in this paper. For that purpose, a simple single-degree-of-freedom system with piecewise-linear force-displacement relationship subjected to a harmonic force excitation is analyzed. Stability of the periodic response obtained in the frequency domain by the incremental harmonic balance method is determined by using the Floquet-Liapounov theorem. Results obtained are verified in the time domain by the method of piecing the exact solutions and Runge-Kutta integration routine.