bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the Size-Dependent Static and Dynamic Behavior of Circular Micro-Plates Subjected to Capillary Force
Authors: Kahrobaiyan M. H. , Vardi I. , Ahmadian M. T. , Henein S. 
Published: January 2016

The size-dependent static deflection, pull-in instability and resonant frequency of a circular microplate under capillary force have been studied using modified couple stress elasticity theory. Size-dependency is a phenomenon in which the normalized quantities that classical elasticity theory predicts to be independent of the structure size, such as normalized deflection or normalized frequency, vary significantly as the structure size changes. This phenomenon has been observed in micro-scale structures such as micro-electro-mechanical-systems (MEMS). Since classical elasticity theory is unable to predict the size-dependency, non-classical elasticity theories such as modified couple stress theory have been developed recently.
In this paper, modified couple stress theory is used for the first time to develop the governing equation and boundary conditions of circular microplates when subjected to capillary force. Consideration of capillary force is important since it is has a significant role in the mechanical behavior and stability of micro-scale structures in the presence of a liquid bridge. We investigated the static deflection and pull-in instability of microplates using the Galerkin method to assess the effect of size-dependency for static deflection. We observed that, as the ratio of the microplate thickness to length scale parameter (an additional material property suggested in modified couple stress theory to capture the size-dependency) decreases, the normalized deflection of the microplate also decreases. We further observed that the difference between the normalized deflection predicted by classical elasticity theory and the one evaluated using modified couple stress theory is significant when thickness of the microplate is small, but diminishes as thickness increases. Furthermore, we defined a dimensionless number called the dimensionless capillary tension (DCT) as a function of the mechanical, geometrical and size-dependent properties of the microplate as well as the characteristics of the liquid bridge such as the contact angle and the interfacial tension. We showed that for DCT values greater than a threshold evaluated in this paper, pull-in instability happens and the microplate collapses to the substrate. Moreover, we evaluated the size-dependent resonant frequency of the microplate under capillary force as a function of the DCT and obtained the result that the frequency decreases as DCT increases. In addition, our investigation of size-dependency revealed that as the ratio of the microplate thickness to length scale parameter increases, the frequency decreases in a way that for large values of the ratio, it asymptotically approaches the value predicted by classical elasticity theory.
FEA Tire Modeling and Validation Techniques
Authors: Marjani Mehrsa , El-Gindy Moustafa , Philipps David , Öijer Fredrik , Johansson Inge 
Published: January 2016

Recent advances in power and efficiency of computerized modeling methods has made it easier to develop accurate tire models. These newer models are now created with such accuracy that it has become easy to predict the experimental tire’s behavior and characteristics. These models are helpful with determining tire, tire-road, and tire-soil interaction properties. By creating virtual models, the overall capital for research and development can be reduced as well as replacing unavailable experimental tires for research.
This research paper mainly focuses on the validation of computer generated FEA tire models which are then used for the prediction of the experimental tire’s rolling resistance, static and dynamic characteristics. Experimental data, such as rolling resistance and vertical acceleration are used in validation simulations in order to tune the virtual model to match the experimental tire’s behavior. The tire that was used for this research is a six-groove 445/50R22.5 FEA truck tire, which was constructed and validated over the course of this research.
Motorcycle Tire Modeling
Authors: Ballo Federico , Gobbi Massimiliano , Mastinu Giampiero , Previati Giorgio , Zerboni Roberto 
Published: January 2016

The knowledge of the actual distribution of the contact forces transmitted by the tire to the rim is of crucial importance for the lightweight design of motorcycles wheels.
In this paper, an analytical model of a motorcycle tire is developed and explicit formulae giving the distribution of the static radial and axial forces acting between the tyre and the rim for a given vertical load have been derived. The analytical model has been validated by means of a FE model of the tire and wheel and on the basis of indoor experimental tests.
The proposed analytical model is able to predict the radial static deflection of both a front and a rear tire for a racing motorbike with very good accuracy over a wide range of inflating pressures and vertical loads. The force distributions are in very good agreement with the results of the FE model.
Stability of Controlled Road Vehicles: A Preliminary Fundamental Study
Authors: della Rossa Fabio , Gobbi Massimiliano , Mastinu Giampiero , Piccardi Carlo , Previati Giorgio 
Published: January 2016

A comparison of the lateral stability behaviour between an autonomous vehicle, a vehicle with driver and a vehicle without driver (fixed steering wheel) is made by introducing a simple mathematical model of a vehicle running on even road. The mechanical model of the vehicle has two degrees of freedom and the related equations of motion contain the nonlinear tyre characteristics. The driver is described by a well-known model proposed in the literature. The autonomous vehicle has a virtual driver (robot) that behaves substantially like a human, but with its proper reaction time and gain. The road vehicle model has been validated.
The study of vehicle stability has to be based on bifurcation analysis and a preliminary investigation is proposed here. The accurate computation of steady-state equilibria is crucial to study the stability of the three kinds of vehicles here compared. The stability of the bare vehicle without driver (fixed steering wheel) is studied in a rather complete way referring to a number of combinations of tyre characteristics. The (known) conclusion is that the understeering vehicle is stable at each lateral acceleration level and at each vehicle speed. The additional (partially unknown) conclusion is that the vehicle (model) with degradated tyres may exhibit a huge number of different bifurcations. The driver has many effects on the stability of the vehicle. One positive effect is to eliminate the many possible different equilibria of the bare vehicle and keep active one single equilibrium only. Another positive effect is to broaden the basin of attraction of stable equilibria (at least at relatively low speed). A negative effect is that, even for straight running, the driver seem introducing a subcritical Hopf bifurcation which limits the maximum forward speed of some understeering vehicles (that could run faster with fixed steering wheel). Both the mentioned positive and negative effects appear to be applicable to autonomous vehicles as well. Further studies could be useful to overcome the limitations on the stability of current autonomous vehicles that have been identified in the present research.
Assessment of Design and Build Projects in Sophomore Design
Authors: Bannerot Richard 
Published: January 2016

One requirement in our sophomore design class is for the students to work in teams to design and build devices that satisfy several requirements subject to physical constraints. The evaluation of these devices is based on how individuals and the team perform on written documents as well as how well the device performs during testing and satisfies given design criteria. The performances in various parts of this assignment are used as a basis for student outcomes assessment. The paper will provide an example of a team project description including the figure of merit that assesses the functionality of the device and the rubric used to assess the quality of the design in four areas:
• creativity demonstrated in the design concept,
• creativity demonstrated in the execution of the concept,
• overall craftsmanship and esthetics, and,
• robustness,
plus a sales brochure.
Examples of student work and assessment documentation will also be provided.
Axial Crushing of Thin-Walled Tubes With Kite-Shape Pattern
Authors: Hou Degao , Chen Yan , Ma Jiayao , You Zhong 
Published: January 2016

Thin-walled tubes are widely used as energy absorption devices in automobiles, designed to protect the costly structures and people inside during an impact event through plastic deformation. They show excellent performance under axial loading in terms of weight efficiency, stroke distance and total energy absorption, but also have the disadvantage that the crushing force is not uniform during deformation process, especially with the existence of a high initial peak force. Recently, pattern design on tubular structures has received increasing attention. It has been found that, if the surface of a tube is pre-folded according to an origami pattern, the collapse mode of the tube can be altered, leading to changes in energy absorption performance. In this paper, we present a series of origami patterned tubes with a kite-shape pattern that is constructed by joining two pieces of Miura-ori. First of all, the geometry of the pattern is presented. We develop a theoretical model to predict the energy absorption associated with the axial crushing of the patterned tubes and derive a mathematical formula to calculate the mean crushing force accordingly. Secondly, a family of origami tubes with various profiles are designed, and their performances subjected to quasi-static axial crushing are numerically investigated.
A parametric study is also conducted to establish the relationship between the pre-folded angle of the pattern and the initial peak force as well as the mean crushing force. Numerical results show that introducing patterns to thin-walled tubes offers three advantages in comparison with conventional tubes, i.e., a lower initial peak force, a more uniform crushing load, and a stable and repeatable collapse mode. A 36.0% increase in specific energy absorption and 67.2% reduction in initial peak force is achieved in the optimum case. The new origami patterned tubes show great promise as energy absorption devices.
Teaching Interdisciplinary Design Between Architecture and Engineering: Finding Common Ground While Retaining Disciplinary Expertise
Authors: Li Timothy , Raghunath Nilanjan , Hölttä-Otto Katja , Arpak Asli , Nanayakkara Suranga , Telenko Cassandra 
Published: January 2016

Many educators agree that developing an interdisciplinary design curriculum is critical in creating the next generation of design professionals. However, literature surrounding the pedagogical challenges to undergraduate interdisciplinary design courses is limited. In this paper we study the initial challenges in developing and delivering an interdisciplinary design course. We observe from the perspective of the educators and the students in a newly synthesized co-taught design course that combines both architecture and engineering disciplines.
Through exploratory observations and analysis of student and instructor feedback throughout the semester, our findings suggest that disciplinary boundaries often influence pedagogical styles despite a concerted effort to create an interdisciplinary course that focuses on design. Despite agreement to interdisciplinary design teaching through shared lectures and activities, individual teaching methods varied, impacted by pedagogical norms from their respective disciplines. In response, students had mixed reactions to the varying presentation methods and critique feedback. This study, while preliminary in assessment, raises many questions about the challenges of teaching interdisciplinary design courses.
Nonlinear Effects of Bone Damping on Human Postural Balance
Authors: Shukla Amit , Bhattacharya Amit 
Published: January 2016

Osteoporosis is a common disease in women over the age of 50. The detection of this disease is done by an expensive bone mineral density test using dual energy x-ray absorpiometry. Osteoporosis patients are at a high risk of bone fracture under daily living conditions. Previous studies have shown that natural shock absorption capability of human body suffering from osteoporosis is significantly impaired.
This study is to develop an understanding of nonlinear effects of osteoporosis on human postural balance via computational models developed to capture changes in the shock absorption capabilities of human musculoskeletal system in osteoporosis patients. This paper uses a previously published, time delayed model of human postural balance by simulating the effect of osteoporosis via changes in damping factor. Numerical studies are presented and results interpreted to capture and highlight the nonlinear effects of osteoporosis on the dynamics postural balance response. This approach, upon further clinical evaluation can result in utilization of human postural balance test and the corresponding non-invasive Bone Shock Absorption test and measurement techniques for detection of osteoporosis.
Topology Optimization With Load Uncertainty as an Inhomogeneous Eigenvalue Problem
Authors: Song Wei , Lee Euihark , Gea Hae Chang , Xu Limei 
Published: January 2016

In this paper, a non-probabilistic based topology optimization method under an external load uncertainty is presented. In traditional topology optimization problems, external loadings that apply to structures are always assumed as deterministic, but an external loading with uncertainties is very common in many practical engineering applications. In this paper, load uncertainty is described as an unknown-but-bounded model and the maximum possible strain energy based topology optimization formulation under an uncertain load is solved for the worst case condition. This optimization problem can be rewritten as a two-level optimization problem: the upper level optimization problem is a deterministic topology optimization under a critical loading of the worst structure response, and the lower level optimization problem is to determine the critical loading corresponding to the worst structure response.
The challenge of the lower level optimization problem is on its non-convexity which makes many gradient based search methods ineffective. To overcome this issue, the lower level optimization problem is reformulated based on the KKT optimality conditions as an inhomogeneous eigenvalue problem and is solved for the critical loading corresponding to the worst structure response. After the worst loading case is identified, the upper level problem can be solved through the existing gradient based optimization algorithms. The effectiveness of the proposed topology optimization under unknown-but-bounded external loading uncertainty is demonstrated through a few numerical examples.
Magneto-Rheological (MR) Valve for Use in Hydro-Pneumatic Suspensions
Authors: Grobler Jacob F. , Els Schalk 
Published: January 2016

The suspension design requirements for vehicles that need both good on-road and off-road capabilities as well as vehicles where the payload changes significantly during operation is quite challenging. To overcome the ride comfort vs. handling compromise that most vehicles suffer from some suspension systems offer adjustability and control to overcome this conflict. The uptake of controllable dampers on commercial vehicles, allthough cost effective and technically feasible, have been low mainly because dampers on their own cannot significantly reduce the compromises involved with fully laden vs. empty or on-road vs. off-road use. The University of Pretoria developed a Four State Semi-Active Suspension System (4S4) that allows for the control and adjustability of the stiffness and the damping of the suspension. The 4S4 makes use of solenoid valves of which the response time unfortunately increases with an increase in flow, especially when implemented on larger vehicles, reducing the effectiveness of the control.
This paper presents an alternative to the solenoid valves currently used in the 4S4 in the form of a magneto-Rheological (MR) valve that acts as a normal continuously variable MR damper, but also has the ability to virtually block the flow of fluid, thus switching between the two different spring characteristics. Experimental results show that it is indeed possible to replace the solenoid valves with a MR valve.
Three-Dimensional Tooth Segmentation by Integrating Multiple Ray-Sum Images From CBCT Data
Authors: Barone Sandro , Paoli Alessandro , Razionale Armando V. 
Published: January 2016

The reconstruction of tooth anatomies is of utmost importance when dental implant surgeries and/or orthodontic corrections must be planned. In the last few years, cone beam CT (CBCT) has gained popularity in dentistry for 3D imaging of jawbones and teeth. However, within CBCT data sets, each tooth is defined by a region, which cannot be easily separated from surrounding tissues (i.e., bone tissue) by only considering pixel’s grey-intensity values. For this reason, some enhancement is usually necessary in order to properly segment tooth geometries.
In this paper, a semi-automatic approach to reconstruct individual 3D tooth anatomies by processing CBCT-scan data is presented. The methodology is based on the creation of a minimal number of 2D “local ray-sum” images by adding the absorption values of adjacent voxels along the most significant views for each tooth. The knowledge of the specific anatomical patient morphology drives the selection of these significant projection directions. The reconstructed “ray-sum” images greatly enhance the clearness of the root contours, which can then be interactively traced by dentists. A set of meaningful 2D tooth contours is consequently obtained and used to automatically extract a cubic spline curve for each transverse slice, thus approximating the overall 3D tooth profile.
The effectiveness of the methodology has been evaluated by comparing the results obtained for the reconstruction of anterior teeth with those obtained by using classical segmentation tools provided within commercial software.
Investigation of GPU Use in Conjunction With DCA-Based Articulated Multibody Systems Simulation
Authors: Laflin Jeremy J. , Anderson Kurt S. , Hans Michael 
Published: January 2016

Since computational performance is critically important for simulations to be used as an effective tool to study and design dynamic systems, the computing performance gains offered by Graphics Processing Units (GPUs) cannot be ignored. Since the GPU is designed to execute a very large number of simultaneous tasks (nominally Single Instruction Multi-Data (SIMD)), recursive algorithms in general, such as the DCA, are not well suited to be executed on GPU-type architecture. This is because each level of recursion is dependent on the previous level. However, there are some ways that the GPU can be leveraged to increase computational performance when using the DCA to form and solve the equations of motion for articulated multibody systems with a very large number of degrees-of-freedom.
Computational performance of dynamic simulations is highly dependent on the nature of the underlying formulation and the number of generalized coordinates used to characterize the system. Therefore, algorithms that scale in a more desirable (lower order) fashion with the number of degrees-of-freedom are generally preferred when dealing with large (N > 10) systems. However, the utility of using simulations as a scientific tool is directly related to actual compute time. The DCA, and other top performing methods, have demonstrated the desirable property of the required compute time scaling linearly with (O(n)) with the number of degrees-of-freedom (n) and sublinearly (O(logn) performance when implemented in parallel. However for the DCA, total compute time could be further reduced by exploiting the large number of independent operations involved in the first few levels of recursion.
A simple chain-type pendulum example is used to explore the feasibility of using the GPU to execute the assembly and disassembly operations for the levels of recursion that contain enough bodies for this process to be computationally advantageous. A multi-core CPU is used to perform the operations in parallel using Open MP for the remaining levels. The number of levels of recursion that utilizes the GPU is varied from zero to all levels. The data corresponding to zero utilization of the GPU provides the reference compute-time in which the assembly and disassembly operations necessary at each level are performed in parallel using Open MP. The computational time required to simulate the system for one time-step where the GPU is utilized for various levels of recursion is compared to the reference compute time also varying the number of bodies in the system.
A decrease in the compute-time when using the GPU is demonstrated relative to the reference compute-time even for systems of moderate size n < 1000 for arrangements using the GPU. This is a lower number of bodies than was expected for this test case and confirms that the GPU can bring significant increases in computational efficiency for large systems, while preserving the attractive sub-linear scalability (w.r.t. compute time) of the DCA.
A Novel Methodology for the Creation of Customized Eruption Guidance Appliances
Authors: Tilli Jacopo , Paoli Alessandro , Razionale Armando V. , Barone Sandro 
Published: January 2016

Within the orthodontic field, malocclusion problems are usually treated by using different types of appliances. In particular, Eruption Guidance Appliances (EGAs) are recommended for early orthodontic treatment or prevention of malocclusion problems. The traditional approach with EGAs is based on the use of standard prefabricated appliances. Experts in the orthodontic field believe that the customization of the EGAs would strongly enhance the results of malocclusion treatments.
This paper presents an innovative methodology for the design and manufacturing of fully customized EGAs. The methodology is based on an extensive integration between traditional orthodontic procedures with advanced computer aided design processes. The methodology moves from the digitalization of the plaster models obtained by optical scanning techniques. The patient morphology is then exploited, under dental practitioner supervision, for the design of the appliance geometry through CAD modeling tools. Medical guided assessment is required throughout the most of the data elaboration processes, in order to design the EGAs accordingly to the patient’s clinical conditions. Low-pressure injection molds for the physical manufacturing of the appliances are then 3D printed by using rapid prototyping techniques. The proposed methodology allows the production of patient customized appliances guaranteeing low cost manufacturing and high quality standards, similar to those typically obtained by in series productions. Moreover, the presented approach offers a high integration level with numerical and finite element methods, which can be used for evaluating the stress applied on the EGA, thus allowing the reinforcement of the appliance prior its manufacturing.