Determining parameters of peat soil for finite-element analysis using the Cam Clay model

A bioengineering course is offered to senior students in the Mechanical Engineering major as an elective at Penn State Behrend in the first semester of their senior year. On average around 20 students enroll in this project-based course and 72% of their grade depends on three comprehensive group projects, one of which is to design a bone plate for a fractured femur. 6% of the grade comes from an individual application presentation, discussing different circumstances in which the concepts in mechanical engineering can be applied to solve/analyze biomedical problems. Background of physiology is introduced in the class while the majority of applicable engineering knowledge was learned in prerequisite courses, such as statics, dynamics, strength of materials, system dynamics, etc. Finite Element Analysis (FEA), an elective offered in both semesters of senior year, is not a prerequisite for this bioengineering course. Most of students enrolled in our bioengineering course either do not have FEA course or are taking FEA concurrently. Therefore in spite of its popularity in the areas related to biomechanics, thus far FEA has not been incorporated in this bioengineering course. Previously, the fractured femur project utilized the applicable theoretical analyses including those from statics, strength of materials, materials, and machine design. In Fall 2015, the instructor of bioengineering course made an effort to have an FEA study on femur and ensuing presentation be completed by a willing student. This student was taking FEA simultaneously with bioengineering, and was scheduled to present during the last week of semester. The instructor of FEA wrote an introductory manual of FEA procedures to analyze a healthy femur using a CAD model of the femur. Then the student used the manual to initiate the FEA study of the fractured femur. A major challenge to the student was the complicated loading and assembly feature of the bone plus the addition of bone plate. After a several week struggle and independent learning, while guided by the faculty members of bioengineering and FEA, the student was able to accomplish the FEA analysis and presented the results to the class. The discrepancy between FEA results and theoretical analysis was shown to be less than 5% in most results. The presentation also included FEA results for a diverse realistic loading and boundary conditions. Since all students had finished the fractured femur project, they actively participated in a meaningful discussion after the presentation. The completion of this project demonstrated the feasibility and importance of incorporating FEA in our bioengineering course. In addition, the presenting student was able to complete a working manual for the FEA analysis of the fractured femur, which can be passed to the future students of this course. A plan is to include FEA in the project as a bonus activity, and regarding the formation of project teams, the instructor would appoint a member who is enrolled in the FEA course. An assignment or project, based on the present FEA study of the femur, can also be incorporated in the FEA course offered at our campus.

This paper evaluates the performance of a Three-phase Asynchronous Generator (TAG) with Dual Stator-Winding (DSW) as a potential candidate for large aircrafts variable frequency AC power generating systems. One of the stator windings is used to provide the necessary Capacitive Excitation (CE) for voltage generation in the second winding (armature). The use of a DSW and CE permits also the generation of voltage at subsynchronous speeds, as it is not the case in conventional TAG that requires voltage build up at speed above synchronism. The variable frequency can be obtained by generating the AC voltage from lower to very high speed for different capacitance excitation values. The performance evaluation is done through Finite Element Analysis (FEA) and Experimental Measurement (ExPM). From both FEA and ExPM results, it is evident that the TAG with DSW has the capability to generate AC voltages with positive, zero and negative slips. The FEA results also proved that the effect of armature reaction does not contribute significantly to the distortion of the generated voltage for both resistive (unity power factor) and inductive (lagging power factor) load currents.

In order to obtain information on the lateral buckling strength of stainless steel I-beams to propose the design formulae for the stability factors, this paper focuses on the overall buckling of laterally-unrestrained stainless steel I-beams. The design methods in current codes are discussed, and the results from these codes are compared with the finite element analysis (FEA) results. The influence from the material property on the overall stability of stainless steel beams is also investigated. Based on the FEA results, the design method on overall buckling strength of steel beams specified in the Chinese standard GB 50017-2003 is modified to calibrate the overall stability of stainless steel bending members with welded I-section. Through the comparison with EC3: 1993-1-4 and the FEA results, the proposed formulae in this paper are proved to be applicable in the design of overall stability of stainless steel bending members.

Seismic performance of a square HSS column to H-section beam bolted connection with double cover plate

The transverse impact responses of 3-D braided composite I-beam

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.

Failure assessment of fiber metal laminates based on metal layer dispersion under dynamic loading scenario

An analytical method is presented to analyze the effect of thermal deformations of an optical pick-up base on the optical properties of DVD optical system. To measure the amount of thermal deformations of an optical pick-up base, finite element analysis and holographic interferometry were used. First, thermal deformations of an aluminum pick-up base was analyzed in thermal environments using finite element analysis; finite element analysis was carried out without the initial surface stress condition. The measurement of thermal deformations by holographic interferometry was carried out to verify finite element analysis results. However, since the finite element analysis results were deviated from those by experiment, the effect of the initial surface stress condition was considered; finite element analysis was carried out with the initial surface residual stress condition, which was obtained from X-ray diffraction measurement. The finite element analysis results with the initial surface stress condition agreed well with the experimental results by holographic interferometry. Finally, to analyze the effect of thermal deformations of the pick-up base on the optical properties of DVD optical system, the deformation of optical path was analyzed. However, the drastic changes of beam spot, beam intensity profile, modulation transfer function curve and wavefront aberration were not observed.

Elastic-plastic analysis of a nozzle corner crack by finite element method

Elastic-plastic FEM-analysis of a nozzle corner crack and discussion of the results by some fracture mechanics concepts

This paper presents an application of finite-element analysis to deep excavation in layered sandy and clayey soil deposits using a combination of the hyperbolic and the Modified Cam-clay models. In the analysis, the drained behavior of cohesionless soil and the undrained behavior of cohesive soil were simulated using the hyperbolic and Modified Cam-clay models, respectively. A rational procedure for determining soil parameters for each of the models was established. A simulation of the dewatering process during excavation was proposed. The analytical procedure was confirmed through an analysis of three actual excavation cases. Finally, analyses considering pore-water pressure dissipation during the actual elapsed time for each construction phase were carried out. The results indicate that the calculated displacement of a retaining wall during excavation is smaller than that given by undrained analysis. It was thought that some degree of pore-water pressure dissipation actually occurs during the intermediate excavation stages. This results in a decrease in the final deformation of the wall and ground.-surface settlement than would be predicted by undrained analysis. Key words : finite-element analysis, deep excavation, hyperbolic model, Cam-clay model.

Dynamic characteristics and reliability of elastomeric pads are dominant components in the design methodology to satisfy the performance parameters under dynamic operations. The fatigue life of rubber pads fitted with elastomeric pads mainly depends upon elastomers; natural rubber, chloroprene, nitrile butadiene, silicon compounds, etc., additives, accelerators, activators, fillers, anti-degradants, and manufacturing processes. The performance of the elastomeric pad is evaluated based on service operation, simulation, and laboratory testing. New and failed elastomeric (EM) pads have been examined in the Indian Rubber Manufacturer’s Research Association IRMRA laboratory for detailed failure analysis of existing EM pads. Further, chemical and physical properties are also evaluated in M&C (Metallurgical and Chemical) and Testing Directorate of Research Designs and Standards Organization (RDSO), labs respectively. The fatigue life of the EM pad is estimated based on the results extracted from the Finite Element (FE) analysis of the EM pad. An attempt is made to modify the design of the EM pad by considering the results of detailed field trials, lab testing, and FE analysis. The modified design satisfies the dynamic characteristic during FE (Structural and Thermal) analysis and lab testing.

Modeling and FEA (finite element analysis) are required to be done over again after changing the key parameters. Thus, this paper constructs a distributed system which can change parameters of product, model and do FEA automatically. And it obtains the optimizing parameters at last. This system running on intranet bases on genetic algorithm and CATIA/CAA. Every client reads key parameters from the database in the server, drives the CATIA three-dimensional model by CATIA/CAA and the key parameters, and does FEA. After the result of FEA was sent to the database, the server evaluates the result of FEA and sends the evaluation to the database. Then, the server creates new key parameters using genetic algorithm; the system goes to next circle. The parameters, whose evaluation is the best, are the last result. Based on this system, the self-optimizing of key parameters for TBM (tunnel boring machine) is realized and accelerates the design process

Finite element analyses on transverse impact behaviors of 3-D circular braided composite tubes with different braiding angles

High magnetic field strength and high-speed gradient coil current switching are becoming ever more commonplace in magnetic resonance imaging scanners. These and other factors are combining to yield high acoustic sound pressure levels (SPLs) in and around magnetic resonance imagers. Studies have already been conducted which partially characterize this sound field, and various methods have been investigated to attenuate the noise generated. In order to predict the vibration and acoustic response of a gradient coil inside a scanner, finite element analysis (FEA) was carried out. The model was based on specific internal and external structural dimensions and the material physical properties of a gradient coil. The FEA results were verified through experimental modal testing of the same gradient coil. It was found that the experimental modal analysis results were in good agreement with the FEA results. The Lorentz force distribution on the gradient coil caused by the time varying current in the coil windings was then applied to the FEA model to obtain the velocity distribution of the coil surface as a function of time. A vibro-acoustic computational model was then developed based on the verified FEA model. The surface velocity distribution was then used to predict the sound field inside the gradient coil. The vibro-acoustic model was verified using experimental noise measurements with swept sinusoidal waveform inputs to the gradient coil conductors. The numerical methods developed in this study could provide a guide and virtual testing platform for the designer of gradient coils to predict the vibration and acoustic behavior of new designs and thereby offer the opportunity to redesign and/or optimize the design to reduce SPLs.