Shear Angle Research Articles

Stress-strain state of composite multi-layer stay rope considering breakages in reinforcing elements and nonlinear distribution of mechanical properties

Purpose. Formulation of an algorithm for considering the influence of continuity breakages in fiber reinforcing elements on stay rope strength. Methods. Construction and analytical solution of a mathematical model of interaction for parallel fiber reinforcingelements connected through elastic material, in a case of continuity breakage of individual elements in reinforcement. Findings. A static strength calculation algorithm for a multi-layer stay rope with breakages in one cross-section of reinforcing elements is developed. It is established that a continuity breakage of an arbitrary element of a stay rope reinforcement leads to a significant change in internal loads of only the adjacent reinforcing elements and is practically independent of a nonlinear deformation character of cable components. Greater loads on reinforcing elements occur in a case of breakage of a corner reinforcing element, and the smallest loads – in a case of breakage of a central one.It is established that a number of rows of reinforcing elements in a stay rope and location of a damaged reinforcing element do not significantly affect displacement of cable end and do not affect distribution of loads among reinforcing elements in a damaged cross-section. Displacements depend on a ratio of shear modulus of elastic material and Young's modulus of reinforcing elements; the ratio is varied along cable length. It is established that a reinforcing element location with discontinuity does not significantly affect the character of relative growth of stay rope deformations in a case of nonlinear character of elastic shell deformation. Deformation nonlinearity of cable components does not affect redistribution of forces in stay rope with damaged reinforcing elements. Maximum relative displacements of reinforcing elements and the resulting maximum shear angles of material located between reinforcing elements are smaller than a value of the assumed nonlinearity coefficient. Characters of displacements of reinforcing elements are qualitatively similar. Scientific novelty. An analytical algorithm is developed for calculating a stress-strain state of a multilayer stay rope considering its design, nonlinearly of mechanical properties of its components distributed along the cable with damage to an arbitrary group of reinforcing elements in one cross-section. Practical significance. The developed algorithm allows considering a nonlinear deformation character of stay rope components on its stress state in a case of breakages in an arbitrary number of reinforcing elements arbitrarily located in a stay rope with a continuity breakage in one cross-section. The algorithm can be applied to determine a stress-stress state of a stay rope with breakage in a cross-section infinitely distant from rope ends. The algorithm allows considering the influence of breakages in reinforcing elements on rope strength, which increases rope reliability in a structure.

Pengujian Karakteristik Tanah pada Daerah Ngasem Kediri Sebagai Dasar Perencanaan Konstruksi

Ngasem District, Kediri Regency is an area that is close to educational centers, shopping centers, and tourism areas, so it is suitable to build housing in the area. However, there were several residents' houses that were damaged, such as cracked floors and walls. One of the contributing factors is the condition of the soil. This study aims to conduct a soil investigation to determine the characteristics of the soil in the area by using laboratory tests including sieving gradation tests, atterberg limits, compaction and soil shear strength and the results show that the soil in the area is classified as SW-SC soil, namely well graded sand with a little clay mixture so it has low plasticity. In addition, the maximum dry unit weight was 1.76 gr/cm3, the optimum moisture content was 15.38% from the compaction test and the cohesion value was 0.894 kPa and the shear angle was 29.685° from the shear strength test. The results of this study can be useful in providing an overview of soil characteristics as a reference in construction projects.Keywords: soil characteristics, SW-SC soil, atterberg boundaries, Ngasem District

A novel study on the influence of graphene-based nanofluid concentrations on the response characteristics and surface-integrity of Hastelloy C-276 during minimum quantity lubrication

In present investigation, the impact of nanoparticle concentration on the machining accomplishment of Hastelloy C-276 has been examined in turning operation. The outputs like temperature, surface roughness, chip reduction coefficient (CRC), tool wear, and friction coefficient along with angle of shear have been estimated. The graphene nanoparticles (GnP) have been blended into soybean oil in distinct weight/volume ratio of 0.5, 1 and 1.5%. The experimental observations revealed that higher concentration of nanoparticles has enhanced the heat carrying capacity of amalgamation by 12.28%, surface roughness (27.88%), Temperature (16.8%), tool wear (22.5%), CRC (17.5%), coefficient of friction (46.36%) and shear angle (15%). Scanning electron microscopy identified nose wear, abrasion, adhesion and loss of tool coating. Further, lower tool wear has been noticed at 1.5% concentration, while the complete failure of insert has been reported during 116 m/min, 0.246 mm/rev having 0.5% concentration. ANOVA results exhibited that surface roughness is highly influenced by speed rate (41.66%) trailed by feed rate (28.16%) and then after concentration (13.68%). Temperature is dominated by cutting speed (69.31%), concentration (14.53%) and feed rate (13.25%). Likewise, tool wear was majorly altered by cutting speed (67.2%) accompanied by feed rate (23.90%) and thirdly concentration of GnP (5.03%).

Chip morphology and tool wear investigation in high-speed machining of AZ61 magnesium alloys using vegetable-oil based cutting fluid

ABSTRACT Lightweight alloys play a vital role in the development of automotive, biomedical and aerospace industries as well as other industrial sectors. The current study investigates the machinability of AZ61 magnesium alloy within a vegetable-oil-based MQL environment through high-speed orthogonal cutting. A tool wear and chip morphology examination are conducted along a full factorial experimentation to allow for adequate machinability testing. The usage of Grey Relational Analysis was invoked to allow for a multi-variant optimisation of input parameters such as MQL flow rate, cutting speed, and feed based on output responses, such as chip compression ratio, chip segmentation ratio, tool-chip contact length, and shear angle as well as tool wear evolution. Through the analysis of the formulated signal-to-noise data, it was found that the optimal cutting parameters were an MQL flow rate of 80 ml/h, cutting speed of 250 m/min and feed of 0.3 mm/rev. The optimal cutting conditions resulted in a Grey Relational Grade improvement of 0.177 as compared to the referenced experimental trail. The analysis of variance further concluded that the feed was the highest contributing input parameter at 38.04% followed by the MQL flow rate and the cutting speed.

Numerical and experimental study on vortex optimization in the forebay of a Sandy River

Because the movement of water and sediment is complex, the flow pattern in a forebay can be disordered, which can significantly affect the pumping efficiency of a pump station. Using a pumping station in Ningxia, a multiphase water–sand flow model is built based on field measurements and practical engineering. The vortex flow pattern and the cause of sediment deposition are analyzed by numerical simulations and experiments. Furthermore, 36 rectification measures are proposed to improve the vortex flow pattern and sediment deposition in the forebay. The results show that various rectification measures can correct the flow pattern disorder in the horizontal section of the forebay at different angles. However, the correction effect is not obvious in the slope section. For the first time, a combination plan of adding plates to the back wall of the pumping station is proposed. This strategy not only improves the vortex area of the horizontal section of the forebay but also diverts the vortices of the slope section, reducing the vortex range and the sediment content. At the same time, the flow velocity uniformity of the inlet section of the combined optimal solution increases by 19.22%, and the shear angle decreases by 8.81°. The combination of numerical simulation and experimental analysis demonstrates the accuracy of the combined plan, corrects the flow pattern in the forebay, and reduces the sediment content.

Experimental study on brittle-to-ductile transition mechanism of lower Silurian organic-rich shale in south China

Brittle-ductile transition conditions and mechanisms are key scientific issues embedded in the reservoir deformation-related difficulties faced during shale gas exploration and exploitation. In this study, shale deformation experiments under different temperatures, confining pressure and differential stress were conducted using a NaCl solid confining pressure medium, taking the Lower Silurian marine shale from South China as an example. We aimed to clarify the characteristic textures and structures of brittle and ductile deformation in organic-rich shale and then, to reveal the conditions and mechanisms of the brittle-to-ductile transition under the deep in-situ environment of high-temperature, high-confining pressure and high-stiffness surrounding strata. Deformation characteristics of experimentally deformed shale showed significant differences between brittle and ductile deformed shale in terms of fracture development, failure combining form, deformation distribution homogeneity, shear angle and the structures and textures within intensely deformed zones. The micro-deformation structures of brittle deformed shale are characterized by the development of fractures and the simple mechanical crushing of shale blocks and mineral particles. The strong deformation zones of ductile deformed shale mainly show micro-deformation features, such as solid-state rheological deformation and accompanying fragmentation, rounding and directional arrangement of mineral particles. Comparison of control group experiments supported the conclusion that increasing confining pressure significantly improves the elastic modulus and compressive strength of shale and leads to a transition from large-area uniform deformation to narrow-band concentrated deformation. A confining pressure of 75–100 MPa is required for the brittle-to-ductile deformation transition of the target shale at 200 °C. An elevated temperature enhances shale deformation in the yield and creep stages. Finally, we revealed the progressive process and mechanism of brittle-to-ductile transition with the increase of confining pressure; that is, increasing confining pressure leads to a gradual transition of the shale micro-deformation mechanism, from brittle failures to ductile rheological deformation, by suppressing tension fracturing and enhancing friction.

Developing a 2D finite element cutting model based on individual phases in orthogonal cutting of two-phase duplex stainless steel

This paper presents a novel method to model the metal cutting of 2205 duplex stainless steel alloy. A 2D finite element model was developed to predict the plastic behaviour of two phases of duplex stainless steel, austenite, and ferrite during orthogonal cutting. A mesh based on physical microstructure was created using mapping software OOF2. The finite model was setup on ABAQUS software based on the Lagrangian method. The cutting model allows for tracking of stress and strain on individual phases during chip formation. Simulated and experimental data showed good agreement in comparison of shear angle and cutting strain. Model was created to gain understanding of long-established issues in machining duplex stainless alloys. Future model development required to gain further insight on associated triggering mechanisms.

Meningkatkan Stabilitas Lereng Berdasarkan Pengujian Karakteristik Tanah

Kediri Regency has diverse potential and wealth, including natural resources, culture, and tourism. One example is the Dolo waterfall located in Jugo Village. In January 2023 there was an avalanche caused by heavy rainfall in the mountainous area of Jugo Village, Mojo District, Kediri. The landslide disrupted road access to tourist attractions, infrastructure and also affected the economy. Several studies have revealed that soil type, shear strength, and soil consistency properties are important in influencing a slope’s stability level. However, the discussion of landslide prevention efforts regarding soil and slope characteristics is still limited. This study aims to determine soil type, consistency properties, shear angle, soil cohesion, and slope safety factors in Jugo Village, Mojo District, Kediri Regency. Research begins with a survey and sampling, then testing is carried out in the laboratory and calculated the slope safety factor (Fs). The results revealed that the characteristics of the soil in Jugo Village influenced the landslides that occurred. Both the type of soil, the consistency limit, and the shear strength of the soil indicate that the slope is unstable, this is also indicated by the calculation value of Fs <1. The results of this study can be used as a reference in planning and carrying out slope stability at that location so as to prevent landslides in the future. The effort that can be done is to change the slope to 35° so that the slope becomes stable.

Mechanism and force modeling for cross-edges in the flank-end milling process based on the constrained cutting theory

Flank milling is one of the most important processes in modern industries. Traditionally, flank edges are taken as the main part to remove materials. However, cross-edges additionally have a great rule on the machining process. This paper studies the mechanism of removing materials for cross-edges. First, the mathematical model for cross edges is built. Then, angles for an arbitrary point on a cross-edge embracing the rake, clearance, and inclination angles are deduced. The constrained cutting situation is found in the zone between cross-edges and corresponding their connecting flank-edges. Based on this, the chip-formation mechanism for cross-edges is discussed in deep. Using mechanical principles, cutting forces model due to chips forming is put forward utilizing parameters such as the shear strength, the friction angle, and the shear angle, etc. To combine the effect of environment, tool wear, machine tools error, and so on, an empirical model is obtained from the mechanical one. This paper adopts two methods to verify the validity of the proposed theory. The first one is using FEM software to simulate the milling process to observe the deformation zone in the cutting area using two groups of parameters, the results of the shearing zones for flank- and cross-edges shows that the constrained theory can be used in the cross-edge milling process. Some experiments conducted are the other way to prove the correctness of the cutting forces model. The results also tell us that the model in this paper is valid and of high accuracy.

Determination of fracture toughness and yield strength of Inconel 718 by milling operation

This paper presents an analytical scheme to determine the fracture toughness and the yield strength of Inconel 718 by the widely used milling operation. It is noted that there exists material fracture at the tool tip and the removed layer of material undergoes plastic deformation along the primary shear plane. The fracture toughness is considered at the tool tip and the yield strength is applied on the primary shear plane. Subsequently, the modified Williams’ model and the modified Williams-minimization model are both proposed on the basis of the geometries and mechanics in the oblique cutting process. The modelling framework indicates that milling can be developed as an alternative method to determine the fracture toughness and the yield strength from the serrated chip thicknesses combined with the corresponding cutting forces. This is because the experimental method by milling is a convenient scheme as it only requires the cutting forces per unit width of cut with respect to a series of uncut chip thicknesses. In addition, the normal shear angle is predicted by applying the principle of energy minimization. Finally, milling experiments are conducted to validate the two proposed methods. Results show that the two analytical methods return similar values of fracture toughness and yield strength, respectively. Besides, it is noted that high values of yield strength are achieved based on Tresca criterion, which would indicate work hardening in the primary shear zone during the serrated chip formation. The proposed methods exhibit advantages of convenience and generality to derive the fracture toughness and the yield strength, since it is still a challenge for the traditional standard mechanical tests for Inconel 718 due to its toughness and ductility.

The influence of yarn fiber volume fraction, shear angle, and yarn spacing on crack propagation resistance of plain‐woven fabric‐reinforced epoxy composites

AbstractThis study investigated the effect of fabric parameters on crack propagation in plain‐woven e‐glass reinforced epoxy composite plates. Through numerical analyses, the study contributes to understanding the effect of fabric structure on crack propagation and adopting a more precise approach in the design of composite materials. The yarn fiber volume fraction, shear angle, and yarn spacing parameters were selected as variables for the plain‐woven fabric, and material properties were determined for each parameter using the composite homogenization method. A finite element model was created using the Ansys software package, and stress intensity factors (SIFs) and tear stress values were obtained under mode I loading to investigate the effects of fabric structure on crack propagation. The results showed that as the yarn fiber volume fraction ratio increased, the SIF values decreased and the T‐stress values increased. When evaluated according to the shear angle of the yarn, the lowest SIF value was obtained for the 0‐degree shear angle. The same was observed for T‐stress values as well. Additionally, compared to the fabric structure aligned along the X‐axis, a significant decrease occurred in the SIF value due to the perpendicular fiber density increase to the crack propagation direction with symmetric orientation.

Low-speed orthogonal cutting of large Zr-based metallic glasses: A shear angle model considering internal friction and serrated chip formation

Metallic glasses have high hardness, low cutting force, and serrated chip formation, which pose significant challenges for cutting. The chip formation mechanism of metallic glasses under low-speed cutting has been studied, but the effects of compression and internal friction have been neglected. In this study, a shear angle model that considers internal friction was proposed and compared with classical shear angle models. Low-speed orthogonal cutting experiments on Zr-based metallic glasses were conducted and the cutting forces, chip morphology, shear angle, external and internal friction angle under different cutting parameters were measured and calculated. The results show that the internal friction angle ranges from 21.3° to 36.0° and the shear angle ranges from 29.9° to 38.0°. The improved model can better characterize the cutting properties of metallic glasses. This study presents a new method and model for low-speed cutting of metallic glasses and provides insights into their deformation and fracture behaviors.

Machinability analysis of Ti-6Al-4V under cryogenic condition

Aerospace alloys are termed as hard to cut materials owing to their low thermal conductivity, high temperature strength and elevated chemical reactivity. Cryogenic conditions can be effectively deployed to improve the machinability and productivity while addressing environmental and sustainability concerns connected with high tool wear and the use of conventional cutting fluids. Current work was undertaken to develop a novel tool wear map under cryogenic condition using cutting speed and feed rate as input variables. The developed map was demarcated into regions of low, moderate and high tool wear zones in addition to an unusually high wear zone, termed as avoidance zone existing between cutting speeds of 65–95 m/min and feed rates of 0.18–0.22 mm/rev. Characterization of developed map in terms of tool chip contact length revealed its direct relationship with cutting speed and feed rate accounting for the formation of different wear regions. Elemental analysis of avoidance zone detected high presence of TiN which results in larger tool chip contact length owing to its higher thermal conductivity. Chip morphology characterization highlighted an increase in chip compression ratio and decrease in shear angle due to the reduction of effective tool rake angle, further elevating the cutting zone temperature promoting wear. SEM and EDS spot analysis indicated the presence of adhesive and diffusion-dissolution wear mechanisms as the tool wear progresses. Comparative analysis with dry condition indicated that tool life is enhanced up to 100% using cryogenic media. Analysis of cryogenic tool wear map underscored the importance of careful choice of machining parameters in terms of increase in MRR up to 36% and tool life up to 58%. Overall, cryogenic tool wear map presents graphical interpretation of the machinability of Ti–6Al–4V in terms of tool wear.

ENERGY MODEL OF SOILS AND ROCKS CUTTING DURING WELL DRILLING

The article deals with the process of cutting soils and rocks. Experimental studies show that a coneshaped wedge is formed on the cutting surface. The compacted core of the deformed material contributes to the formation of tensile forces, under the action of which the material is destroyed along the sliding surfaces at a shear angle. An energy model for cutting soils and rocks while drilling wells, consisting of four parts, is proposed. The model is aimed at minimizing the energy consumption of the cutting process during well drilling. It is proposed to determine the chisel rotation speed by the length of the crack that occurs during brittle fracture of materials.

Investigation of a stress-strain state of a rubber-cable rope with cables of different tensile rigidity

Purpose. Establishment of dependences for stress-strain state parameters in a rubber-cable rope with cables of different tensile rigidity and cable breakage. Research methodology. Construction and development of an algorithm for solving a model of a stress-strain state of a rubber-cable rope with ropes of different tensile rigidity and breakage of one cable by using the methods of mechanics of layered composite materials with soft and hard layers. Findings. Analytical expressions are constructed, which allow determining the main stress-strain state indicators in a rope with an odd number of cables, while the middle cable is damaged, and tensile rigidity of the middle cable is half the tensile rigidity of the other cables. Analytical dependencies are established for determining the extreme angles of rubber shear between the cables, what allows determining the most dangerous tension states of a rope with a damaged cable, which has a different rigidity from the other cables. The level of reliability of the developed algorithm for solving the model of a stress-strain state of a rubber-cable rope with cables of different rigidity is confirmed by determining the maximum tensile forces of a rope made of three cables, in which the middle cable has a tensile rigidity half that of the other two. The force distribution coefficients between cables adjacent to the damaged one are equal to 1.25 per unit load on each cable, which corresponds to the only possible case of force distribution between parallel elements under the presented conditions. Scientific novelty. The character of influence of different rigidity and damage of the reinforcing cables on the main parameters of stress-strain state in a rubber-cable rope are established. Practical significance. An algorithm for determining the stress-strain state indicators of a rubber-cable rope, which has an odd number of reinforcing cables, its middle cable is damaged, and the tensile rigidity of the middle cable is different (lower) than the rigidity of the other cables, is developed. This makes it possible to increase the operational safety of rubber-cable ropes in hoisting and transporting machines, in particular when operating at significant lifting heights, and also contributes to justifying the use of a rope design as a stay rope in capital structures.

Acoustic emission parameters and energy dissipation law of cyclic load and unload damage of dihydrate gypsum under different loading rate

In order to explore the effect of loading rate on physical and mechanical properties of dihydrate gypsum, cyclic loading and unloading mechanical tests were carried out at different loading rates. Test results were analyzed from the aspects of stress-strain curve, energy distribution mode, damage law and failure mode of specimen. The main research results obtained in the thesis are as follows: with the increase of the loading rate, the peak value of specimen damage first increases rapidly, and then in-creases slowly, and there is a damage threshold. In the early stage of loading, the dissipated energy of the specimen accounts for about 70% of the total energy, most of the total energy input is converted into dissipated energy. The elastic energy density shows an increasing trend with the increase of the loading rate. The elastic energy density is the highest when the loading rate is 400 ​N/s, and more elastic energy can be stored. The ratio of elastic energy ue/u increases with the in-crease of loading rate and tends to be stable. The acoustic emission data show that the acoustic emission signals present a certain agglomeration phenomenon at the unloading point, and there is a “blank period” between the unloading point and the emergence of the next acoustic emission activity. In the early stage of specimen loading, friction-type acoustic emission is mainly generated. The cumulative ringing count when the load reaches the peak failure stress at low loading rate is more, indicating that low loading rate will produce more acoustic emission activities. With the increase of loading rate, the cumulative ringing number per unit time increases, indicating that the increase of loading rate accelerates the damage and failure of dihydrate gypsum near the peak value. The failure mode of gypsum specimens is shear failure, and the increase of loading rate of shear failure angle shows an increasing trend. The larger the loading rate is, the higher the strength of the specimen is. The more energy the press inputs during the loading process, the higher the energy absorbed by the unit volume specimen, which aggravates the development, expansion and penetration of the internal cracks of the specimen, resulting in the larger shear angle of the specimen. The test results provide a more comprehensive theoretical basis for the study of damage characteristics of dihydrate gypsum during cyclic loading and unloading.

An analytical cutting force model for elliptical vibration texturing of nano-grating surfaces

Although the direct texturing processes using dynamic cutting depth modulation have been widely demonstrated for generating micro/nano-structured surfaces, the material shearing removal dominates the surface topography generation that inevitably inhibits the machining feasibility of high-aspect textures. This paper proposes a novel nano-grating generation mechanism governed by the combined effect of shearing-based material removal and compressive forming-based deformation in elliptical vibration texturing. A newly dynamic cutting force model is established to reveal its transient cutting mechanics that incorporating the process elastic rebounding behaviors and essential local cutting characteristics in three deformation zones. The model fully considers the complex transient shear angle variation, friction reversal phenomenon on tool-chip interface as well as the unique flank-waviness interaction. A series of texturing experiments are delicately designed to modulate the contribution of material shearing removal and flank compressive forming on nano-grating generation mechanism. The measured dynamic cutting force show good agreements with the simulated results, based on which the model accuracy and main process assumptions are well validated. Furthermore, the relationship between the cutting force characteristics and nano-grating topography is analyzed to guide the optimal elliptical trajectory designs for simultaneously achieving high-quality nano-gratings and smaller dynamic cutting forces. The outcomes of this paper not only lay the scientific foundations for machining capability extension of direct texturing processes, but also contribute to the understandings of combined surface generation mechanisms of other intermittent cutting processes in nano-scale domain.

Effects of spring gripper configuration and forming temperature on the thermo-stamping of a carbon-fiber woven-fabric/polyphenylene sulfide composite sheet

Although thermo-stamping is one of the fastest and most cost-effective processes in the production of fabric-reinforced thermoplastic composite parts used in aerospace and automotive industries, it is quite prone to result in many defects. In particular, wrinkling is a frequently encountered defect in the production of doubly curved parts and is very sensitive to process parameters. Finite element analysis is an effective tool for estimating defects that can occur during the thermo-stamping process. In this study, effects of spring configurations in spring-based holders and forming temperature on wrinkling and shear deformation are investigated experimentally and numerically by using two different spring configurations and three different forming temperatures. Non-isothermal and isothermal approaches used in thermo-stamping simulations are compared in terms of wrinkling estimation and shear angle distribution. The results reveal that while the wrinkle predictions obtained by the non-isothermal approach are in good agreement with the experimental results, the isothermal approach cannot predict any of the wrinkles obtained in the experiment. Furthermore, the obtained results confirm that spring gripper configurations and forming temperature have a significant effect on wrinkling and shear angle distribution.

Single Breath-Hold MR Elastography for Fast Biomechanical Probing of Pancreatic Stiffness.

Pancreatic ductal adenocarcinoma (PDAC) stromal disposition is thought to influence chemotherapy efficacy and increase tissue stiffness, which could be quantified noninvasively via MR elastography (MRE). Current methods cause position-based errors in pancreas location over time, hampering accuracy. It would be beneficial to have a single breath-hold acquisition. To develop and test a single breath-hold three-dimensional MRE technique utilizing prospective undersampling and a compressed sensing reconstruction (CS-MRE). Prospective. A total of 30 healthy volunteers (HV) (31 ± 9 years; 33% male) and five patients with PDAC (69 ± 5 years; 80% male). 3-T, GRE Ristretto MRE. First, optimization of multi breath-hold MRE was done in 10 HV using four combinations of vibration frequency, number of measured wave-phase offsets, and TE and looking at MRE quality measures in the pancreas head. Second, viscoelastic parameters delineated in the pancreas head or tumor of CS-MRE were compared against (I) 2D and (II) 3D four breath-hold acquisitions in HV (N = 20) and PDAC patients. Intrasession repeatability was assessed for CS-MRE in a subgroup of healthy volunteers (N = 15). Tests include repeated measures analysis of variance (ANOVA), Bland-Altman analysis, and coefficients of variation (CoVs). A P-value <.05 was considered statistically significant. Optimization of the four breath-hold acquisitions resulted in 40 Hz vibration frequency, five wave-phases, and echo time (TE) = 6.9 msec as the preferred method (4BH-MRE). CS-MRE quantitative results did not differ from 4BH-MRE. Shear wave speed (SWS) and phase angle differed significantly between HV and PDAC patients using 4BH-MRE or CS-MRE. The limits of agreement for SWS were [-0.09, 0.10] m/second and the within-subject CoV was 4.8% for CS-MRE. CS-MRE might allow a single breath-hold MRE acquisition with comparable SWS and phase angle as 4BH-MRE, and it may still enable to differentiate between HV and PDAC. 2 Technical Efficacy Stage: 2.

Modeling energy consumption inside cutting deformation zone to predict the stress distributions, temperature and microstructure by micro irreversible entropic thermodynamics

It is important to analyze the process of chip formation by means of the energy consumption during metal cutting, which is related to the cutting power (or cutting force), the cutting temperature and the machined surface integrity. In this study, the consumed energy field inside the cutting deformation zone is established by considering four micro irreversible processes including the dislocation generation, annihilation, movement, and continuous dynamic recrystallization. A new shear-angle solution is proposed on the basis of the steady conditions of irreversible processes (i.e., the entropy production rate reaches the minimum), whose adequacy is verified by the experimental results of the shear angle and friction coefficient along the tool-chip interface. Based on the predicted consumed energy field inside the cutting deformation zone, the deformation mechanism, microstructure, stress and temperature are predicted and analyzed. The results show that three stages including the loading stage, unloading stage and steady stage are divided during chip formation according to the consumed energy field. The consumed energy and statistically stored dislocation density are both of gradient distribution in the primary shear zone, and continuous dynamic recrystallization is the main mechanism of grain refinement during chip formation, which is dominated in the secondary deformation zone. The stress and temperature inside the cutting deformation zone as well as the hardness of the machined surface are predicted according to the energy balance relationship and consumed energy field, indicating the feasibility of using energy consumption to comprehensively describe the internal changes of workpiece material inside the cutting deformation zone.