Linking Model-Based Definition and Non-Intrusive Finite Element Analysis for Automated Variation Simulation

ABSTRACTThis paper presents the analytical methods of slope-stabilising piles using the three-dimensional (3-D) finite element (FE) analysis with the strength reduction method (SRM). This 3-D FE model is employed to overcome the limitations observed in two-dimensional (2-D) FE analysis. The solutions obtained from 3-D FE analyses are verified to be less conservative in this paper. The 3-D analysis is considered to be of particular importance to pile-slope problems. The soil that flows between piles cannot be taken account properly in the 2-D FE analysis. The method adopted in this paper can avoid the assumption of soil movement and the pressure distribution along the piles subjected to soil movement. The numerical analysis employs the Mohr–Coulomb failure criterion with the strength reduction technique for soil and an elastic member for piles. The spacing effect of the pile is considered in the 3-D model, the S/D (S: centre to centre, D: diameter of pile) ratio, equal to 4.0, is found to be equivalent to the single pile stabilisation. The middle portion of the slope is identified as the optimal location to place the piles. The proper length of the pile, which can be used to stabilise the slope, is also examined using 3-D FE analyses. It is concluded that L/H greater or equal 0.70 is recommended (L: pile length, H: slope height). The numerical analyses are conducted based on a coupled analysis, which simultaneously considers both the slope stability and the pile response. The failure mechanisms of the pile-slope system subjected to the pile locations, pile head conditions and pile length are each discussed. The contact pressure, shear force and moment along the piles are presented to illustrate the pile stabilising mechanism herein.

This paper is about predicting the noise and vibrations for railways project in Malaysia by using Finite Element Analysis method. In recent years, Malaysia is massively developing railways industry. This has created a great awareness in the public, regarding noise and vibration from railways trains during operations are generated from the rolling interaction of the wheels with the rails. Additional noise may be generated from brake squeals during braking at the stations and curved segments of the rail alignments. Over the years, it is relatively easy to measure the acoustic sound power of a train and to calculate noise levels. However, it would be advantageous to be able to reliably and efficiently predict the noise and vibration impact resulting from proposed railways projects. Comprehensive noise and vibration shall be predicted to determine noise and vibration levels along the entire track alignment to ensure that noise and vibration levels shall comply with Malaysia Department of Environment (DOE) approved limits. The result of analyses can be used to identify and to design noise and vibration mitigation measures for the entire railway project. Several methods have evolved to predict noise and vibration from various operational sources, but their suitability for prediction of noise and vibration from railways trains is not well known and has not yet been thoroughly tested. This study document finite element analysis undertaken for the noise and vibration aspects of the viaduct design of the railways track. Data and inputs for finite element model and analysis are including the aspect of “Geometry, atmospheric, ground effect, analysis type and boundary conditions”, as mentioned by Makarewicz (1998) and Lamancusa (2009). A comparison of finite element model and analysis will be conducted by adding the additional aspects of “Material properties and applied loads”, which to be determined as better accuracy of predicting noise and vibration from railways train.

In the reinforced concrete column to footing connection design, the region around the column is exposed to punching shear failure. This is an undesirable failure since it results in a brittle failure and it governs the strength of the footing in column to footing connection. The shear stresses that act around the perimeter of the column tend to punch through the footing and develop a failure surface in the form of a truncated cone or pyramid shape.In this research, a nonlinear finite element modelling and analysis of the punching shear capacity of the reinforced concrete column to footing connection is conducted. The modelling of the reinforced concrete footing is based on existing literature on the experimental investigation to support the finite element analysis output. The modelling is conducted by using the ABAQUS software. The material used in modelling is modelled considering the nonlinear effects, for concrete material behaviour defined based on the concrete damage plasticity model and reinforced steel model as an elastic–perfectly plastic material. The validity of finite element analysis has been verified through comparison with available experimental data from other researchers. Four different reinforced concrete columns to footing connections have been model numerically. A systematic parametric study of the material parameters compressive strength and flexural reinforcement ratio is carried out in this research to identify the effects of the material parameters on punching shear strength of footing in column to footing connection.KeywordsColumn–footing connectionPunching shearReinforced concreteMaterial parametersFinite element analysis

ABSTRACTStructural strength calculation by finite element analysis (FEA) is increasingly important in design and approval process. In recently developed DNV GL guidelines, procedures for different types of FEA including global strength analysis, cargo hold analysis and fine mesh analysis are provided. These modern guidelines define appropriate loading, boundary conditions and mesh size for FEA to be used with acceptance criteria in the rules. Traditionally, cargo hold and global strength analysis in ship design were dealt with separate finite element (FE) models and analysis approaches. But using same mesh and load cases, the cargo hold FE model has to deliver identical results as the global FE model. The key success factors for suitability of results, particularly for open deck ships under torsion loads, are related to the correct application of boundary conditions on cargo hold FE model. Results from testing this approach for a bulk carrier and a container ship are reported.

The mechanical competence of a bone depends on its density, its geometry and its internal trabecular microarchitecture. The gold standard to determine bone competence is an experimental, mechanical test. Direct mechanical testing is a straight-forward procedure, but is limited by its destructiveness. For the clinician, the prediction of bone quality for individual patients is, so far, more or less restricted to the quantitative analysis of bone density alone. Finite element (FE) analysis of bone can be used as a tool to non-destructively assess bone competence. FE analysis is a computational technique; it is the most widely used method in engineering for structural analysis. With FE analysis it is possible to perform a 'virtual experiment', i.e. the simulation of a mechanical test in great detail and with high precision. What is needed for that are, first, in vivo imaging capabilities to assess bone structure with adequate resolution, and second, appropriate software to solve the image-based FE models [1]. Both requirements have seen a tremendous development over the last years. The last decade has seen the commercial introduction and proliferation of non-destructive microstructural imaging systems such as desktop micro-computed tomography (µCT), which allow easy and relatively inexpensive access to the 3D microarchitecture of bone [2]. Furthermore, the introduction of new computational techniques has allowed to solve the increasingly large FE models, that represent bone in more and more detail [3, 4]. With the recent advent of microstructural in vivo patient imaging systems, these methodologies have reached a level that it is now becoming possible to accurately assess bone strength in humans. Although most applications are still in an experimental setting, it has been clearly demonstrated that it is possible to use these techniques in a clinical setting [5]. The high level of automation, the continuing increase in computational power, and above all the improved predictive capacity over predictions based on bone mass, make clear that there is great potential in the clinical arena for in vivo FE analyses Ideally, the development of in vivo imaging systems with microstructural resolution better than 50 mm would allow measurement of patients at different time points and at different anatomical sites. Unfortunately, such systems are not yet available, but the resolution at peripheral sites has reached a level (80 mm) that allows elucidation of individual microstructural bone elements. Whether a resolution of 50 mm in vivo will be reached using conventional CT technology remains to be seen as the required doses may be too high. With respect to these dose considerations, MRI may have considerable potential for future clinical applications to overcome some of the limitations with X-ray CT. With the advent of new clinical MRI systems with higher field strengths, and the introduction of fast parallel-imaging acquisition techniques, higher resolutions in MRI will be possible with comparable image quality and without the adverse effects of ionizing radiation. With these patient scanners, it will be possible to monitor changes in the microarchitectural aspects of bone quality in vivo. In combination with FE analysis it will also allow to predict the mechanical competence of whole bones in the course of age- and disease-related bone loss and osteoporosis. We expect these findings to improve our understanding of the influence of densitometric, morphological but also loading factors in the etiology of spontaneous fractures of the hip, the spine, and the radius. Eventually, this improved understanding may lead to more successful approaches in the prevention of age- and disease-related fractures.

This paper presents the finite element and wavefront error analysis with reverse engineering of the primary mirror of a small space telescope experimental model. The experimental space telescope with 280mm diameter primary mirror has been assembled and aligned in 2011, but the measured system optical performance and wavefront error did not achieve the goal. In order to find out the root causes, static structure finite element analysis (FEA) has been applied to analyze the structure model of the primary mirror assembly. Several assuming effects which may cause deformation of the primary mirror have been proposed, such as gravity effect, flexures bonding effect, thermal expansion effect, etc. According to each assuming effect, we establish a corresponding model and boundary condition setup, and the numerical model will be analyzed by finite element method (FEM) software and opto-mechanical analysis software to obtain numerical wavefront error and Zernike polynomials. Now new assumption of the flexures bonding effect is proposed, and we adopt reverse engineering to verify this effect. Finally, the numerically synthetic system wavefront error will be compared with measured system wavefront error of the telescope. By analyzing and realizing these deformation effects of the primary mirror, the opto-mechanical design and telescope assembly workmanship will be refined, and improve the telescope optical performance.

Objective To discuss application of finite element (FE) analysis in design of orthopedic implants for repairing bone defects in revision total knee arthroplasty (RTKA).Methods A healthy 25 year-old male volunteer,170 cm in height and 62 kg in weight,was enrolled in the present study.First 3D FE models of the knee joint were reconstructed on the basis of the spiral CT scans of the male volunteer.Five FE models were constructed of the wedge-shaped bone defects in the medial tibia plateau (5.0,7.5,10.0,12.5and 15.0 mm in height respectively).In simulated repair of the bone defects in FE models,cement (in group 1),cement with reinforcement screws (in group 2) and metal augmentation (in group 3) were used.Loading and boundary conditions were set to reflect the real situations.The displacement between the bone-cement interfaces and the maximum shear stress in the cement between the bone-cement interfaces were investigated and compared.Results When the defects were 12.5 mm and 15.0 mm,the displacement exceeded the threshold of loosening in groups 1 and 2,higher than 150 μm.When the defects were 7.5 mm and 10.0 mm,the displacements were higher than 150 μm in group 1,but lower than 150 μm in group 2.When the defect was 5.0 mm,the displacement was at the threshold of loosening in all groups.In all groups,the cement maximum shear stress increased as the defects became larger.The maximum shear stresses in group 2 were lower by 21％,16％,11％,9％,and 7％ than those in group 1 as the defect sizes decreased accordingly.Group 3 showed the lowest maximum shear stress.Conclusion In the FE models of repairing bone defects in RTKA,cement with reinforcement screws can be used to repair wedge-shaped bone defects no larger than 10.0 mm and result in fine biomechanical stability because higher displacement and interface shear stress imply a high incidence of loosening. Key words: Knee joint; Arthroplasty; Finite element analysis

PurposeAlthough it has been recognized that the medial meniscus extrusion (MME) leads to progressive cartilage loss and osteoarthritis (OA), about 20% of cases with MME had minor symptoms and poor progression of knee OA. However, it is still unclear which patients will have minimal symptoms or will not progress to degeneration. The purpose of this study is to compare the effect of the relationship between the MME and Joint line convergence angle (JLCA) on knee stress with the finite element (FE) analysis method.MethodsThe 65 year-old female was taken computer tomography (CT) from thigh to ankle. A 3-dimentional nonlinear FE model was constructed from the patient’s DICOM data. We made the six models, which was different from JLCA and MME. Contact stresses on the surfaces between femoral and tibial cartilages and both side of meniscus are analyzed.ResultsAs the JLCA or MME increased, the stress load on the medial compartment increased. The effect of MME was stronger on the femoral side, while the effect of JLCA was stronger for the tibia and meniscus. If the JLCA was tilted valgus, the stress in the medial compartment did not increase even in the presence of MME.ConclusionsThis study revealed that the MME is associated with increased a stress loading on medial compartment structures. Furthermore, this change was enhanced by the varus tilt of the JLCA. In the case of valgus alignment, the contact pressure of the medial compartment did not increase so much even if with the MME.Level of evidenceLevel V

Objective To explore the establishment of 3D thoracic model by finite element methods, and study the mechanical mechanism of minimally invasive surgery for correcting the chest wall deformity, and provide personalized surgery solution in the future. Methods According to admission and exclusion criteria, we selected 10 cases of pectus carinatum that received chest CT scan. The finite element model of pectus carinatum was established and analyzed by Mimics, ABAQUS, etc. The validity of finite element method for chest wall was verified by comparing the sternal displacement between the simulated values and actual values with the same force. Results The 3D finite element model of pectus carinatum was successfully established and analyzed. The stress distribution of the 10 cases in the posterior ribs was mainly in the 1-6 ribs on both sides, mostly concentrated in the 4th to 6th ribs, and the stress was symmetrical on both sides. Statistical analysis showed that the displacement value of the sternum was correlated, and the validity of the model was verified. Conclusion Mimics, ABAQUS and other finite element modeling and analysis software can effectively establish the thoracic 3D finite element model and mechanical analysis, which can help the further development of personalized minimally invasive surgery for correcting chest wall deformities. Key words: Pectus carinatum; Chest wall deformity; Finite element analysis

Shape Memory Alloys (SMA) are promising materials for actuation in space applications, because of the relatively large deformations and forces that they offer. However, their complex behaviour and interaction of several physical domains (electrical, thermal and mechanical), the study of SMA behaviour is a challenging field. Present work aims at correlating the Finite Element (FE) analysis of SMA with closed form solutions and experimental data. Though sufficient literature is available on closed form solution of SMA, not much detail is available on the Finite element Analysis. In the present work an attempt is made for characterization of SMA through solving the governing equations by established closed form solution, and finally correlating FE results with these data. Extensive experiments were conducted on 0.3mm diameter NiTinol SMA wire at various temperatures and stress conditions and these results were compared with FE analysis conducted using MSC.Marc. A comparison of results from finite element analysis with the experimental data exhibits fairly good agreement.

Coaptation Surface Area and Aortic Regurgitation: The Infinite Potential of Finite Element Analysis

Controlled lateral buckling in offshore pipelines typically gives rise to the combination of internal over-pressure and high longitudinal strains (possibly exceeding 0.4 percent). Engineering critical assessments (ECAs) are commonly conducted during design to determine tolerable sizes for girth weld flaws. ECAs are primarily conducted in accordance with BS 7910, often supplemented by guidance given in DNV-OS-F101 and DNV-FP-F108. DNV-OS-F101 requires that finite element (FE) analysis is conducted when, in the presence of internal over-pressure, the nominal longitudinal strain exceeds 0.4 percent. It recommends a crack driving force assessment, rather than one based on the failure assessment diagram. FE analysis is complicated, time consuming and costly. ECAs are, necessarily, conducted towards the end of the design process, at which point the design loads have been defined, the welding procedures qualified and the material properties quantified. In this context, ECAs and FE are not an ideal combination for the pipeline operator, the designer or the installation contractor. A pipeline subject to internal over-pressure is in a state of bi-axial loading. The combination of internal over-pressure and longitudinal strain appears to become more complicated as the longitudinal strain increases, because of the effect of bi-axial loading on the stress-strain response. An analysis of a relatively simple case, a fully-circumferential, external crack in a cylinder subject to internal over-pressure and longitudinal strain, is presented in order to illustrate the issues with the assessment. Finite element analysis, with and without internal over-pressure, are used to determine the plastic limit load, the crack driving force, and the Option 3 failure assessment curve. The results of the assessment are then compared with an assessment using the Option 2 curve. It is shown that an assessment based Option 2, which does not require FE analysis, can potentially give comparable results to the more detailed assessments, when more accurate stress intensity factor and reference stress (plastic limit load) solutions are used. Finally, the results of the illustrative analysis are used to present an outline of suggested revisions to the guidance in DNV-OS-F101, to reduce the need for FE analysis.

Finite element (FE) analysis is an exciting computational technique that permits the collection of biomechanical data. It is widely utilized in industrial engineering, anthropology, comparative anatomy, and medicine. Unfortunately, there are still many aspects of FE analysis that need to be studied in order for this technique to more effectively support biomedical research. The current study examines how material property variation influences FE data to further advance FE analysis and augment biomedical data validity. Using standardized segmentation, 3D anatomical models of whole femur structure were obtained from cadaveric CT data provided by the University at Buffalo Anatomical Gift Program. FE analysis of the model experimental groups with different elastic properties was carried out simulating physiological loading of the femur consistent with previous biomechanical experiments on the femur model system. The results revealed that minor changes in material properties of FE models yield statistically significant differences in maximum displacement, average displacement, and average strain. Regional strain disparities were especially prominent at the inferior femoral neck, medial aspect of the femoral shaft, and the distolateral femur. The results indicate that Young’s modulus variation that is smaller than the variation in Young’s modulus values between FE studies leads to significant differences in biomechanical data. Therefore, these findings underscore the necessity for careful selection of exact elastic properties that are informed by validation data when feasible and consistent for particular anatomical structures across studies in order to advance FE modeling in biomedical research.

Finite Element and Experimental Modal Analysis of Car Roof with and without damper

A practical piezoelectric vibration energy harvesting (PVEH) system is usually composed of two coupled parts: a harvesting structure and an interface circuit. Thus, it is much necessary to build system-level coupled models for analyzing PVEH systems, so that the whole PVEH system can be optimized to obtain a high overall efficiency. In this paper, two classes of coupled models are proposed by joint finite element and circuit analysis. The first one is to integrate the equivalent circuit model of the harvesting structure with the interface circuit and the second one is to integrate the equivalent electrical impedance of the interface circuit into the finite element model of the harvesting structure. Then equivalent circuit model parameters of the harvesting structure are estimated by finite element analysis and the equivalent electrical impedance of the interface circuit is derived by circuit analysis. In the end, simulations are done to validate and compare the proposed two classes of system-level coupled models. The results demonstrate that harvested powers from the two classes of coupled models approximate to theoretic values. Thus, the proposed coupled models can be used for system-level optimizations in engineering applications.