Characteristic analysis and experimental evaluation of artificial pneumatic cylinder

The fluidic muscle cylinder consists of an air bellows tube, flanges and lock nuts. Its features are softness of material and motion, simplicity of structure, low production cost and high power efficiency. Recently, unlike the pneumatic cylinder, the fluidic muscle cylinder without air leakage, stick slip, friction or seals was developed as a new concept actuator. It has characteristics such as light weight, low price, high response, durable design, long life, high power and high contraction. In this study, we carried out finite element modeling and analysis on the main design variables such as contraction ratio and force, and diameter increment of the fluidic muscle cylinder. On the basis of finite element analysis, the prototype fluidic muscle cylinder was fabricated and tested. Finally, we compared the test results with the finite element analysis.

PurposeWe aimed to determine if finite element analysis (FEA) provides useful thresholds for bone biopsy practice patterns.MethodsThe femoral head compression test was performed on rabbit femurs, using FEA to identify the part of the bone that preferentially fractures (n=15/group). Four types of rectangular biopsy holes were made using finite element (FE) models. These models were divided into control (no defect), defect 1 (10% width), defect 2 (20% width), defect 3 (30% width), and defect 4 (40% width) groups (n=15 each). Three types of rectangular biopsy holes (defect A, 27% length; defect B, 40% length; defect C, 53% length) were also made using FE models (n=15 each). The load to failure was then predicted using FEA.ResultsAlmost all femurs with no defect were fractured at the femoral shaft in both the femoral head compression test and FEA. The experimental load to failure in intact femurs was predicted well by the FE models (R2=0.74, p<0.001). There was also a strong linear correlation of stiffness between compression test in femurs with no defect and the FEA (R2=0.68, p<0.001). Therefore, the femoral shaft was targeted for FEA. The median predicted loads by FEA were significantly higher for defect 1 than for the other types when testing the widths of the rectangular defects, but there were no significant differences among the three types when testing for defect length.ConclusionThe FEA results correlated well with those of the femoral head compression test. A width <10% of the circumference length in bone biopsy holes helps minimize bone strength reduction using FEA. It may be useful for orthopedic doctors to perform FEA to avoid pathological fractures after bone tumor biopsy.

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

The present study aimed to identify the optimal design of the unicompartmental femoral component through parameter analysis and stability evaluation. A finite element (FE) analysis was applied to analyse and adjust the parameter combinations of the anterior tilt angle of the posterior condyle resection surface, the position of the peg, the length of the pegand the inclination angle of the peg, resulting in 10 different FE models. Setting three knee flexion angles of 8.4° (maximum load state during walking), 40° (maximum load state during stair climbing)and 90° (maximum load state during squatting exercise), quantitatively analysing the micromotion values of the bone-prosthesis interfaceand defining a weighted scoring formula to evaluate the stability of different FE models. The validity of the FE analysis was verified using the Digital Image Correlation (DIC) device. The errors between the FE analysis and the DIC test at three flexion angles were 5.6%, 1.7%and 11.1%. The 10 different femoral component design models were measured separately. The FE analysis demonstrated that the design with a 0° anterior tilt angle of the posterior condyle resection surface, both pegs placed on the distal resection surface, lengthened 5 mm pegsand a 10° peg inclination angle provided the best stability. The current study proposed a method for evaluating the stability of the femoral component design. The optimal intersurface stability design of the unicompartmental femoral component was achieved with two pegs placed on the distal resection surface, a 5-mm peg length incrementand a 10° peg inclination. These results might provide a reference for the selection of unicompartmental femoral components in clinical practice and therefore improve the survival rate of future unicompartmental knee arthroplasty. Level III.

During a seismic event, first-story end columns in steel Special Moment Frames (SMFs) experience ‎lateral drift demands combined with high levels of axial load due to gravity loading and dynamic ‎overturning moment effects. Deep slender wide-flange sections are typically assigned for the ‎seismic design of perimeter SMFs in North America. The flange and web of these sections have ‎high slenderness ratios, just below the compactness limits specified by AISC 360-10. This makes ‎these sections vulnerable to local and lateral torsional buckling failure modes. ‎ In this paper, the cyclic behavior of deep slender wide-flange steel beam-columns, under combined ‎lateral drift and axial load, is investigated through detailed finite element analysis (FEA). The main ‎design variables that are considered as part of the FEA investigation are (a) the section slenderness; ‎‎(b) the lateral loading protocol; and (c) the axial load level. Emphasis is placed on the effect of ‎these variables on (a) the cyclic deterioration in flexural strength; (b) the column axial shortening; ‎and (c) the lateral torsional buckling of the steel beam-columns. To this end, a range of deep ‎slender wide-flange sections, commonly found in low to mid-rise SMFs, is selected. Two lateral ‎loading protocols are used: 1) a symmetric protocol and 2) a near fault protocol. The axial load is ‎applied in two forms: 1) constant compressive load; and 2) cyclic axial load varying from ‎compression to ‎tension. The latter represents the variation in the axial load experienced by an end ‎column due to the dynamic overturning ‎moments during an earthquake. Using a validated FEA ‎modeling approach, typical first-story end columns of prototype steel SMFs are modeled and ‎analyzed under the aforementioned-coupled lateral and axial loading protocols. The boundary ‎conditions at the base of the columns are fixed. At the top of the columns the flexibility associated ‎with the corresponding exterior beam-to-column connection is considered. Lateral braces are also ‎provided to the column, as per the design code requirements.‎ The FEA simulations demonstrated that higher rates of cyclic ‎deterioration in flexural strength are ‎associated with sections with larger web slenderness, due to severe web local buckling. Sections ‎with large web and flange slenderness ratios also suffer from higher axial shortening levels at lower ‎story drifts compared to more compact sections. It is also concluded that deep slender wide-flange ‎sections with lower resistance to out-of-plane and torsional force demands, experience higher ‎twisting and are likely to be subjected to lateral torsional buckling. The study also shows that axial ‎force demands on the column’s lateral braces exceed their code design capacity at relatively low ‎story drift ratios. Furthermore, the location of the column inflection point and the associated ‎column moment gradient is monitored during the finite element analysis in order to assess the ‎potential of plastic hinge formation at the top of the column once plastification and cyclic ‎deterioration in flexural strength of the column occurs at its base. This is a critical issue since it ‎could potentially lead to weak-story collapse mechanisms.‎

A finite element based method for estimating natural frequencies of locally damaged homogeneous beams

Correlation between Injury Pattern and Finite Element Analysis in Biomechanical Reconstructions of Traumatic Brain Injuries

The vibrational effect is one of the primary considerations during construction due to the ambient excitation from the surrounding environment. Thus, it is necessary to find the most dependable Finite Element (FE) model for the actual structure to improve its quality and life span on site. In this context, the study included a 3-story building model that was analyzed using finite element analysis to determine its dynamic properties such as natural frequency and mode shape to avoid the resonance effect. It is due to the importance of obtaining a reliable and accurate model by verifying with the results of the Operational Modal Analysis (OMA). In general, the goal of this study is to update the FE model so that it is close to the actual scaled model based on the previous OMA study. As a result, an initial linear FE model of the 3-story building scaled model was created using CAD software based on actual geometry to describe the structure's physical properties. The FE model was then imported into CAE software, where the boundary condition and estimated material properties were assigned to determine the effect of random vibration. Through the pairing of Finite Element Analysis results and previous studies, 9 natural frequencies and 9 mode shapes were extracted. The Modal Assurance Criterion (MAC) was used to compare the mode shape of FE results against the OMA to determine the degree of consistency between paired mode shapes. A model updating process was carried out to reduce the discrepancy between the methods. The uncertainties arising from the initial conditions have been discussed in terms of the stiffness of the material used. The updated model allows for an evaluation of the structure's current actions as well as the development of models for a wide range of potential future research scenarios.

In this paper, the finite element analysis (FEA) for a proposed secondary containment assembly (Envirolock) intended to protect the environment from pipelines leaks was carried out. The assembly, composed from a Fiber Reinforced Polymer (FRP), aims to protect the most susceptible locations on pipelines where corrosion, dents and cracks could cause pipeline leaks to occur. The FEA was conducted to investigate the mechanical capacity of the system under hoop and longitudinal pressures. In the current study, the system was under full pressure emanating from a leak from the carrier pipe into the secondary containment liner. To explore the resistance capability of the containment system, which is composed of three layers (two polyurea and one carbon fiber), against internal pressure, finite element models were developed. Two separate finite element models for mid-pipe and end cap segments were created. System failure was defined as material failure, where failure pressure being the pressure at the onset of material failure in any layer. The FEA results indicated that the strength and failure of the mid-pipe segment under internal pressure is dominantly controlled by the carbon fiber layer. The failure of this layer will consequently lead to the failure of the polyurea layers. The carbon fiber makes the system capable of sustaining internal pressure (hoop stresses) up to 86 MPa. For the end cap FEA model, several consecutive trials and modifications were prototyped, and finite element models were created accordingly. The final design of the end cap has a cone-shaped geometry that is reinforced by different numbers and directions (acting in hoop and longitudinal directions), of carbon fiber layers wound over the surface of the end cap assembly. Based on the FEA results, the end cap segment of the containment system can sustain internal pressure of 21.5 MPa to 27 MPa depending on the number of CF layers. These results indicated that the containment system is safe to be used for most operating pressures of liquid and gas pipelines without compromising the assembly. The results of this FEA were used to finalize the design. The system passed ASME PPC-2 certification testing, the results of which can be used to finetune these FEA models. As more stringent rules and government regulations are enacted to enhance the protection of the environment, pipeline operators need to be proactive regarding public safety and the protection of the environment from pipeline leaks. This system is a risk mitigation tool containing pipeline leaks until further actions are implemented by pipeline operators. It also has the advantage of being a low-cost solution that can be installed on new or existing pipelines.

Modal analysis is an approach to determine the dynamic behavior of a structure through numerical analysis or experimental approach. Nowadays, numerical analysis has been preferred by most researchers and engineers compared to experimental analysis to analyze the structure due to expenditure and time consuming factors of the research. Recently, numerical analysis is done computationally or well known as Finite Element Analysis (FEA) by using finite element (FE) model to replicate the real test structure. Instead of advantage of FE analysis, the trustworthiness of FE model has been questioned since simplification has been made during design stage for complex structure and inaccurate of geometry input of the model. Hence, this paper is carried out to reduce the discrepancies between numerical prediction results with measured test data on FE model of exhaust structure by implementing FE model updating using SOL200 algorithm. Initially, the FE model is running on normal mode analysis SOL103 to extract the modal parameters such as natural frequency and mode shape. Then, the numerical pre-diction result has been correlated and validated with measured test data obtained through Experimental Modal Analysis (EMA). Due to disagreement between numerical result and experimental data in correlation process, the FE model has been updated using SOL200 algorithm. The percentage error between numerical prediction result and measured test data is minimized from 5.67 to 3.23% after been updated. It’s shown the capability SOL200 algorithm in preparing the reliable FE model before been used for further analysis such as structural dynamic modification.KeywordsDynamic studyJoints strategyFinite element analysisExperimental modal analysisFE model updating

The introduction of Intelligent Robot Service is the direction of library development. The application of intelligent robot technology will greatly improve the library service efficiency and service level. At present, there are still some problems in library service of intelligent robot, such as the core technology needs to be mastered skillfully, the level of intelligent service is not enough, and the construction of Corpus needs to be improved. In the era of library intelligent service, intelligent robot should pay more attention to the application of multi-purpose intelligent robot system in library, the fusion of Intelligent Library and robot technology under the background of Internet of things, and the development trend of intelligent robot providing various care services for different readers. The introduction of intelligent robot technology will greatly improve the efficiency of books on and off shelves, and expand the space-time limit of reference service. In the process of building the intelligent library, the infrastructure and service of the traditional library are reconstructed by using the automatic book access robot and the Consulting robot system, it can be concluded that Book Auto-access Technology and IM consultation system are most suitable for library management system, and Book auto-access robot technology can solve the bottleneck problem of library intelligent robot technology, promoting the transformation and upgrading of libraries to smart libraries.

Computational evaluation of the axis-blade angle for measurements of implant positions in trochanteric hip fractures: A finite element analysis

Typically, axial flux permanent magnet machines require 3-dimensional (3D) finite element analysis, increasing the amount of time required to complete a machine design. To overcome the drawback of 3D finite element analysis, several authors have proposed 2-dimensional (2D) finite element (FE) modeling and analysis techniques. This paper expands upon previous work, investigating quasi-boundary conditions to address end-effects and expands upon existing knowledge of discretizing the 3D problem into multiple 2D models for axial flux permanent magnet (AFPM) machines. The results of 2D finite element method are verified by a prototype which has single rotor, dual stator (SRDS) configuration. The results presented in this paper reaffirm that the less conventional SRDS AFPM can be effectively modeled in 2D, and that quasi-boundary condition can offer increased model accuracy, relative to conventional 2D FE modeling of AFPM machines.

This work is a vital step in enhancing the potential use of a newly developed organic basalt fibre reinforced polymer (BFRP) bars for prestressed concrete applications. In the present study, a test setup has been designed using finite element analysis (FEA) and the various steps of prestressing such as initial prestress, effective prestress and the time dependent effects have been appropriately simulated in the finite element (FE) model. The configuration details of the test setup, such as the size and orientation of the sections and the location of the stiffener plates have been thoroughly investigated. A robust design of the setup has been established based on the FEA results. Subsequently, the FE model has been utilized to predict the transfer stage parameters for concrete beams prestressed using BFRP bars.The transfer length has been predicted from the FEA results to be 24db and 26db (where, db is the diameter of bar) when measured using the BFRP bar strains and the concrete strains, respectively. An end slip of 0.3mm has been obtained after the prestressing of concrete beams. The designed test setup will be later fabricated and utilized to perform experiments under laboratory-controlled conditions.

Understanding and prediction of physical phenomena in different scales at the same time that are taking place at the tool/workpiece interface during high shear processing is done in different ways combining the latest finite element (FE) and discrete element (DE) analysis technology. The high shear processing is observed during hot rolling of aluminium, when it produces a highly deformed subsurface layer; and also during friction stir welding (FSW), when it results in significant heat generation and flow. The FE analysis is used for macro-scale simulation while the DE method is applied to simulate meso-scale phenomena taking place in the thin, sometimes a few micron thicknesses, surface layer. Different FE models and numerical techniques combined with DE based transient dynamics approaches are discussed in this work.