The aim of this paper is to review the evidence relating to the anatomy of the proximal femur, the geometry of the fracture and the characteristics of implants and methods of fixation of ...intertrochanteric fractures of the hip.
Relevant papers were identified from appropriate clinical databases and a narrative review was undertaken.
Stable, unstable, and subtrochanteric intertrochanteric fractures vary widely in their anatomical and biomechanical characteristics, as do the implants used for their fixation. The optimal choice of implant addresses the stability of the fracture and affects the outcome.
The treatment of intertrochanteric fractures of the hip has evolved along with changes in the design of the implants used to fix them, but there remains conflicting evidence to guide the choice of implant. We advocate fixation of 31A1 fractures with a sliding hip screw and all others with an intramedullary device. Cite this article: Bone Joint J 2017;99-B:128-33.
The isogeometric method is used to study the free vibration of thick plates based on Mindlin theory. The Non-uniform Rational B-Spline (NURBS) basis functions are employed to build the thick plate’s ...geometry models and serve as the shape functions for solution field approximation in finite element analysis. The Reissner–Mindlin plates built with multiple NURBS patches are investigated, in which several patches of the model have multi-interface and different patches may share a common point. In order to solve the non-conforming interface problems, Nitsche method is employed to glue different NURBS patches and only refers to the coupling conditions in this work. Various plate shapes, different boundary conditions and several kinds of thickness-span ratios are considered to verify the validity of the presented method. The dimensionless frequencies for different cases are obtained by solving the eigenvalue equation problems and compared with the existing reference solutions or the results calculated by ABAQUS software. Several numerical examples exhibit the effectiveness of the isogeometric approach. It shows that the natural frequencies of the Reissner–Mindlin plate can be successfully predicted by the combination of isogeometric analysis and Nitsche method.
•Isogeometric method for free vibration of non-conforming Mindlin plate is proposed.•Cases of multi-interface and multi-patches sharing one common point are considered.•The mode frequencies of non-conforming Mindlin plate could be predicted.•Nitsche based isogeometric method can provide approving convergence.
•A new type earthquake-resilient PSCWJ is put forward.•The mechanics mechanism and seismic design requirements of PSCWJ are introduced.•The design theory of an earthquake-resilient PSCWJ is ...established.•The rationality of the design theory of PSCWJ proposed in this study is verified.•PSCWJ has good bearing behaviour, ductility, and earthquake resilience capacity.
Prefabricated steel structure systems have become a new trend in the development of steel structures. In particular, earthquake-resilient steel structures have become a hot issue in the field of structural seismic research. Based on the idea of damage control and a new kind of energy-saving, material-saving and environmentally friendly sinusoidal corrugated web, this paper put forward a new type of earthquake-resilient prefabricated sinusoidal corrugated web beam-column joint (PSCWJ). Then, its constitution, its mechanics mechanism and its seismic design requirements are introduced. After considering the influence of the bolt binding coefficient, the overall bending of the binding section and the overall instability of the flange cover plate, the design theory of the earthquake-resilient PSCWJ is established. Through 55 examples of PSCWJs, the rationality of the design theory proposed in this study is verified, and a reasonable value range of the middle bolt interval on the flange cover plate is determined. During the process of theoretical derivation, the influences of many design parameters are considered, such as the section parameters of the sinusoidal corrugated web beam and cantilever beam, the thickness of the flange cover plate, the material properties of the flange cover plate, the diameter of bolts, the middle bolt interval and the weaken rate of the cover plate. Research shows that the design theory proposed in this paper can predict the yield load of PSCWJ accurately and effectively control the ultimate bearing capacity of PSCWJ. The PSCWJ designed through this theory has good bearing behaviour and ductility, which can make sure the main members, such as the beam and the column, remain in an elastic range and meet the requirements of earthquake resilience.
•A Rayleigh-Ritz approach for post-buckling analysis of variable angle tow composites is proposed.•Stiffened panels are modelled by a domain decomposition method and penalty techniques.•General ...symmetric and non-symmetric lay-ups can be investigated.•Post-buckling regime for variable angle tow stiffened composite plates is addressed for the first time.•The obtained results show the applicability and effectiveness of the approach.
A Rayleigh-Ritz solution approach for generally restrained multilayered variable angle tow stiffened plates in postbuckling regime is presented. The plate model is based on the first order shear deformation theory and accounts for geometrical nonlinearity through the von Kármán’s assumptions. Stiffened plates are modelled as assembly of plate-like elements and penalty techniques are used to join the elements in the assembled structure and to apply the kinematical boundary conditions. General symmetric and unsymmetric stacking sequences are considered and Legendre orthogonal polynomials are employed to build the trial functions. A computer code was developed to implement the proposed approach and to establish its applicability and its features for investigating variable angle tow structures. The proposed solution is validated by comparison with literature and finite elements results. Original results are presented for postbuckling of variable angle tow stiffened plates showing the potentialities of the method.
Initiation of Mariana-type oceanic subduction zones requires rheologically strong oceanic lithosphere, which developed through secular cooling of Earth's mantle. Here, we report a 518 Ma Mariana-type ...subduction initiation ophiolite from northern Tibet, which, along with compilation of similar ophiolites through Earth history, argues for the establishment of the modern plate tectonic regime by the early Cambrian. The ophiolite was formed during the subduction initiation of the Proto-Tethys Ocean that coincided with slab roll-back along the southern and western Gondwana margins at ca. 530-520 Ma. This global tectonic re-organization and the establishment of modern plate tectonic regime was likely controlled by secular cooling of the Earth, and facilitated by enhanced lubrication of subduction zones by sediments derived from widespread surface erosion of the extensive mountain ranges formed during Gondwana assembly. This time also corresponds to extreme events recorded in climate and surface proxies that herald formation of the contemporary Earth.
•Aim of the present study: identification of equivalent viscoelastic models for layered thin walled structures, obtained from vibration measurement only, able to fit the experimental data on a ...relatively wide frequency range by means of a minimum number of parameters.•Circle-fit technique: the classical circle-fit technique is extended to include the possibility of identifying the damping properties of vibrating structures by means of non-conventional viscoelastic models, like fractional derivative models.•Fractional derivative rheological models: the Fractional Kelvin model is adopted for identifying the parameters of a complex Young’s modulus in the frequency domain, modelling the viscoelastic properties of a homogenized structure.•Experimental results: analysis of vibrating plates made of Quiet Aluminum (QA) and of vibrating Aluminum plates coated by damping pads (ADP), assessing the accuracy of the identified parameters by comparison of numerically simulated with experimentally measured FRFs.
Aim of the present study is the identification of equivalent viscoelastic models for layered thin walled structures, obtained from vibration measurement only, able to fit the experimental data on a relatively wide frequency range by means of a minimum number of parameters. A novel approach is proposed, based on a definition of an equivalent modal damping ratio applied to the circle-fit technique, to overcome the difficulties related to the identification of modal parameters when adopting non-conventional viscoelastic models. When the structural internal dissipative effects are dominant, this procedure identifies the parameters of an equivalent Young’s modulus in the frequency domain, representing the viscoelastic properties of a homogenized structure as a scalar function with frequency-dependent real and imaginary parts. The proposed procedure is applied to the analysis of Aluminum plates coated by damping pads and of plates made by Quiet Aluminum. To fit the experimentally found equivalent modal damping ratios, several viscoelastic models are adopted and compared (viscous, hysteretic, generalized Maxwell, fractional derivative damping, and in particular the Fractional Kelvin-Voigt model), assessing the accuracy of the identified parameters by comparison of numerically simulated with experimentally measured frequency response functions.
In this paper a composite fractional fractal zone plate (CFFZP) based on the corresponding fractional fractal zone plate is proposed to enhance the intensity of the arbitrarily designed main focus. ...The construction method of the CFFZP has been illustrated in the simulation. It has been also proved in the simulations and experiments that the CFFZP generates the main focus with higher intensity. The proposed zone plate can be applied to stably trap a particle at an arbitrary plane and generate a clearer image at an arbitrary axial position.
Hot embossing is a low‐cost and flexible method for fabricating microstructures and nanostructures on polymers. However, the conventional hot embossing process poses two challenges: First, the plates ...that are used do not provide uniform pressure, and the size of the chamber limits the imprinting area. Second, heating with thick metal plates significantly lengthens cycle time. Finally, the uniformity of temperature also affects the embossing results. To achieve a high heating rate and uniform pressure over a large area, this study combined an induction heating system and roll‐to‐plate hot embossing. A movable plate was used to move the mold through the induction coil, increasing the heating area and overcoming limitations related to the embossing area posed by the coil length. The imprinting area reached 100 × 100 mm2. In addition, the temperature difference was less than 20°C at each molding temperature range from 150°C to 190°C. The mold and the substrate were placed on a vacuum absorber to prevent deformation and slippage of the mold and provide preloading and packing pressure. Cooling fans were employed to improve cooling efficiency. Experimental replication yielded replication rates higher than 97% at 190°C and 5 kgf/cm2 with a cycle time of approximately 2 minutes. To verify the feasibility of the process, V‐groove microstructures were successfully fabricated using a movable induction heating roller embossing facility.
Highlights
The feasibility of the moving induction heating roller embossing process.
A vacuum movable platform prevents deformation and slippage of the substrate.
Improve the temperature uniformity of the movable platform.
This experiment used a magnetic concentrator and multi‐stage power control to improve the temperature uniformity of a mobile vacuum imprinting platform. The feasibility of large‐area imprinting was achieved.
The free vibration of simply supported functionally graded rectangular plates resting on two-parameter elastic foundation is studied using the higher-order shear and normal deformable plate theory of ...Batra and Vidoli by an analytical approach. All three displacement components are expanded in the thickness direction using the Legendre polynomials. The effects of transverse shear and normal deformations are considered and the equations of motion are derived using the principle of virtual work. A power law distribution is used to explain the variation of mechanical and physical properties through the thickness of the functionally graded plate. Governing equations are then derived and the natural frequencies and the corresponding mode shapes are obtained up to the fifth-order expansion. The numerical results are given in detail and compared with the existing works. It is shown that when fifth-order expansion is used, the results of this theory for natural frequencies of thick functionally graded rectangular plates are very close to those obtained from three dimensional elasticity theory.
•A novel method using elastic plates to promote bubble departure was proposed.•The bubble departure within elastic plates had the shorter time and higher frequency.•The fluid velocity within elastic ...plates was much higher than that of rigid ones.•The bubble necking radius fitted with the power function curve of r∼τα (α ∼ 0.82–0.85).
Bubble dynamics play a crucial role in multiphase flow system. A quick bubble departure process is adorable in processes such as gas evolution and boiling heat transfer. Bubble necking is beneficial for high gas production efficiency. However, the formation of bubble necking depends on the balance between surface tension force and buoyancy force, i.e. it is mostly limited to the flow characteristics. Here, a novel method using a pair of elastic plates (made of Polyethylene terephthalate (PET)) which promotes the bubble necking and departure in confined space by oscillation of plates is investigated experimentally based on Particle Image Velocimetry (PIV). The velocity of bubble and liquid throughout the process within elastic plates (the thickness of 0.05 mm and the length of 12 mm) are about 5 and 35 times higher than that within rigid plates (the thickness of 0.5 mm and the same length). Plate dynamics with different rigidities coupling bubble dynamics are also investigated in detail. The surface tension force for bubble between elastic plates is lowered due to the changed shape during the expansion process of elastic plates caused by bubble growth. The radius of bubble necking versus breaking time is found fitted with the power function line as r∼τα (α varies in the range 0.82–0.85). It is found that the bubble necking rate increased with the length of the plate due to the flow effect caused by the oscillation of plates. Our study reveals that elastic plates benefit bubble departure and liquid replenishment for cases in confined space, showing their potential applications in microfluidic system.
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