Effect Of Element Type Research Articles

The effect of element type and sintering temperature of MFe2O4 sensing electrode on gadolinium doped cerium oxide-based mixed potential triethylamine sensor

For the on-line stable detection of TEA, mixed potential gas sensor based on GDC (gadolinium doped cerium oxide, Ce0.8Gd0.2O1.95) solid electrolyte and MFe2O4 (M = Ni, Cu, Zn) sensing electrode has been fabricated in this work. The influence of element type and sintering temperature of the sensing materials on the sensing performance were mainly discussed, the sensor manufactured with CuFe2O4 sintered at 800 °C generates the highest response (−50.7 mV) to 20 ppm TEA compared with other sensors. The response value changed proportionally with the logarithm of TEA concentration, with the sensitivity of −21.9 and −43.6 mV/decade in the range of 0.5–5 and 5–100 ppm, respectively. The sensor exhibited excellent repeatability towards 2 and 10 ppm TEA for 7 continuous tests, and great selectivity for 10 various gases. Moreover, the sensor also demonstrated good moisture resistance and terrific long-term stability at 500 °C for 30 days continuous work. Based on the excellent sensing properties, this work supplied a stable TEA sensor fabricated with CuFe2O4 sintered at 800 °C, which has a great potential application prospect for the accurate detection towards TEA.

Mesh-Free MLS-Based Error-Recovery Technique for Finite Element Incompressible Elastic Computations

The finite element error and adaptive analysis are implemented in finite element procedures to increase the reliability of numerical analyses. In this paper, the mesh-free error-recovery technique based on moving least squares (MLS) interpolation is applied to recover the errors in the stresses and displacements of incompressible elastic finite element solutions and errors are estimated in energy norms. The effects of element types (triangular and quadrilateral elements) and the formation of patches (mesh-free patch, mesh-dependent element-based patch, and mesh-dependent node-based patch) for error recovery in MLS and conventional least-square interpolation-error quantification are also assessed in this study. Numerical examples of incompressible elasticity, including a problem with singularity, are studied to display the effectiveness and applicability of the mesh-free MLS interpolation-error recovery technique. The mixed formulation (displacement and pressure) is adopted for a finite element analysis of the incompressible elastic problem. The rate of convergence, the effectivity of the error estimation, and modified meshes for desired accuracy are used to assess the effectiveness of the error estimators. The error-convergence rates are computed in the original FEM solution, in the post-processed solution using mesh-free MLS-based displacement, stress recovery, mesh-dependent patch-based least-square-based displacement, and stress recovery (ZZ) as (0.9777, 2.2501, 2.0012, 1.6710 and 1.5436), and (0.9736, 2.0869, 1.6931, 1.8806 and 1.4973), respectively, for four-node quadrilateral, and six-node triangular meshes. It is concluded that displacement-based recovery was more effective in the finite element incompressible elastic analysis than stress-based recovery using mesh-free and mesh-dependent patches.

Energy Absorption Characteristics of Triply Periodic Minimal Surface Lattices

Historically, structural equipment has been studied to determine the impact and protection of its components, and common energy-absorbing materials include honeycomb, foam, bellows, and expansion tubes. According to related analyses, topological metamaterial structures designed based on mathematically known non-self-intersecting three-periodic minimal surfaces (TPMS) may possess superior mechanical properties. It is demonstrated in this study that a solid structure with a TPMS of 10 mm × 10 mm × 10 mm is constructed based on the Schwarz Primitive surface. Analyses were conducted on the effects of element type and modeling conditions on simulation results. Based on the simulation results, the solid element exhibited better analysis accuracy than the shell element. The structure had a better energy absorption capability when its surface thickness was set at approximately 1.31 mm.

Experimental and numerical study on mechanical behavior of high-strength lockbolted friction grip connections

Despite the wide application of high-strength bolts joint in steel bridges, there are still some issues with this jointing technology such as large variation in the bolt preload, looseness of the joint as well as the fatigue problem. In this study, the high-strength lockbolted friction grip (HSLFG) connections were proposed as an alternative and the experimental results indicated that HSLFG connections have comparable mechanical behavior and strength to that of high-strength bolted friction grip (HSBFG) connections. First, the experiments were carried out on four HSLFG connections and four conventional HSBFG connections, in which the mechanical properties of both connections such as the failure modes, load-bearing behavior, and load-strain relationships were obtained and compared. The experimentally results indicate that the preload of the high-strength lockbolts satisfy the requirements of Eurocode3 and JTG D64-2015. Refined finite element (FE) models were established and were verified against the experimental results which proved the FE models could effectively predict the elastic-plastic behavior and positions of rupture of the HSLFG connections. Furthermore, the parametric analysis of FE model was conducted to investigate the effect of element types, friction coefficients on the mechanical property of the HSLFG connections. This research provided a promising strategy for the development requirements of HSLFG connections in steel bridges.

Modelling mode I failure at crack tip with verifications using digital image correlation

Background: Linear elastic fracture mechanics (LEFM) applies to sharp cracks, although crack sites such as holes and slots are often blunt cracks with nonzero widths. The advancement in finite element method (FEM) has enabled the calculation of stress intensity factor (SIF) for unstable crack growth prediction, regardless of crack shape and size, but the calculations often differ from contour to contour. Hence, the purpose of this work is to determine if SIFs computed using commercial FEM have experimentally verifiable advantages over the traditional stress-based modelling approaches in predicting Mode I brittle failure at blunt crack tip. Methods: Experiments and simulations were conducted on brittle Poly(methyl methacrylate) (PMMA) plastic to compare the actual and predicted strain fields and SIFs at crack tip, and the critical force at which unstable crack growth initiates. A centrally straight cracked Brazilian disc made of PMMA was subjected to purely Mode I fracture. Its strain fields were measured from deformed speckle patterns using digital image correlation software. The same disc was modelled using plane stress model in FEM. By applying the critical force, SIFs were then computed using ANSYS pre-meshed crack method at different contours away from the crack tip. The effects of element type, mesh size and crack width on the simulated SIFs were investigated. Results: It was found that the experimental critical load agreed well with LEFM prediction based on PMMA fracture toughness in published literature. Disc failure happened at the first sign of tensile yield at the crack tip in the finite element model with a triangle mesh. Digital image correlation clearly shows the occurrence of unstable crack growth at critical force. It also shows comparable far field strain responses to the FEM model. Conclusions: The computed SIFs were inconsistent, and their usefulness in predicting unstable crack growth requires further investigation.

Current Status of Research on Electrodeposited Ni-W Alloy Coating

This paper discusses the influence of pH value, temperature and current density on the crystalline and amorphous structure of Ni-W alloy coatings during the electroplating process. The relationship between the corrosion resistance of Ni-W alloy coating and its crystal structure is discussed. In addition, the most common types of ternary systems and composite coatings for electrodeposited Ni-W alloy coatings are introduced. The effects of element types and contents on the hardness, wear resistance, corrosion resistance and thermal stability of Ni-W alloy coatings are analyzed. Finally, the current problems and development directions of Ni-W alloy coatings are proposed.

Experimental evaluation of force analogy method (FAM) by element type

The force analogy method (FAM) is considered as one of the most time-saving and cost-efficient methods for analyzing frames. Through a set of assumptions and restoring forces, FAM analyzes nonlinear frames responses through Hooke’s law. This study evaluates the effect of element type on FAM through numerical and experimental tests. The conventional Euler Bernoulli (EB) element is replaced by the Timoshenko (TS) beam-column element and the results are interpreted and compared with experimental findings. Three experimental tests were conducted for benchmarking and comparison purposes via 2D aluminum frames. The results indicated that during the analysis, when the frame response is in the linear region, there is no difference between the element types in the response of the frames. When the frame entered the plastic region, the frames which were analyzed by the TS element revealed closer responses to the experimental outcomes. The gap between the results of the frame which was analyzed by EB and TS enlarged especially when the frame experienced a sharp or huge rotation of more than 0.2 rad. The final recorded deformations based on the TS element revealed an accuracy between 98.05% to 98.65%, while the EB element showed 14.66% to 45.14% for rotations of more than 0.2 rad at plastic hinge locations (PHLs).

The Effect of Element Types on Force Analogy Method Analysis

In this study, the seismic performance of a 2D portal frame subjected to the recorded seismic ground motions of the Northridge 1994 earthquake was evaluated by the force analogy method (FAM) with different element types. To increase the accuracy of FAM, Timoshenko (TS) elements were employed instead of the classical Euler Bernoulli (EB) elements, to revert the shear deformations that are neglected in EB elements. To perform evaluation, the same material and section properties were considered and the same portal frame was analyzed with different element lengths, from 0.5 to 7.0 m in 0.5 m steps.

Effect of element types on the glass forming ability of Al-TM-RE ternary metallic glasses using electron structure guiding

The effect of TM (transition metal, Fe, Co, Ni) and RE (rare earth, La, Ce, Sm, Y, Gd, Er, Pr) element types on the glass forming ability (GFA) of Al86TM9RE5 ternary alloy system has been studied based on the concept of Fermi sphere - Brillouin zone interaction. The effect of TM element is primarily on the electron hybridization between Al atoms and TM atoms, affecting the diameter of the Fermi sphere (2KF). And the effect of RE element is mainly a change in the diameter of the pseudo-Brillouin zone (KP). Their effects on the Fermi level and Brillouin zone size are monitored using spectroscopy experiments. The |δ| = |KP-2KF| criterion was proposed to evaluate the effect of GFA on the TM and RE elements. This criterion guided us to select an optimal GFA element (Al86Ni9Y5) in the Al-TM-RE ternary alloy system and was confirmed by the experimental results.

Effect of Element Types on Failure Prediction Using a Stress-Based Forming Limit Curve

Strain-based forming limit diagrams (FLDs) are the traditional tool used to characterize the formability of materials for sheet metal forming processes. However, this failure criterion exhibits a significant strain path dependence. Alternatively, stress-based FLDs have been proposed and shown to be less sensitive to the deformation path. The stress-based failure criterion can be conveniently implemented in numerical simulations. However, for reliable numerical modeling, the sensitivity of the models to the selection of discretization parameters, in particular, the element type must be assessed. In this paper, Marciniak tests have been numerically simulated to investigate failure prediction using three different element types (shell, solid, and solid-shell). Seven different specimen geometries were modeled in order to vary the loading paths. The results show that despite differences in stress calculation assumptions, shell, solid, and solid-shell elements do not provide differences in failure prediction when a stress-based failure criterion is used.

Convergence Studies of Thermal and Electromagnetic Transient Quench Analysis of 11 GeV Super High Momentum Spectrometer Superconducting Magnets in Jefferson Lab

This paper presents results of convergence studies of transient thermal and electromagnetic quench analysis of five Super High Momentum Spectrometer (SHMS) superconducting magnets: HB, Q1, Q2, Q3, and Dipole, using Vector Fields Quench analysis codes. The convergence of the hot spot temperature and solution solve times were used to investigate the effects of element types, mesh densities, and tolerance criteria. The comparisons between tetrahedral elements and hexahedral elements was studied, and their advantages and disadvantages were discussed. Based on the results of convergence studies, a meshing guideline for coils is presented. The impact of iteration tolerance to the hot spot temperature was also explored, and it is found that tight tolerances result in extremely long solve times with only marginal improvements in the results.

Effects of element type and spatial grouping on symmetry detection.

The influence of local and global attributes of symmetric patterns on the perceptual salience of symmetry was investigated. After tachistoscopic viewing, subjects discriminated between symmetric and either random patterns (experiment 1) or their perturbed counterparts (experiment 2) created by replacing one third of the mirror element-pairs of symmetric stimuli with 'random' elements. In general, it was found that perceptibility of symmetry, measured by response time and detection accuracy, was not influenced in a consistent way by type of pattern element (dots or line segments oriented vertically, horizontally, obliquely, or in all three orientations about the symmetry axis). Nor did axis orientation (vertical, horizontal, oblique), advance knowledge of axis orientation, practice effects, or subject sophistication differentially affect detection. A highly salient global percept of symmetry emerged, on the other hand, when elements were clustered together within a pattern, or grouped in symmetric pairs along a single symmetry axis or two orthogonal axes. Results suggest that mirror symmetry is detected preattentively, presumably by some kind of integral code which emerges from the interaction between display elements and the way they are organized spatially. It is proposed that symmetry is coded and signalled by the same spatial grouping processes as those responsible for construction of the full primal sketch.