Dynamic Plate Research Articles

Theoretical and experimental analysis of dynamic plate heat exchanger: Non-retrofit configuration

This document theoretically and experimentally describes a dynamic plate heat exchanger, a device that can decrease or eliminate heat exchanger performance and efficiency losses associated with transient changes in flow rates and other sources of imbalance. Heat exchanger constraints may represent the most restrictive transient response constraints in a process and thereby compromise the agility and responsiveness of processes. These constraints include thermal stresses, expansion, or temperature changes in the devices or their near neighbors in the flow process. The proposed design is capable of leveling varying conditions such that the exit temperatures remain fixed despite the changes in inlet conditions. Experimental and theoretical results indicate that the proposed design can respond to changes in process flow rates with a near-zero time constant.

Dynamic Buckling Response of Long Plates for the Prediction of Local Plate Buckling of Corrugated Core Sandwich Columns

An analytical model predicting the dynamic local buckling failure of plates with a large dimension in the longitudinal direction compressed at a constant rate was proposed. The model began with the hypothesis that the proposed analytical approach could be an alternative methodology to approximate the dynamic local plate buckling response of constituent plates of corrugated core sandwich columns. Prior to the model development, four preliminary finite-element (FE) simulations were conducted to observe the typical dynamic response of the sandwich columns having thin core web plates or thin face sheets. From the simulations, several wrinkles with a regular pattern were generated, and then one of the wrinkles grew excessively to a failure. Accordingly, the proposed model considered an imaginary patch plate on a long plate simulating a face sheet or a core web plate. The size of the patch plate was predefined so as to encompass the major growing wrinkle, and the out-of-plane displacement was calculated till load drop. The verification of the proposed model was followed by comparison with the FE calculations. The model was satisfactory in predicting maximum forces and times-to-failure, but some discrepancies were found when postcritical behavior and plasticity were involved. The sources of the discrepancies were discussed.

Dynamic Response of Three-Layered, Annular Plate with Thick Core

Abstract The paper presents the solutions, calculation results and dynamic observations of three-layers, annular plate with thick core subjected to increasing in time load. The presented solutions use approximate methods: orthogonalization method and finite difference method in analytical and numerical solution of the problem, and finite element method. The observed phenomenon of the reduction of critical load values of the plates, in which the buckling mode is not global and there are different additional deflections of respective plate layers was comprehensively analysed in order to evaluate the critical state and supercritical plate behaviour. The critical deformation could have a form with strong deformation in the region of the loaded plate edge. The observation of the dynamic behaviour of plates, which buckling modes have circumferential waves is an important element of the analysis. Presented in this work the analytical and numerical solution to the problem of dynamic plate deflection was generalized on the case of plates with buckling waves in circumferential direction.

In vitro evaluation of translating and rotating plates using a robot testing system under follower load.

Various modifications to standard "rigid" anterior cervical plate designs (constrained plate) have been developed that allow for some degree of axial translation and/or rotation of the plate (semi-constrained plate)-theoretically promoting proper load sharing with the graft and improved fusion rates. However, previous studies about rigid and dynamic plates have not examined the influence of simulated muscle loading. The objective of this study was to compare rigid, translating, and rotating plates for single-level corpectomy procedures using a robot testing system with follower load. In-vitro biomechanical test. N=15 fresh-frozen human (C3-7) cervical specimens were biomechanically tested. The follower load was applied to the specimens at the neutral position from 0 to 100N. Specimens were randomized into a rigid plate group, a translating plate group and a rotating plate group and then tested in flexion, extension, lateral bending and axial rotation to a pure moment target of 2.0Nm under 100N of follower load. Range of motion, load sharing, and adjacent level effects were analyzed using a repeated measures analysis of variance (ANOVA). No significant differences were observed between the translating plate and the rigid plate on load sharing at neutral position and C4-6 ROM, but the translating plate was able to maintain load through the graft at a desired level during flexion. The rotating plate shared less load than rigid and translating plates in the neutral position, but cannot maintain the graft load during flexion. This study demonstrated that, in the presence of simulated muscle loading (follower load), the translating plate demonstrated superior performance for load sharing compared to the rigid and rotating plates.

Callus massage after distraction osteogenesis using the concept of lengthening then dynamic plating.

Correction of complex deformities is a challenging procedure. Long-term wearing of a fixator after correction and lengthening are inconvenient and has a high rate of complication. The goals of the surgical treatment in the presented case were: (1) correction of the deformity and lengthening of the left leg by the Taylor spatial frame (TSF, Smith and Nephew, Marl, Germany); (2) reduction in the time the patient wears the TSF by changing the fixation system to a plate (lengthening then plating—LTP) and using a locking compression plate in conjunction with the 5.0 dynamic locking screws in order to accelerate bone healing.

Development of dynamic well plate system for cell culture with mechanical stimulus of shear stress and magnetic field

Investigating the effects of various physical stimuli on cells is important for improving the efficiency of tissue repair and regeneration. In this research, we developed a dynamic well plate system by integrating the advantages of conventional well plates and a bioreactor to provide simultaneous physical stimuli of shear stress and a static magnetic field. The dynamic well plate involving perfusion of culture medium can control hydrodynamic shear while retaining the inherent simplicity of conventional well plates. The specific well plate cover was designed to load shear stress on cells during cultivation and was built to fit over a standard six-well plate. Additionally, to investigate the effects of a magnetic field on cell proliferation, a static neodymium magnet was placed beneath each well. To assess the system developed, calf pulmonary artery endothelial (CPAE) cells were cultured using the developed system. CPAE cells under hydrodynamic shear stress conditions were elongated and aligned in the direction of the flow and the magnetic field enhanced CPAE cell proliferation. Simultaneous application of a magnetic field and shear flow in CPAE cell cultivation allowed the development of optimized culture conditions, initially for cell proliferation and then for functional expression, such as cell shape changes.

Continuous inter-laminar stresses for regular and inverse geometrically non linear dynamic and static analyses of laminated plates and shells

This study presents an orthotropic laminated finite element with continuous stress distribution along transverse direction applied to geometrically non linear analysis of static and dynamic plates and shells. The kinematic description is total Lagrangian based on positions and generalized vectors which avoids the use of the finite rotation concept. Therefore, the loss of precision that may appears when reference updating takes place is not present. Moreover, there is no necessity to transform velocity and acceleration from the spatial to the material reference frame and the Newmark method can be applied.Using generalized vectors introduces constant thickness variation and complete 3D constitutive relation. Without increasing the number of degrees of freedom, the equilibrium of laminas parallel to the reference surface is applied to achieve continuous stress distribution along transverse direction. A curved triangular finite element with cubic approximation is adopted also avoiding membrane locking.Static examples are designed to check the absence of locking and to verify the quality of transverse stress distribution for thin and moderately thick orthotropic plates and shells. Dynamic examples show the ability of total Lagrangian formulations on solving general and inverse dynamic problems with energy conservation.

Dynamic locking plates provide symmetric axial dynamization to stimulate fracture healing.

Axial dynamization of an osteosynthesis construct can promote fracture healing. This biomechanical study evaluated a novel dynamic locking plate that derives symmetric axial dynamization by elastic suspension of locking holes within the plate. Standard locked and dynamic plating constructs were tested in a diaphyseal bridge-plating model of the femoral diaphysis to determine the amount and symmetry of interfragmentary motion under axial loading, and to assess construct stiffness under axial loading, torsion, and bending. Subsequently, constructs were loaded until failure to determine construct strength and failure modes. Finally, strength tests were repeated in osteoporotic bone surrogates. One body-weight axial loading of standard locked constructs produced asymmetric interfragmentary motion that was over three times smaller at the near cortex (0.1 ± 0.01 mm) than at the far cortex (0.32 ± 0.02 mm). Compared to standard locked constructs, dynamic plating constructs enhanced motion by 0.32 mm at the near cortex and by 0.33 mm at the far cortex and yielded a 77% lower axial stiffness (p < 0.001). Dynamic plating constructs were at least as strong as standard locked constructs under all test conditions. In conclusion, dynamic locking plates symmetrically enhance interfragmentary motion, deliver controlled axial dynamization, and are at least comparable in strength to standard locked constructs. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1218-1225, 2015.

Comparison of Multiple Sensor Deflection Data From Lightweight and Falling Weight Deflectometer Tests on Layered Soil

The lightweight deflectometer (LWD) and falling weight deflectometer (FWD) are in situ dynamic plate load tests used to estimate the stiffness and elastic moduli of bound and unbound materials. The inclusion of radial offset sensors with LWD testing stemmed from the well-established FWD testing method of using deflections at the load plate center and at radial offsets to generate a deflection bowl to estimate the moduli of individual layers in a multi-layer system. Due to the similarities between the LWD and FWD tests, several studies have explored the relationship between center deflection results of the two tests. However, little research exists in the literature addressing LWD testing with multiple sensors and how well those deflections correlate with FWD deflections at the same radial offsets. To this end, 114 multiple sensor LWD and FWD tests were performed on stabilized base materials at three sites and rigorously analyzed to determine if there is a consistent relationship between LWD and FWD center and radial offset deflections across all sites and if the estimated moduli from the same backcalculation approach produce similar or correlated results. The results demonstrated that while relationships are site specific for deflections and moduli estimated from the load plate center, a consistent relationship across all sites is demonstrated from the radial offset measurements. Finite element analysis was conducted to understand the difference in induced strains from the two tests to support and better understand the observed differences in FWD and LWD deflections and backcalculated layer moduli.

Dynamic equations for a fully anisotropic piezoelectric rectangular plate

A hierarchy of dynamic plate equations based on the three dimensional piezoelectric theory is derived for a fully anisotropic piezoelectric rectangular plate. Using power series expansions results in sets of equations that may be truncated to arbitrary order, where each order set is hyperbolic, variationally consistent and asymptotically correct (to all studied orders). Numerical examples for eigenfrequencies and plots on mode shapes, electric potential and stress distributions curves are presented for orthotropic plate structures. The results illustrate that the present approach renders benchmark solutions provided higher order truncations are used, and act as engineering plate equations using low order truncation.

Dynamic Response of Three-Layered Annular Plate with Imperfections

Abstract This paper presents the imperfection sensitivity of annular plate with three-layered structure. The plate composed of thin elastic facings and a thicker elastic core is loaded in facing plane. The classical issue of a three-layered plate was solved for dynamic deflection problem using the approximation methods: orthogonalization and finite difference. The solution includes the axisymmetric and asymmetric plate modes of the dynamic stability loss. The evaluation of the rate of plate sensitivity to imperfection of plate preliminary geometry has been enriched by the analysis of plate models built of finite elements. The ABAQUS program has been used. The numerous calculation results in the form of deflection characteristics, buckling modes, values of critical parameters create the view of response of dynamic plate structure with different rate of imperfection and linear in time loading growth, too.

Elastically suspending the screw holes of a locked osteosynthesis plate can dampen impact loads.

Impact damping by elastic fixation is a principal engineering strategy to increase the durability of load-bearing structures exposed to prolonged dynamic loading. This biomechanical study evaluated axial impact damping provided by a novel dynamic locking plate. In this design, locking screw holes are elastically suspended within a silicone envelope inside the locking plate. Axial impact damping was assessed for 3 distinct fixation constructs applied to bridge a 10-mm fracture gap of a femoral diaphysis surrogate: a standard locking plate, a dynamic locking plate, and an Ilizarov ring fixator. First, the 3 fixation constructs were characterized by determining their axial stiffness. Subsequently, constructs were subjected to a range of axial impact loads to quantify damping of force transmission. Compared with standard locked plating constructs, dynamic plating constructs were 58% less stiff (P < .01) and Ilizarov constructs were 88% less stiff (P < .01). Impact damping correlated inversely with construct stiffness. Compared with standard plating, dynamic plating constructs and Ilizarov constructs dampened the transmission of impact loads by up to 48% (P < .01) and 74% (P < .01), respectively. In conclusion, lower construct stiffness correlated with superior damping of axial impact loads. Dynamic locking plates provide significantly greater impact damping compared with standard locking plates.

Transient dynamic analysis of shear deformable shallow shells using the boundary element method

Dynamic plate bending problems appear on civil, mechanical, aerospatial and naval applications. The complexity involved in the dynamic response of plates brings many challenges from a mathematical standpoint. In this work, the transient dynamic analysis of elastic shallow shells under uniformly distributed pressure loads, using a dual reciprocity boundary element formulation, is presented. A boundary element formulation based on a direct time-domain formulation using elastostatic fundamental solutions was used. Effects of shear deformation and rotatory inertia were included in the formulation. Shallow shells are modeled coupling boundary element formulation of shear deformable plate and two-dimensional plane stress elasticity. Domain integrals related to inertial terms were treated using the Dual Reciprocity Boundary Element Method. Numerical examples are presented to demonstrate the efficiency and accuracy of the proposed formulation.

Composite NiB–Graphite and NiB–PTFE Surface Coatings Deposited by the Dynamic Chemical Plating Technique

Dynamic chemical plating (DCP) is an alternative for producing metallic deposits on nonconductive materials and can be considered as a modified electroless coating process. This article describes the formation of composite NiB–particle films by the DCP technique. The particles used were micrometric graphite (1–2 µm) or PTFE (50–500 nm). The conditions for production of these coatings are presented along with the deposition rates, surface morphology, friction properties, and the degree of particle incorporation into the films.

Contact Analysis for Coupling of Plates and Screws in Fracture Fixation of Cortical Bone

Internal fixation is a common treatment for bone fracture. Bone fracture occurs due to different reasons such as motor vehicle accidents, falling,...etc. The treatment is performed by fixing plate and screws to the fracture site. Lack of stability of the implants (plates and screws) may lead to delay in healing or failure of treatment. Micro-motion between the implant and the bone may cause formation of fibrous tissue around the screw which will lead to implant loosening. On the other hands, firm fixing of the conventional implants (Dynamic Compression Plates) may lead to delay resorption and delay in healing. Recently, Locked Compression Plates were introduced to get over the shortcomings of the existing Dynamic Plates. In Locked Plates the hole and screw head were threaded to provide more stability and reduce contact with the bone surface. In this communication we conducted computational analysis to compare the stability of both sets of implants. Results have revealed that Locked Plates provide more stable fixation and resistance to micro-motion. However, stress shielding might occur which will delay healing. Future designs of the Locked Plates can focus on improving stability and reducing damage to blood supply which will shorten the Short Research Article Gailani et al.; AIR, 4(2): 94-101, 2015; Article no.AIR.2015.065 95 healing period. Computational analysis (finite element analysis) can be effectively used to guide these future designs.

Manufacturing Ternary Alloy NiBP-PTFE Composite Coatings by Dynamic Chemical Plating Process

The dynamic chemical plating technique is used to deposit NiBP coatings with incorporation of polytetrafluoroethylene (PTFE) particles. This technique is faster and simpler to perform compared to other electroless deposition techniques. Using a double nozzle gun, metal salt solution and reducing agents are sprayed to the surface, forming a deposit. Using scanning electron microscopy morphology of the coatings was studied. By dynamic chemical plating technique films with maximum incorporation rate of vol % 21 PTFE were deposited. Tribological studies were conducted by a ball/surface tribometer, at different applied loads (5, 15, 30, 45, 60 N). Deposited films exhibited interesting tribological properties with a friction coefficient of 0.3 for a film containing vol % 21 PTFE. The coating has a tendency to peel off locally at high applied loads. Friction coefficient increased with decreasing PTFE content.

Malaligned dynamic anterior cervical plate: a biomechanical analysis of effectiveness.

Biomechanical evaluation. To evaluate the kinematic and load-sharing differences of dynamic anterior cervical plates when placed in-line at 0° and off-axis at 20°. The use of dynamic anterior cervical plating systems has recently gained popularity due to the theoretical benefit of improved load sharing with graft subsidence. Occasionally, due to anatomical restraints, the anterior cervical plate may be placed off-axis in the coronal plane. This may potentially decrease the dynamization capability of the plate, leading to less load sharing and potentially decreased fusion rates. The purpose of this study was to comprehensively evaluate the kinematic and load-sharing differences of a dynamic plate placed in-line versus off-axis in the coronal plane. Thirteen fresh-frozen human cadaveric cervical spines (C2-T1) were used. Nondestructive range-of-motion testing was performed with a pneumatically controlled spine simulator in flexion/extension, lateral bending, and axial rotation using the OptoTrak motion measurement system. A C5 corpectomy was performed, and a custom interbody spacer with an integrated load cell collected load-sharing data under axial compression at varying loads. A dynamic anterior cervical plate was placed in-line at 0° and then off-axis at 20°. Testing conditions ensued using a full-length spacer, followed by simulated subsidence by removing 10% of the height of the original spacer. There were no kinematic differences noted in the in-line model versus the off-axis model. After simulated subsidence, the small decreases in stiffness and increases in motion were similar whether the plate was placed in-line or off-axis in all 3 planes of motion. There were also no significant differences in the load-sharing characteristics of the in-line plate versus the off-axis plate in either the full-length model or the subsided interbody model. This study suggests that off-axis dynamic plate positioning does not significantly impact construct kinematics or graft load sharing. As such, we do not recommend removal or repositioning of an off-axis placed dynamic plate because the kinematic and load-sharing biomechanical properties are similar. N/A.

Technique of bisegmental anterior cervical interbody fusion with dynamic hybrid plates

According to contemporary scientific literature dynamic cervical plates (DCP) are used to perform anterior cervical interbody fusion (ACIF) in cases of the cervical spine (CS) injuries and diseases more frequently in recent years. They dif-ferentiate such types of DP as translational, rotational and dynamic hybrid plates (DHP). Results of ACIF with rotational and translational DP application are widely reported in publications whereas information on analysis of translational-rotational DHP application is absent. Objective: an analysis of outcomes of clinical applica-tion of the developed cervical translational-rotational DHP in cases of surgical treatment of the cervical spine injuries and diseases. Methods: Outcomes of 11patietnts suffered due to cervical spine injuries and diseases were investigated in 8 (72,7 %) and in 3 (27,3 %) cases respectively. There were 7 (63,6 %) men and 4 (36,4 %) women. Age of patients ranged from 23 to 57years (mean age 42,4 years). One patient was excluded from our investigation because of death postoperatively. In all cases two-level ACIF was performed. The translational-rotational DHP and vertical cylindrical meshed cages (VCMC) developed at the SI «Sytenko Insitute for Spine and Joints Pathology of the NAMS of Ukraine» were used in all patients. Results: developed technique of the ACIF by means of translational-rotational DHP allowed achieving positive clinical outcomes in 90 % of cases, stable fixation in 100 % of cases, and preservation of adequate position of fixing constructs in 90 % of cases. Solid interbody fusion was achieved in all 100 % cases in optimal terms due to dynamic compression of implant within interbody space and propor-tional load sharing between all implants during entire period of treatment. The value of segmental cervical sagittal contour decreased on 2.76 degree an average during observation time that did not reflect on clinical outcomes. It was found that postoperatively translational and rotational types of dynamization started simulta-neously that is confirmed by synchronous change of screw angles in the cranial and caudal pairs of holes with the movement of the plate relatively to the screws in the oblong holes. Conclusions: two-level ACIF with using of the developed transla-tional-rotational DHP allows achieving stable fixation, high fusion rates and en-couraging clinical outcomes.

Analysis of Kinematics and Dynamics of 3UPU/PU Parallel Platform Used in Automatic Wave Compensation

3UPU/PU parallel platform is able to achieve a linear and two rotating motion (3-DOF ) platform,it can used in automatic wave compensation of ship deck equipment. The compensation platform is composed of dynamic and static plate, hydraulic cylinder and driven chain parts; it has strong capacity , simple structure and suitable for most conditions. This paper analysis the motion of the platform using one order and two order influence coefficient, establishes the dynamic model of this platform using the Newton Euler method , obtained the velocity, acceleration and force curve by simulating calculation, lay the foundation for the stable platform’s further dynamic analysis and control.

ОСЛОЖНЕНИЯ ВЕНТРАЛЬНОЙ МЕЖТЕЛОВОЙ ФИКСАЦИИ ШЕЙНЫХ ПОЗВОНКОВ ДИНАМИЧЕСКИМИ ПЛАСТИНАМИ

Dynamic cervical plates, due to their constructive features, provide more proportional load sharing on interbody support that optimizes interbody healing after anterior cervical interbody fusion in the surgical treatment of injuries and diseases of the cervical spine. However, complication rate after their application remains sufficiently high. Analysis of complications of anterior interbody fusion with dynamic cervical plates was performed with respect to their constructive features and the option of interbody support restoration. Complications specific to each type of dynamic cervical plate were determined.