TRIMMING LINE DESIGN USING AN INCREMENTAL DEVELOPMENT METHOD AND A FINITE ELEMENT INVERSE METHOD

In most of automobile body panel manufacturing, trimming process is generally performed before flanging. To find feasible trimming line is crucial in obtaining accurate edge profile after flanging. Section-based method develops blank along manually chosen section planes and find trimming line by generating loop of end points. This method suffers from inaccurate results of edge profile. On the other hand, simulation-based method can produce more accurate trimming line by iterative strategy. In this study, new fast simulation-based method to find feasible trimming line is proposed. Finite element inverse method is used to analyze the flanging process because final shape after flanging can be explicitly defined and most of strain paths are simple in flanging. In utilizing finite element inverse method, the main obstacle is the initial guess generation for general mesh. Robust initial guess generation method is developed to handle genera] mesh with very different size and undercut. The new method develops final triangular mesh incrementally onto the drawing tool surface. Also in order to remedy mesh distortion during development, energy minimization technique is utilized. Trimming line is extracted from the outer boundary after finite element inverse method simulation. This method has many advantages since trimming line can be obtained in the early design stage. The developed method is verified by shrink/stretch flange forming and successfully applied to the complex industrial applications such as door outer flanging process.

Shape sensing for thin-shell spaceborne antennas with adaptive isogeometric analysis and inverse finite element method

Reactive synthesis is an automated procedure to obtain a correct-by-construction reactive system from its temporal logic specification. Despite significant research progress in the past decades, reactive synthesis is still in early-stage of use. Previous studies found that the lack of development methods for reactive synthesis specifications is one barrier to its wider adoption. In this paper, we adapt two development methods, an incremental method and a modular method, to the context of reactive synthesis specifications. The methods are based on existing software development methods on the one hand and studies about reactive synthesis on the other hand. Then, we report on an exploratory case study in which participants developed specifications using the two methods. We evaluated the methods using a mixed-method analysis that combines grounded theory analysis of Slack communication with participants, quantitative exploratory data analysis of the synthesis IDE usage logs, and qualitative independent expert review of the final specifications. Our findings show clear benefits of modular specification development in terms of ease of planning, synthesis time, fewer unrealizability issues, and faster debugging. However, the incremental development method was more natural and easy to use, and specifications developed incrementally were also easier to validate during the development process.

An effective calibration method based on fuzzy network for enhancing the accuracy of inverse finite element method

This chapter describes a pragmatic approach to using open source and free software tools as valuable resources to affect learning of software industry practices using iterative and incremental development methods. The authors discuss how the above resources are used in teaching undergraduate Software Engineering (SE) courses. More specifically, they illustrate iterative and incremental development, documenting software requirements, version control and source code management, coding standards compliance, design visualization, software testing, software metrics, release deliverables, software engineering ethics, and professional practices. The authors also present how they positioned the activities of this course to qualify it for writing intensive designation. End of semester course evaluations and anecdotal evidence indicate that the proposed approach is effective in educating students in software industry practices.

To become more reactive and flexible to the market needs, i.e. shorter lead-times and more flexibility in handling late and changing requirements, Ericsson’s AXE 10 development processes have been adapted to support incremental development. The basic principle is to develop each of the customer features in one executable and testable increment. In order to plan, coordinate and control projects executed in this way, an Incremental Development Method Package, IDMP, has been developed by UAB in close cooperation with support groups in development projects. In this paper, we define what we mean with incremental development and describe the main aspects of the package. We also report experiences from using the package in the CMS 30 phase 7 and HELIOS projects. A prototype tool which supports the package is described, together with the experiences from using the tool in the pilot project Combined Gateway. Even if the IDMP has been developed towards AXE 10, it has proven useful in non AXE 10 projects, as the principles are rather independent of development process.

To become more reactive and flexible to the market needs, i.e. shorter lead-times and more flexibility in handling late and changing requirements, Ericsson’s AXE 10 development processes have been adapted to support incremental development. The basic principle is to develop each of the customer features in one executable and testable increment. In order to plan, coordinate and control projects executed in this way, an Incremental Development Method Package, IDMP, has been developed by UAB in close cooperation with support groups in development projects. In this paper, we define what we mean with incremental development and describe the main aspects of the package. We also report experiences from using the package in the CMS 30 phase 7 and HELIOS projects. A prototype tool which supports the package is described, together with the experiences from using the tool in the pilot project Combined Gateway. Even if the IDMP has been developed towards AXE 10, it has proven useful in non AXE 10 projects, as the principles are rather independent of development process.

In preclinical radio-neuromodulation research, small animal experiments are pivotal for unraveling radiobiological mechanism, investigating prescription and planning techniques, and assessing treatment effects and toxicities. However, the target size inside a rat brain is typically in the order of sub-millimeters. The small target inside the visual cortex neural region in rat brain with a diameter of around 1mm was focused in this work to observe the physiological change of this region. Delivering uniform doses to the small target while sparing health tissues is challenging. Focused kV x-ray technique based on modern x-ray polycapillary focusing lens is a promising modality for small animal radio-neuromodulation. The current manual planning method could lead to sub-optimal plans, and the positioning uncertainties due to mechanical accuracy limitations, animal immobilization, and robotic arm motion are not considered. This work aims to design a robust inverse planning method to optimize the intensities of focused kV x-ray beams located in beam trajectories to irradiate small mm-sized targets in rat brains for radio-neuromodulation. Focused kV x-ray beams were generated through polycapillary x-ray focusing lenses on achieving small (≤0.3mm) focus perpendicular to the beam. The beam trajectories were manually designed in 3D space in scanning-while-rotating mode. Geant4 Monte Carlo (MC) simulation generated a dose calculation matrix for each focused kV x-ray beam located in beam trajectories. In the proposed robust inverse planning method, an objective function combining a voxel-wise stochastic programming approach and L1 norm regularization was established to overcome the positioning uncertainties and obtain a high-quality plan. The fast iterative shrinkage thresholding algorithm (FISTA) was utilized to solve the objective function and obtain the optimal intensities. Four cases were employed to validate the feasibility and effectiveness of the proposed method. The manual and non-robust inverse planning methods were also implemented for comparison. The proposed robust inverse planning method achieved superior dose homogeneity and higher robustness against positioning uncertainties. On average, the clinical target volume (CTV) homogeneity index (HI) of robust inverse plan improved to 13.3 from 22.9 in non-robust inverse plan and 53.8 in manual plan if positioning uncertainties were also present. The average bandwidth at D90 was reduced by 6.5Gy in the robust inverse plan, compared to 9.6Gy in non-robust inverse plan and 12.5Gy in manual plan. The average bandwidth at D80 was reduced by 3.4Gy in robust inverse plan, compared to 5.5Gy in non-robust inverse plan and 8.5Gy in manual plan. Moreover, the dose delivery time of manual plan was reduced by an average reduction of 54.7% with robust inverse plan and 29.0% with non-robust inverse plan. Compared to manual and non-robust inverse planning methods, the robust inverse planning method improved the dose homogeneity and delivery efficiency and was resistant to the uncertainties, which are crucial for radio-neuromodulation utilizing focused kV x-rays.

<abstract> <bold>Abstract.</bold> Pressure-compensating (PC) emitters can maintain a constant discharge within a wide range of working pressures, thus they have extensive application prospect in mountain regions where the hydraulic pressure in irrigation systems often changes greatly. Although the rapid design method for non-PC emitters based on CFD is quite mature at present, common CFD method is not suitable for the design of PC emitters because there exists a two-way coupling interaction between the fluid flow and elastic diaphragm. In order to improve the design accuracy and efficiency of PC emitters, the fluid-structure interaction (FSI) analysis was studied in this paper. In the FSI analysis procedure, adaptive mesh repair was adopted to refine the distorted fluid mesh. Incremental method and displacement-pressure finite element formula were used for the nonlinear analysis of the incompressible material. In this paper, SST K-ω turbulence model was used for the fluid analysis, while contact analysis method and Neo-Hookean Mooney-Rivlin rubber material model were adopted for the structure analysis. The results showed that the discharge was adjusted by a very small deformation of the diaphragm to reach a steady state. At last, compared with the test results carried out using the test samples made by rapid prototyping, the analyzed values were a little larger while the maximum relative deviation was within 2.5%. This verified that PC emitter's discharge could be predicted by FSI analysis accurately. In conclusion, FSI analysis is an efficient way to improve the design accuracy and reduce the test times for PC emitters.

The aim of this PhD thesis is to extend the capability of the contour method for residual stress measurement in metallic components by resolving two of its main limitations. The contour method involves sectioning a body into two equal parts that have mirror-symmetric geometry, stiffness and residual stress field. The deformations of the cut surfaces introduced by sectioning are then measured. These raw measured data are processed using filtering and smoothing techniques. The last step involves back calculating the residual stress distribution acting out of the cut plane that has been relaxed. This is equal to the original residual stress present at the cut plane before the body was cut. A major limitation of the contour technique is that it is strictly only applicable to flat cuts along a symmetry plane of a body. Another fundamental assumption in the contour method is that residual stresses re-distribute elastically during the sectioning cut. However, this assumption can be violated if the residual stress magnitude is close to the material yield strength value and lead to plasticity cutting induced errors in the contour method results. Thus another major limitation of the technique is the risk of cutting induced plasticity that can introduce significant stress measurement errors. This PhD thesis contributes to knowledge in the field through first presenting a novel contour data analysis approach for the more general case of sectioning at an arbitrary plane where the cut parts do not possess mirror-symmetry. This greatly extends the types of structure, and the volume of material within structures, where residual stresses can be measured using the contour method. The second contribution to knowledge is the invention of an incremental contour measurement method involving multiple cuts. This new approach can be applied to sequentially reduce residual stresses in the structure of interest and thereby lower or eliminate the risk of inducing plasticity during cutting and reduce consequent measurement errors. Both new approaches proposed in this PhD thesis are successfully demonstrated through numerical simulation using the finite element method and experimentally on benchmark steel specimens and against neutron diffraction measurements.

Objective To explore the effect of laparoscopic transabdominal preperitoneal hernia repair (TAPP) with 3D mesh on the pain degree and postoperative recurrence of inguinal hernia. Methods Seventy patients with inguinal hernia who underwent surgery in the First Affiliated hospital of Xinjiang Medical University from September 2016 to December 2017 were divided into the 3D mesh group (n=35) and the ordinary mesh group (n=35) according to the different meshes used during surgery. All patients were treated with TAPP. Among them, the mesh used in the 3D group was Bard-3DMAX hernia mesh, while the mesh used in the ordinary mesh group was Covidien (Tyco) hernia mesh. The operation indexes, postoperative pain visual analog scale (VAS), complications and recurrence of the two groups were observed and compared. Results There were no significant differences in operation time, hospital stay and intraoperative bleeding between the two groups (P>0.05). The operation-related expenses and the time of getting out of bed after operation in the 3D group were less than those in the ordinary mesh group (P 0.05). The score of VAS in the 3D group was lower than that in the ordinary mesh group at 24 hours, 72 hours, 7 days and 15 days after operation (P 0.05). Conclusion TAPP is a safe and effective surgical method. The use of 3D mesh can simplify the operation, reduce the postoperative pain of patients, and has reliable curative effect. It is worthy of clinical application. Key words: 3D mesh; Transabdominal preperitoneal prosthesis; Hernia, inguinal; Surgical indexes; Postoperative pain

As VLSI techniques are getting more and more advanced, the size of the power grid network increases dramatically. Therefore, the power grid analysis becomes a challenging task during the design procedure. This work utilizes the macromodeling technique [1] and enhances the Orthogonal Matching Pursuit (OMP) based method [2] to develop an effective and robust incremental analysis method for the power grid network, MA-OMP <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sup> . Given a power grid network, MA-OMP <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sup> not only can deal with the change of its element values but also can handle the modification of its topology. The experimental results show that MA-OMP <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sup> can be an order of magnitude faster than the OMP-based method [2] which can only deal with the change of element values of the power grid. The experimental results also demonstrate that MA-OMP <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sup> can accurately and efficiently handle the modified topology of the power grid network.

A general and consistent hybrid non-linear finite element/boundary element method is developed for the purpose of modeling the deformations in an elastic structure under the action of electrostatic forces. Problems of this type occur frequently in the analysis and design of microelectromechanical systems (MEMS) in which electrostatic actuation is used. Numerous MEMS structures, such as spatial light modulators, deformable micromirrors, and microvalves, have been developed in recent years which use an electrostatic actuation scheme. Because of the highly non-linear nature of the electroelastic behavior of these systems, the process of designing such structures requires a general and powerful numerical technique. An incremental non-linear finite element method is formulated which uses a boundary element solution at each load step to update the electrostatic force on the body and the simple example of a deformable diaphragm is investigated.

The authors put forward a procedure of creep analysis for variable loading conditions, which involves the use of the incremental creep theory and finite element method. Variable loading with load increase and relief at a constant temperature is considered as a stepwise process. The authors study a growth of deflections and stress relaxation in a intermediate-cylinder diaphragm of a steam turbine in various loading modes as well as special features of residual stress distribution in fixed blades.

The life expectancy of a solid component is traditionally predicted by assessing its expected stress cycle and comparing it to experimentally determined stress states at failure. The accuracy of this procedure is often compromised by unforeseen extremes in the loading cycle or material degradation. Residually stressed parts may either have longer or shorter lifespans than predicted. Thus, determination of the current state of stress (i.e., the residual stress in the absence of external loading) and material properties is particularly important. Typically, the material properties of a solid are determined by fitting experimental data obtained from the measured deformation response in the stress-free configuration. However, the characterization of the mechanical behavior of a residually stressed body requires, in principle, a method that is not restricted to specific constitutive models. Complementing a recently developed technique, known as the reversed updated Lagrangian finite element method (RULFEM), a new method called estimating the current state of stress (ECSS) is presented herein. ECSS is based on three-dimensional full-field displacement and force data of a body perturbed by small displacements and complements the first step of the incremental RULFEM method. The present method generates the current state of stress (or residual stress in the absence of external tractions) and the incremental elasticity tensor of each finite element used to discretize the deformable body. The validity of the ECSS method is demonstrated by two noise-free simulation cases.