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This paper presents a review of recent advances in modeling and simulation of conventional metal machining processes, which continue to dominate a significant part of all machining processes, and in recent years, the need for predictive models for machining processes has grown in importance in the digital manufacturing age. Significant advances have been made in modeling the mechanics of cutting in conventional machining, driven by industrial need and enabled by rapid advances in computational power. The paper surveys the state-of-the-art in analytical and numerical modeling of conventional metal machining processes with a focus on their ability to predict useful performance attributes including chip geometry, forces, temperatures, tool wear, residual stress, and microstructure. Also included in the review is a discussion of the industrial use of modeling and simulation tools for conventional machining. Additionally, the practical applicability, implementation benefits, and methodological limitations of conventional machining process modeling have been examined. The paper concludes with a summary of future research directions in modeling and simulation of conventional metal machining processes. [ABSTRACT FROM AUTHOR]

The pulp and paper industry handles large amounts of energy and today produces the steam needed for the process and some of the required electricity. Several studies have shown that black liquor gasification and combined cycles increase the power production significantly compared to the traditional processes used today. It is of interest to investigate the performance when advanced gas turbines are integrated with next-generation pulp and paper mills. The present study focused on comparing the combined cycle with the integration of advanced gas turbines such as steam injected gas turbine (STIG) and evaporative gas turbine (EvGT) in pulp and paper mills. Two categories of simulations have been performed: (1) comparison of gasification of both black liquor and biomass connected to either a combined cycle or steam injected gas turbine with a heat recovery steam generator; (2) externally fired gas turbine in combination with the traditional recovery boiler. The energy demand of the pulp and paper mills is satisfied in all cases and the possibility to deliver a power surplus for external use is verified. The study investigates new system combinations of applications for advanced gas turbines. [DOI: 10.1115/1.1359773]

Kraft pulp and paper mills generate large quantities of black liquor and byproduct biomass suitable for gasification. These fuels are used today for onsite cogeneration of heat and power in boiler/steam turbine systems. Gasification technologies under development would enable these fuels to be used in gas turbines. This paper reports results of detailed full-load performance modeling of pulp-mill cogeneration systems based on gasifier/gas turbine technologies and, for comparison, on conventional steam-turbine cogeneration technologies. Pressurized, oxygen-blown black liquor gasification, the most advanced of proposed commercial black liquor gasifier designs, is considered, together with three alternative biomass gasifier designs under commercial development (high-pressure air-blown, low-pressure air-blown, and low-pressure indirectly-heated). Heavy-duty industrial gas turbines of the 70-M[W.sub.e] and 25-M[W.sub.e] class are included in the analysis. Results indicate that gasification-based cogeneration with biomass-derived fuels would transform a typical pulp mill into a significant power exporter and would also offer possibilities for net reductions in emissions of carbon dioxide relative to present practice.

Brittleness in paper is one of the primary reasons library books are removed from circulation, digitized, or have their access limited. Yet, paper brittleness is difficult to characterize as it has multiple definitions and no single measurable physical or chemical property associated with it. This study reevaluates the cantilever test as applied to aged papers. In this nondestructive test, the deflection of a strip of paper held horizontally is measured across its length. The deflection data are then fit to nonlinear bending theories assuming large deflection of a cantilever beam under a combined uniform and concentrated load. Fitting the shape of the deflection profiles provides bending and elastic moduli, the bending length, and confirms that the paper sheets respond linearly. The results are compared to those calculated from a simplified single point measurement of the maximum deflection of the cantilevered sample. Young's modulus measured by the cantilever test is lower for paper-based materials than that measured by tensile testing, and the bending modulus was found to correlate with the destructive Massachusetts Institute of Technology (MIT) fold endurance test. [ABSTRACT FROM AUTHOR]

A theoretical model for simulation of conventional steam-heated cylinder dryers is developed by considering the heat and mass transfer in a porous sheet during drying. Expressions for sheet shrinkage as a function of mass of water removed and for reductions in sheet porosity are derived for inclusion in the model. The interface thermal contact conductance of moist paper handsheet/metal interfaces has been experimentally investigated. A resulting empirical correlation, representing the thermal contact conductance between the cast iron dryer surface and paper web, is incorporated into the drying simulation model to reflect reductions in heat input to the sheet during drying. Finite difference techniques are used to obtain the numerical solutions. Average sheet moisture content and temperature along the length of the dryer section as well as average evaporation rates per cylinder are predicted by the model. Consideration of the internal dynamics of the drying process allows profiles of sheet moisture content, temperature, liquid flux, and vapor flux through the sheet thickness to be developed throughout the dryer section. Drying results are consistent with actual production cases. The model can be used to design dryer sections, study changes in operating conditions or in layout of a multi-cylinder dryer, or simulate the application of enhanced drying devices to a conventional drying section. The effect of the drum/paper contact conductance on drying rates and resultant dryer section requirements is provided as an example application of the model.

The extended meniscus and the intermolecular and capillary forces that govern its behavior and connection to change-of-phase heat transfer have been the subject of an increasing body of research over the past 50 years. We have been fortunate to be at the forefront of this effort starting from the development of a capillary feeder, in Earth's gravity, to stabilize film boiling to running a series of transparent heat pipe experiments aboard the International space station hoping to better understand the role of intermolecular forces in microgravity. The use of ellipsometry and interferometry to highlight the location and state of the vapor-liquid interface have been key to these studies and have helped to uncover many new, interesting, and sometimes unexpected phenomena associated with fluid flow and change-of-phase heat transfer. [ABSTRACT FROM AUTHOR]

Experiments were performed to investigate the thermal contact conductance of a paper handsheet/metal interface and the effective thermal conductivity of bone-dry paper handsheets. A linear regression model was derived for the thermal conductance as a function of pressure and basis weight. Results show that the overall joint conductance increases with increasing pressure and decreasing basis weight. A model was also derived for the effective thermal conductivity of the handsheets. Results show that thermal conductivity increases with increasing hand sheet density.

Presents information on a study which analyzed the heating and drying process of moist paper with infrared radiation energy. Set-up of the experiment; Description of paper samples; Error and theoretical analyses; Results of the study; Comparison of numerical and experimental results.

Fouling afflicts gas turbine operation from first time application. Filtration systems and washing operations work against air contaminants in order to limit the particles entering the compressor inlet and remove the existing deposits. In this work, a global overview of the operational experience of the manufacturer, the filtration systems, and the particle deposition of the compressor are reported. The data reported in this review have been collected from 60 years (1956-2015) of ASME Turbo Expo proceedings. This conference is recognized as the must-attend event for turbomachinery professionals. Through the years, many issues have been resolved by the contributions of this conference. Regarding the compressor fouling phenomenon, the contributions presented at the ASME Turbo Expo mark the high level of development in this field of research, thanks to the simultaneous presence of manufacturers, government, and academia attendees. The goal of the authors is to describe the technological evolution and challenges faced by manufacturers and researchers through the years, highlighting the state of the art in the knowledge of fouling, and defining the background on which further studies will be based. [ABSTRACT FROM AUTHOR]

Increasing atmospheric carbon dioxide from fossil fuel combustion is raising new interest in using renewable biomassfor energy. Modest-scale cogeneration systems using air-blown gasifiers coupled to aeroderivative gas turbines are expected to have high efficiencies and low unit capital costs, making them well-suited for use with biomass. Biomass-gasifier/gas turbine (BIG/GT) technology is not commercial, but efforts aimed at near-term commercialization are ongoing worldwide. Estimated performance and cost and prospects for commercial development of two BIG/GT systems are described, one using solid biomass fuel (e.g., wood chips), the other using kraft black liquor. At an energy-efficient kraft pulp mill, a BIG/GT cogeneration system could produce over three times as much electricity as is typically produced today. The mill's on-site energy needs could be met and a large surplus of electricity would be available for export. Using in addition currently unutilized forest residues for fuel, electricity production would be nearly five times today's level. The total cost to produce the electricity in excess of on-site needs is estimated to be below 4 cents per kWh in most cases. At projected growth rates for kraft pulp production, the associated biomass residue fuels could support up to 100 GW of BIG/GT capacity at kraft pulp mills worldwide in 2020 (30 GW in the US). The excess electricity production worldwide in 2020 would be equivalent to 10 percent of today's electricity production from fossil fuels., Electricity from biomass energy could decrease the amount of carbon dioxide emissions in the atmosphere produced by fossil fuels. A big impediment is the economical reduction of biomass energy into electricity. In the future, biomass from a single energy source could be used in biomass-gasifier/gas turbines(BIG/GT). The cost and feasibility of using BIG/GT in kraft pulp mills are analyzed. Two BIG/GT schemes using solid fuels or black liquor are presented. Results show that BIG/GT is a good source of electric power because of its high efficiency and the low investment required.

It was an honor to receive the Max Jakob Memorial Award for 2018. This invited paper is based on the award lecture and is written in an informal style expanding on the lecture and focusing on work in which I have been involved over the past 60-years. Early experimental and theoretical work was published only in conference proceedings when this was regarded an alternative to a journal and not, as seems to be the case nowadays, prior to journal publication or for incomplete work. I welcome this opportunity to clarify and make some of this earlier work more readily accessible. My comments on more recent work of others are also included. [ABSTRACT FROM AUTHOR]

Carbon-fiber-reinforced paper-based friction material (CFRPF), as a new type of wet friction material for automatic transmission, was prepared by a paper-making process. The frictional response of CFRPF is highly complex under a set of dynamically variable operating conditions. To better understand the effect of operating factors (braking pressure, rotating speed, oil temperature, and oil flow rate) on friction stability of the material, tests were carried out using a single ingredient experiment and the Taguchi method. Experimental results show that the braking stability and the dynamic friction coefficient ([[mu].sub.d]) decrease as braking pressure, rotating speed, oil temperature, and oil flow rate increase. The influence of braking pressure on [[mu].sub.d] is largest among the four operating factors. [[mu].sub.d] declines gradually during the first 3000 repeated braking cycles and changes very little subsequently due to the surface topography change in friction material. Keywords: paper-based friction material, carbon fiber, friction torque curve, dynamic friction coefficient

Oil-free microturbomachinery (OFT) implements compliant foil bearings because of their minute drag and ability to operate in extreme (high or low) temperature. Prominent to date, bump-foil thrust bearings integrate an underspring thin metal structure that provides resilience and material damping, and while the rotor is airborne, it acts in series with the stiffness and damping of the gas film. The design and manufacturing of foil bearings remain costly as it demands extensive engineering and actual experience. Alternative foil bearing configurations, less costly and easier to manufacture, are highly desirable to enable widespread usage of OFT. This paper details the design and manufacturing of a novel Rayleigh-step metal mesh foil thrust bearing (MMFTB) as well as its testing on a dedicated rig. Metal mesh structures offer significant material structural damping and can be easily procured at a fraction of the cost of a typical bump-foil strip layer. The MMFTB consists of a solid carrier, a number of stacked annular copper mesh sheets (wire diameter = 0.25, 0.3, and 0.41 mm), and a steel top foil (0.127 mm thick) that makes six pads (ID = 50.8 mm, OD =2 ID), each 45 deg in extent. A 3 μm polymer coats each pad, and a photochemical process etches a step 20 μm in height. Static and dynamic load measurements (without rotor speed) demonstrate that the MMFTB has structural stiffness and material damping similar to that of a publicized bump-type foil thrust bearing. A maiden test of the MMFTB with rotor speed of Ω = 15 krpm (~80 m/s at bearing outer diameter (OD)) proved briefly the bearing operation when applying a tiny thrust load. Further tests with ambient air, a rotor speed of 40 krpm (~212 m/s at bearing OD), and a very light load/area <7 kPa failed several of the prototype bearings, all exhibiting significant wear on one or more pads. The source of the failure is the inherent unevenness of the metal mesh stacked substructures, thus causing the pads to bulge toward the rotor collar surface before a load applies. A deficient anchoring method exacerbates the unevenness. Incidentally, a high rotor speed induced large windage that lifted the top foils pushing them against the spinning collar. As the bearing moved toward the rotating collar to begin applying thrust, the local high spots rubbed against the collar before a hydrodynamic wedge could form to separate the surfaces. Without a robust sacrificial coating, metal-to-metal contact quickly disfigured the contacting top foil pads, erasing the etched step, and leading to failure. In concept, and on paper, the mesh sheets and the top foil lay flat against the bearing carrier, giving a false sense of uniformity in the design process. In actuality, a designer must consider the manufactured states of the individual components and how they assemble. A redesign of the bearing intends to overcome the existing flaws (highlighted herein) by incorporating a thicker top foil that is well anchored (to better withstand the effects of windage), a robust sacrificial coating, and a hydrodynamic wedge accomplished via a circumferential taper on each pad. [ABSTRACT FROM AUTHOR]

In order to improve the precision of machining and reduce the processing cost of paper honeycomb core, a new method is presented to fix the honeycomb cote work piece to the working platform using magnetic and frictional forces. In this method, iron powder is used as a medium instead of the traditional adhesive-based material to achieve the bonding between the work piece and the working platform. Iron powder is poured into honeycomb cells until it reaches the desired height using a numerically controlled iron powder feeder system. In addition, a magnetic working platform is manufactured and placed on top of the station of the milling machine. The magnetic field produced by the magnetic working platform is leaded to the iron powder while the magnetic field control system switches on. More precisely, the mutual magnetic attraction between the iron powders located in different cells of the honeycomb and between the iron powder and the platform is generated. While cutting force is applied to the work piece, two types of friction force occur. One is between the iron powder and the wall of the honeycomb cells, and other one is between the work piece and the working platform. Once the resultant friction force balances the machining load, the work piece will be then fixed to the platform. In this paper, a new bonding system based on the new method is introduced and demonstrated. [DOI: 10.1115/1.2039944]

Origami is the art of creating a three-dimensional (3D) shape by folding paper. It has drawn much attention from researchers, and the designs that origami has inspired are used in various engineering applications. Most of these designs are based on familiar origami patterns and their known deformations, but origami patterns were originally intended for materials of near-zero thickness, primarily paper. To use the designs in engineering applications, it is necessary to simulate origami in a way that enables designers to explore and understand the designs while taking the thickness of the material to be folded into account. Because origami is primarily a problem in geometric design, this paper develops a geometric simulation for thick origami. The actuation, constraints, and assignment of mountain and valley folds in origami are also incorporated into the geometric formulation. The experimental results show that the proposed method is efficient and accurate. The method can successfully simulate a flat-foldable degree-four vertex, two different action origami, the bistable property of a waterbomb base, and the elasticity of non-rigid origami panels. [ABSTRACT FROM AUTHOR]

Carbon-fiber-reinforced paper-based friction material (CFRPF), as a new type of wet friction material for automatic transmission, was prepared by a paper-making process. The frictional response of CFRPF is highly complex under a set of dynamically variable operating conditions. To better understand the effect of operating factors (braking pressure, rotating speed, oil temperature, and oil flow rate) on friction stability of the material, tests were carried out using a single ingredient experiment and the Taguchi method. Experimental results show that the braking stability and the dynamic friction coefficient (μd) decrease as braking pressure, rotating speed, oil temperature, and oil flow rate increase. The influence of braking pressure on μd is largest among the four operating factors. μd declines gradually during the first 3000 repeated braking cycles and changes very little subsequently due to the surface topography change in friction material. [ABSTRACT FROM AUTHOR]

This paper is focused on the real area of contact for paper-based wet friction materials during the engagement of wet clutches. The deformation of the wet friction material is identified as elastic during the engagement. A microcontact model is proposed considering both surface roughness and skewness. A Weibull density distribution is employed in the model rather than a Gaussian density distribution. This model is compared with the Greenwood-Williamson (GW) model for the cases of positive skewness, zero skewness and negative skewness. The real areas of contact of new, run-in and glazed wet friction materials were investigated using this microcontact model. Both surface roughness and skewness were found to have a great effect on the real area of contact.

To understand the response of Alloy 617 to long-time exposure conditions and to determine the supplementary data needs for structural components in Gen IV nuclear reactors, literature of aging and aging effects in the alloy was reviewed. Most of the reviewed data were produced in connection with the international research effort supporting high temperature gas-cooled reactor projects in the 1970s and 1980s. Topics considered included microstructural changes, hardness, tensile properties, toughness, creep-rupture, fatigue, and crack growth. It became clear that, for the long-time very high-temperature conditions of the Gen IV reactors, a significant effort would be needed to fully understand and characterize property changes. Several topics for further research were recommended. [DOI: 10.1115/1.2967885]

No abstract.

The Journal of Biomechanical Engineering has contributed to biomechanical engineering field since 1977. To honor papers published at least 30 years that have had a long-lasting impact on the field, the Editors now recognize "Legacy Papers." The journal is pleased to present the following paper as this year's Legacy Paper: "A New Simplified Bioheat Equation for the Effect of Blood Flow on Local Average Tissue Temperature" by S. Weinbaum and L. Jiji, ASME Journal of Biomechanical Engineering 107: 131-139, 1985.

The friction characteristic of paper-based friction materials is one of the most important factors that influence the shifting performance of oil immersed clutches in automobile automatic transmissions. Visco-elasticity and porosity of the material are considered to be important properties that may control the friction characteristics of the material In this study, the relationship between the friction characteristics and the visco-elasticity of a paper-based friction material is discussed. In order to vary the visco-elasticity while retaining the ingredients almost constant in a paper-based friction material, the formulation of the sample materials required changing the compression rate during the clutch plate bonding process and changing the volume percentage of resin. The properties of the sample materials such as porosity (pore diameter, pore diameter distribution, porosity percentage), and visco-elastic deformation in the compressive and the shearing directions, etc. were measured. In order to clarify the relationship between the friction and visco-elasticity of friction material, friction characteristics were measured. Friction characteristics of the sample materials were evaluated by a breaking-away test and continuous slip tests with a newly designed friction testing machine. From the experimental results, which showed that the lower the longitudinal modulus of the friction material, the higher the friction coefficient, it was found that friction characteristics of oil immersed paper-based friction materials are influenced by the visco-elasticity.

The paper describes the development and description of the aerodynamic models used to estimate the aerodynamic loads on wind turbine constructions. This includes a status of the capabilities of compulation fluid dynamics and the need for reliable airfoil data for the simpler engineering models. Also a discussion of the use of passive and active aerodynamic devices is included such as, e.g.. Vortex Generators and distributed active flaps. Finally the problem of wakes in wind farms is addressed and a section of the likely future development of aerodynamic models for wind turbines is included. [ABSTRACT FROM AUTHOR]

This paper presents a new theory on frictional vibrations of paper-based friction material considering the interaction between its deformation and the consequent lubricant flow inside it. A frictional vibration model is proposed, in which a poroelastic body saturated by a viscous liquid is introduced, and then a stability criterion is derived on the assumption that vibrations in two directions, tangential and normal, are coupled. Compared with the experiment, it is confirmed that the proposed criterion can predict the stability limit more accurately than the conventional one, which does not take the deformation of the friction material into account and depends only on the slope of friction coefficient versus sliding velocity. Based on the present criterion, influences of material properties on the stability to frictional vibrations are discussed.

An experimental and analytical study has been performed on the effect of Reynolds number and free-stream turbulence on boundary layer transition location on the suction surface of a controlled diffusion airfoil (CDA). The experiments were conducted in a rectilinear cascade facility at Reynolds numbers between 0.7 and 3.0 x [10.sup.6] and turbulence intensities from about 0.7 to 4 percent. An oil streak technique and liquid crystal coatings were used to visualize the boundary, layer state. For small turbulence levels and all Reynolds numbers tested, the accelerated front portion of the blade is laminar and transition occurs within a laminar separation bubble shortly after the maximum velocity near 35-40 percent of chord. For high turbulence levels (Tu > 3 percent) and high Reynolds numbers, the transition region moves upstream into the accelerated front portion of the CDA blade. For those conditions, the sensitivity to surface roughness increases considerably; at Tu = 4 percent, bypass transition is observed near 7-10 percent of chord. Experimental results are compared to theoretical predictions using the transition model, which is implemented in the MISES code of Youngren and Drela. Overall the results indicate that early bypass transition at high turbulence levels must alter the profile velocity distribution for compressor blades that are designed and optimized for high Reynolds numbers. [DOI: 10.1115/1.1413471]

Theoretical analysis was carried out on the engagement process of a paper based wet clutch. The annular multidisk clutch in a SAE#2 tester was chosen as an example. The average flow model on partial hydrodynamic lubrication proposed by Patir and Cheng was employed for the analysis of squeeze motion taking the permeability, the compressive strain, and the asperity contact of paper facing into account. Simultaneously, the equations of heat conduction were solved to calculate the viscosity reduction due to frictional heat generation. The theoretical torque curve agreed qualitatively with the experimental one in spite of the many assumptions made in this analysis.

The thermal contact conductance of a paper/rubber elastomer interface, one of the parameters affecting heat transfer in printing, copying and papermaking processes. was investigated. Two silicon polymers were used as the elastomer interfaces while an aluminum interface was evaluated for comparison. It was revealed that overall conductance magnitude is directly related to pressure for all three interfaces because of interface compression.

An understanding of the mechanics of paper separation is very important to the design of reliable photocopiers, and in this paper a model is developed to simulate friction feed paper separation. The importance of such system parameters as roller acceleration and compressive load is demonstrated. The variability of friction coefficients is shown to have a significant effect on feeding reliability. Experimental data are shown to be in good agreement with predicted results. Recommendations are made for the design of reliable friction feed paper separators.

To understand the response of Alloy 617 to long-time exposure conditions and to determine the supplementary data needs for structural components in Gen IV nuclear reactors, literature of aging and aging effects in the alloy was reviewed. Most of the reviewed data were produced in connection with the international research effort supporting high temperature gas-cooled reactor projects in the 1970s and 1980s. Topics considered included microstructural changes, hardness, tensile properties, toughness, creep-rupture, fatigue, and crack growth. It became clear that, for the long-time very high-temperature conditions of the Gen IV reactors, a significant effort would be needed to fully understand and characterize property changes. Several topics for further research were recommended. [ABSTRACT FROM AUTHOR]

A model is developed for the heat and mass transfer in a paper sheet during the drying process. The model considers four phases of felt covered cylinder drying. Temperature and moisture content profiles of the sheet were obtained for each phase of the drying process and simulation results show that 65 cylinders are needed for drying before the sheet moisture can reach 6%. The present model is better compared to other models because it accounts for the internal dynamics of the drying process as well as the variations in sheet caliper and porosity.

In many machines handling lightweight, flexible sheets, the sheet must transit an open space. Examples include magnetic tape drives, xerographic copiers, and sewing machines. The nonlinear theory of the elastica has often been used to model nonlinear, static deflections. Dynamic modeling is more difficult, and far less studied. Recently, however, L. Mansfield and J. G. Simmonds (1987) have considered the dynamic deflection of a sheet emerging from a horizontal channel at constant velocity and subjected to gravity loading. In this paper, we consider a generalization of that problem to include arbitrary exit angles and an accelerating 'feed' rate. Gravity loading is retained. The resulting nonlinear equations of motion are tractable and are solved numerically.

A new test technique for measuring the flexural modulus of paper tubes is given. The testing procedure can be done in a rigid frame apparatus under constant load or in a universal testing machine under increasing load. The data obtained are studied using an altered Euler-Bernoulli theory to consider nonbending deflection components that are derived by the three-point-bend test. Results show that the method obtains a better value of the flexural modulus than classical methods.

The article announces the winners of the 2016 Summer Biomechanics, Bioengineering, and Biotransport Conference Student Paper Competition including John P. Carruth, Sonia Kartha, and Jack A. Martin.

Fluid injection is a common practice in the oil and gas industry found in many applications such as waterflooding and disposal of produced fluids. Maintaining high injection rates is crucial to guarantee the economic success of these projects; however, there are geomechanical risks and difficulties involved in this process that may threat the viability of fluid injection projects. Near wellbore reduction of permeability due to pore plugging, formation failure, out of zone injection, sand production, and local compaction are challenging the effectiveness of the injection process. Due to these complications, modeling and simulation has been used as an effective tool to assess injectors' performance; however, different problems have yet to be addressed. In this paper, we review some of these challenges and the solutions that have been proposed as a primary step to understand mechanisms affecting well performance. [ABSTRACT FROM AUTHOR]

An analysis of enhanced paper drying simulation model involved the formulation of a correlation for the contact conductance as a function of handsheet moisture content. The reduction in sample thickness, induced by enhancements in the applied load, resulted in enhanced handsheet density. A heat pipe effect inside the sheet, producing comparatively high values of paper thermal conductivity, might result in certain cases from the movement of liquid and vapor through the sheet coupled with evaporation near the hotter interface and condensation near the cooler interface.

Over the past few decades, folding paper has extended beyond the origami deployable applications to reach the engineering field. Nevertheless, mechanical information about paper behavior is still lacking, especially during folding/unfolding. This article proposes an approach to characterize the paper fold behavior in order to extract the material data that will be needed for the simulation of folding and to go a step further the single kinematics of origami mechanisms. The model developed herein from simple experiments for the fold behavior relies on a macroscopic local hinge with a nonlinear torsional spring. Though validated with only straight folds, the model is still applicable in the case of curved folds thanks to the locality principle of the mechanical behavior. The influence of both the folding angle and the fold length is extracted automatically from a set of experimental values exhibiting a deterministic behavior and a variability due to the folding process. The goal is also to propose a methodology that may extend the simple case of the paper crease, or even the case of thin material sheets, and may be adapted to other identification problems. [ABSTRACT FROM AUTHOR]