text stringlengths 0 1.19M |
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= 2 again occupy regions of higher Θ∼ values than those of Eθ/Er |
= 0.5 do, and the sizes of instability regions for Eθ/Er |
= 2 are smaller. In addition, (a)–(f) again reveal that the primary instability regions are all larger than the secondary instability regions, another tendency consistent with results displayed in The widths of the primary and secondary instability regions ΔΘ∼ versus rotational speeds Ω∼ are plotted in , where the inst... |
= 0.5 and 2. It is observed that increasing thickness of the viscoelastic core layer results in a wider instability region, i.e., a larger value of ΔΘ∼. In addition, a lower modulus ratio also results in a wider instability region. Besides, it is also observed that a higher rotational speed makes the instability region... |
= 0.5 and 2. It is observed that increasing E∼2 first reduces the instability region which reaches a minimum before it increases, i.e., the value of ΔΘ∼ decreases to a minimum before it increases. It is known that increasing E∼2 increases both stiffness and shear effects. When the value of E∼2 is small, the effects of ... |
< 373 K and T |
> 573 K. Due to the low temperature and the instability of the alloy, the CTE shows lower values at T |
< 373 K, and as a result of the increased solid solubility of Si in Al, the CTE values decrease at T |
> 573 K. Between 373 K and 573 K, the experimental CTEs lie between the Turner model and the lower bound of the Schapery model, which indicates that the experimental CTEs agree well with the theoretical models and that the elastic interactions are dominant in their CTEs during this temperature range. displays the calcu... |
× |
hc |
× width). The density of corrugated composites used in this study was 163 kg/m3.Longitudinal tensile specimens were 200 mm long with 40 mm rectangular aluminum end-tabs, leaving a 120 mm gauge section. Transverse tensile specimens were 150 mm long with 35 mm aluminum end-tabs. The aluminum tabs were bonded to the speci... |
= |
A22 and D11 |
= |
D22), and this behavior is implicit in the following formulations. Material anisotropy should be incorporated into the analytical model when treating the corrugated composites manufactured from other fabrics.The longitudinal Young’s modulus of the corrugated composites, ELeff, can be predicted from considering the volu... |
= 4.96 × 106 (N/m) and D11 |
= 0.0056 (N/m). Using these effective properties of plain woven fabrics, the tensile and flexural stiffnesses of the corrugated composites were calculated using Eqs. . Comparison between predicted and experimental results is shown in , in which slight differences are observed between the two. As the reproducibility of ... |
μ, where μ is the shear modulus and is independent of the orientation of the applied stress. It is shown that this high Peierls stress at 0 K is a consequence of the angular interactions in the MEAM potential. The kink-pair formation energy at zero applied stress is found to be low and equal to 0.16 eV. NVT molecular d... |
= 0.16 eV, obtained from 3-D molecular statics simulations. Now, the minimum velocity detected in the simulations is ∼1 m s−1. For this velocity, from Orowan’s expression, dε/dt |
= ρbv, where ρ is the mobile dislocation density and b is the Burgers vector of the dislocation, one obtains dε/dt in the simulations as ∼100 s−1 for a mobile dislocation density of 1012 |
m−2. The experimental strain rates are in the range 10−4–10−6 |
s−1. For the experimental strain rates, C for α-Ti becomes 0.134 K−1/2 (Eq. (6)). The model strain rate – experimental strain rate in corresponds to σ/σp |
= (1.0 − |
CT0.5)2 with C |
= 0.134 K−1/2, and represents kink-pair model data corrected for the much lower strain rate present in experiments. Also, ΔH/kT in experiments is calculated to be ∼34 which is very close to the experimentally determined value of ∼36 are the experimental critical resolved shear stress data for a/3〈112¯0〉 screw dislocat... |
< 0.01 μm) with a 6-μm diamond suspension and cleaned in a multi-stage ultrasonic cleaning bath with alkaline solutions of different concentrations and finally rinsed with de-ionized water and dried with nitrogen.The Al2O3 films were deposited in a laboratory-sputtering device (Z400, Leybold-Heraeus) equipped with a bi... |
= 395.6 nm) measured by OES and the cathode voltage as function of the percentage of oxygen flow during the reactive sputtering process are presented in . By increasing the oxygen flow, a constant decrease of the aluminum lines intensity and of the cathode voltage was observed.No γ-Al2O3 peaks were detected by XRD exam... |
= 0.780 nm) On the other hand, the adjusted low pressure (0.2 Pa) can help to increase the mean free path of sputtered particles, hence increasing their average kinetic energy , four zones corresponding to four different ranges are differentiated. According to XRD and SEM examinations, as well as nanoindentations, coat... |
= 0.780 nm), which allows the formation of arranged crystalline structures. Therefore, γ-Al2O3 peaks can be seen in the XRD examinations (see b and c). The fourth zone is a poisoned target zone, where the target is almost completely oxidized. From the target only few metallic atoms are still sputtered and supposable mo... |
= 2Al2O3 in process is reduced because fewer Al atoms are available to react.A big influence of the oxygen flow on the coating hardness is clearly observed in , which can be associated to the coating structures. Metallic films deposited in zone 1 exhibited a maximal hardness of 1.2 GPa. The hardness of the amorphous fi... |
= 0.780 nm), which allows the formation of arranged crystalline structures. The significant influence of the oxygen flow on the PVD-alumina hardness was verified in this investigation. Alumina hardness increased by increasing oxygen flow until crystalline alumina structures (γ-Al2O3) were synthesized. The γ-Al2O3 coati... |
s−1, respectively. Previously, the average lifetimes of DCVJ and DASPI were measured in PAA (MW 240,000) as 1.67 and 1.95 ns. When the kr values of 2.8 × 108 |
s−1 for DCVJ Electrospinning is an effective technique to synthesize various polymer fibers , nanofibers were successfully formed without beads or pores and had a size distribution range of 200–400 nm. The apparent structure of the PAA fibers is relatively more linear than that of PEO, implying that PAA has a higher me... |
s−1, 1 × 10−7 |
s−1 to 1 × 10−6 |
s−1 respectively, the results show that the tensile strength increases as the strain rate increases while the peak AE hit rate decreases. Meanwhile, the specimen under a relatively higher strain rate shows a relatively wider intrinsic process zone in a more diffuser manner, lots of distributed microcracks relatively de... |
s−1) on quasi-static flexural-tensile properties of hydraulic concrete was investigated using AET. Cumulative AE events, cumulative AE hits, AE hit rates obtained through TPB tests on hydraulic concrete specimens under low loading rates were used to identify the stage characteristic of the fracture process. More emphas... |
s−1) on two specimens with a notch respectively. For the former, the CSS4410 universal testing machine, manufactured by Changchun Research Institute for Mechanical Science (CRIMS), was used. This machine adopts EDC 100 digital control system (manufactured by DOLI, Germany), which provides two kinds of increment control... |
s−1, 10−7 |
s−1 and 10−6 |
s−1, respectively. TPB flexural tests on notched specimens were conducted using the triaxial compressive testing machine with a maximum capacity of 5000 kN by CRIMS. These tests took about 0.5–0.7 h due to low loading rates.The SAMOSTM AE system manufactured by the Physical Acoustic Corporation (PAC) was used for the A... |
s−1) vary more or less: (1) under relatively lower strain rates, microcracking localizes in a narrower band close to the midspan, and failure of a specimen in this condition can be attributed to propagation of one of a few main macrocracks created by microcracking localization close to the midspan; (2) but under relati... |
s−1, 1 × 10−7 |
s−1 to 1 × 10−6 |
s−1 respectively. Further tests, namely the combination measurement of AE and local deformation of TPB flexural tests on notched specimens, were also conducted to verify the correlation between AE events and microcracking localization. As a result of the study, the following conclusions can be drawn.In the very low str... |
cm−2; this implies a dislocation spacing of 1 to 10 μm. A typical indentation test in the elastic regime probes a maximum lateral region of two hundred nanometers up to the point at which the pop-in occurs. This suggests that the volume of material sampled by the indentation test at pop-in is smaller than the average d... |
= 244 GPa gives Er |
= 217 GPa. If we insert the 0.7 μm tip radius into Eq. , we obtain a maximum shear stress for each pop-in load. This maximum shear stress is responsible for the homogenous dislocation nucleation at zτ(max).The predominant slip system in FeAl is 〈111〉 {110} at room temperature where W is the line energy of the dislocati... |
= 0. This condition and dΔG/dr |
= 0 for a maximum are fulfilled, ifThe corresponding critical load Pc for a pop-in is obtained from Eq. according to this criterion and by using the constants given in . The reduction of the pop-in load by about a factor of 3.5 corresponds to a decrease of W by 40%. According to Eq. this reduction can be attributed to... |
W/(m2 |
K)), otherwise the numerical change of h could be small (e.g., change steps to be 1 × 103 |
W/(m2 |
K)). Repeat steps (3), (4), and (5) until the error to be lower than 1%. The flow chart is illustrated in Fcw=L∫0VB(1−τ0σ0)τ0dx+L∫VB(1−τ0σ0)VBμσ0VB−x2VBdx,ifVB<VB*Fcw=L∫0VB(1−τ0σ0)τ0dx+L∫VB(1−τ0σ0)VBμσ0VB−x2VB2dx,ifVB>VB*where σ0 and τ0 are the normal and shear stress at the tool nose, which can be calculated by the sl... |
1.92tc |
− 0.09tu (), although it is influenced by feed rate. The chip deformation coefficient, denoting the ratio of cut chip thickness (tc) to uncut chip thickness (tu) was given a mean value of 1.25 (). Temperature-dependent thermal conductivities are used in the simulations. The heat conduction coefficients of tool coating ... |
kg water/(kg dry matter s) was found for microwave-assisted drying, which results into a product of intermediate water activity. Combining VMD with osmotic dehydration or air drying did not improve drying efficiency. VMD yields an elastic product of improved mechanical resistance with just a slight loss of color and an... |
a), the degree of yellowness or blueness (± |
b) and the degree of lightness (L), using the Color Quest II Hunterlab colorimeter (Hunter Associates Laboratory, Inc., Reston, VA, USA). This instrument was calibrated at the beginning of each experiment with a white ceramic plate. Results were expressed in a⁎, b⁎ and L⁎ color coordinates of the Commission Internation... |
= (a⁎f |
− |
a⁎0), Δb |
= (b⁎f |
− |
b⁎0) and ΔL |
= (L⁎f |
− |
L⁎0). The subscripts 0 and f indicate fresh and dehydrated states, respectively. Each strawberry was scanned at three different locations using ten fruits per treatment.Texture characteristics of strawberries were measured by the Instron Universal Testing Machine (ID 4467 H 1998, Instron Co., Norwood, MA, USA). At leas... |
< 0.05) using Statgraphics Centurion XVI version 16.1.15 (Statpoint Technologies, Inc., Warrenton, VA, USA). Differences on the mean values were assessed by Duncan's multiple range test at a significance level of p |
< 0.05 to discriminate among the means using the Fisher's least significant difference procedure.The drying rate for dehydrated strawberry samples is shown in . It is evident that water removal from fruit is dependent on the drying method. The drying rate for hot air drying was found to be 6.0 × 10− 4 |
kg water/(kg dry matter s). This value agrees with the maximum drying rate for convective drying of strawberries at 65 °C as reported by , where the drying rate decreased with moisture content. The drying rate determined for microwave assisted drying was about 12% higher than the convective air drying rate (). Microwav... |
= 0.92). Soluble solids, amongst others organic acids, were concentrated after water removal reducing water activity down to between 0.70 and 0.80. This intermediate water activity yields into dry, firm and flexible products without growth of most of the bacteria, yeast and molds (). The water sorption isotherm of stra... |
= |
Depdε, with dσ denoting the incremental stress vector, dε the incremental strain vector and Dep the constitutive elasto-plastic matrix. The yield surface F(σ, |
α, |
κ) = 0 determine the stress level at which the plastic deformation begins. The material property matrix Dep is defined aswhere n |
= ∂F/∂σ and ng |
= ∂Q/∂σ are the normal vector to the yield and potential plastic surfaces, respectively, and H is the hardening plastic modulus defined as where dλ is the plastic multiplier and μ=(ep,εvp).In order to derive the constitutive elasto-plastic matrix and its components, we need to calculate De, n, ng and H in Eq. . The nor... |
= ±ϕhfh and one more from fd |
= 0.0, which has been defined in Eq. . If fd |
= 0.0 does not lead to any value for J1, the yield surface of Eq. yields to two roots for J1, i.e. J1 |
= ±ϕhfh, which results in an elliptical shape in meridian plane. The 3D representation of the yield surface in principal stress space for different values of isotropic hardening, where the intersection point of yield surface with J1-axis are −ϕhfh and +ϕhfh. This representation clearly shows how the yield surface grow... |
= 0.0 leads to the value of J1 between −ϕhfh and +ϕhfh, the cone-cap yield surface will be produced from Eq. based on the intersection points of J1 |
= −ϕhfh and the value obtained from fd |
= 0.0, as shown in for different values of isotropic hardening. As can be observed from this figure the yield surface grows with densification and reduces to the Drucker–Prager yield function for full dense bodies. This yield surface is very similar to the double-surface cap models, i.e. a combination of Mohr–Coulomb ... |
= 0.1) in the very high cycle fatigue (VHCF) regime. The ultrasonic fatigue testing method with a cycling frequency of about 20 kHz has been further developed for these experiments. Sheet specimens with 0.35 mm thickness are mounted on a carrier specimen, they are pre-stressed and are forced to vibrate jointly. Between... |
= 1.3 MPa m1/2 and 2.4 MPa m1/2. The sizes of crack initiating inclusions influence fatigue lifetimes. This is considered in a crack propagation model and by presenting lifetimes versus the stress amplitudes multiplied by (areaINC)1/12. A mean lifetime of 109 |
cycles is found at a stress amplitude of 22% of the tensile strength, which is comparable to other high strength steels tested under cyclic tension.Several components and parts used in the transportation industry, in power plants or in medical devices are stressed with very high numbers of load cycles during service. E... |
= 0.1. Ultrasonic testing is well suited to perform VHCF investigations within reasonable testing times due to its high testing frequency Cyclic properties of 18Ni maraging steel sheets with nitrided surface are investigated. The chemical composition is in weight-%: Ni 18%, Co 9%, Mo 5%, Ti 0.5% and rest Fe. Specimens ... |
= 0.1 in the successive test. The exact force for pulling the rod back into vertical alignment is applied with a weight that is connected to the titanium rod’s end with a string via a deflection pulley. In its final vertically aligned position the rod does not touch the end stop by a small margin, which serves as a cri... |
= 0.1 are shown in . Experiments are performed at stress amplitudes between 600 MPa and 450 MPa yielding lifetimes between 9.1 × 106 and 1.9 × 109 cycles. Two specimens were cycled at 450 MPa for more than 1.6 × 109 cycles and did not fail, which is indicated with arrows in S–N data are approximated with a straight lin... |
= 1.52 × 1047 and the exponent to n |
= 14.4. In the investigated regime below 109 |
cycles, the material does not show a fatigue limit.Scatter of data may be quantified using the ratio Tσ of numbers of cycles with 90% fracture probability, N90% and 10% fracture probability, N10% according to the following equation.Fatigue lifetimes measured at all four stress levels are included in the analysis. The i... |
= 2.5 μm and the largest 5.3 μm. The distribution of areaINC is presented in shows crack initiation at an internal inclusion that led to failure in the VHCF regime. The crack propagates perpendicular to the applied tensile stress until it reaches a length between 60 μm and 80 μm. Then the crack leaves the perpendicula... |
= 30 μm to 90 μm.The fish-eye fracture surface shows a distinct difference close to the inclusion and at greater crack lengths (). Close to the inclusion the fracture surface appears granular and homogeneous without steps or secondary cracks. In this area, the crack propagation direction cannot be deduced from the frac... |
= 14 μm and 25 μm. Lower stress amplitudes associated with longer lifetimes show larger sizes of IAAs.The crack-initiating inclusion may be considered as initial crack. The stress intensity range ΔK of an arbitrarily shaped internal crack may be calculated using Eq. With the stress range Δσ and area=areaINC, the stress... |
= 1.3 MPa m1/2. The highest stress intensity range ΔKINC |
= 2.4 MPa m1/2 found for three specimens led to failures between 9 × 106 and 1.8 × 107 |
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