Ahmad, M.I.M., Curiel-Sosa, J.L., Akbar, M. et al. (1 more author) (2018) Numerical inspection based on **quasi**-**static** **analysis** using Rousselier damage model for aluminium wingbox aircraft structure. In: Journal of Physics: Conference Series. Modern Practice in Stress and Vibration **Analysis** (MPSVA) 2018, 02-04 Jul 2018, Cambridge, United

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Through study and **analysis**, Rear Under-Run Protection devices protect road users such as pedestrians and cyclists from slipping from the rear under the wheels of trucks and trailers. The basic objective is to improve the safety of the car and the occupants by designing the RUPD. The choice of material and the structural design are the two major factors for **quasi**-**static** **analysis** of RUPD in sequential

In this paper we propose the estimation of the characteristic impedance and the effective dielectric constant of microstrip line using **quasi** **static** **analysis** and performances are predicted using theoretical **analysis**. Numerically efficient and accurate formulae based on the **quasi** **static** method for the **analysis** of microstrip line structures are presented. The **analysis** formulas for microstrip line are derived and verified with Matlab. Characteristic Impedance of microstrip line for different normalized strip width as well as for different effective permittivity is under consideration in this work.

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Abstract— In this paper, the effect of disturbance factor on the stability of rock slopes in the **quasi** **static** **analysis** was investigated. For this purpose, four slopes with dips of 30, 45, 60 and 75 degrees were modeled by Phase2 software in the **quasi** **static** case and the effect of rock disturbance factor (D) was investigated on the slope stability. The stability of slopes with earthquake acceleration of 0.1g, 0.2g and 0.3g were determined using the critical strength reduction factor (SRF) of slopes. The results indicate that in the **quasi** **static** **analysis**, the excavation percentage has a higher effect than D parameter in reducing the SRF. Also, the SRF reduction rate shows disorganizations which is because the joints are located in the direction of the earthquake acceleration. Moreover, by increasing the D parameter, the earthquake acceleration effect on the SRF has decreased.

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3. SIMULATION OF SLAMMING LOADS The applicability of FE **analysis** as a tool to predict sea loads based on “Reverse Engineering” procedures has been discussed and tested in [5] as well as **quasi**-**static** **analysis** procedures for normal operating conditions without slamming. In contrast to similar studies, where calibration factors between the applied loads and strains are extracted from a hypothetical loading condition applied to the FE model, [6], [7] and [8], sea trials data, namely wave height, bow and CG vertical accelerations, pitch and relative bow height records, can be used to develop a **quasi**-**static** load case for input to the FE model. The numerical strains and trials strains are then compared. Slamming loads are usually dealt with in the same manner, i.e., calibration factors are used to convert trials strains to an “equivalent- hypothetical” **static** wave loading model except for the work done in [9] in which a complementary slam load with approximate wave loading condition, based on trials measurement for wave length and height, was used. The calibration factors methodology, based only on the equivalent **static** wave approach, in treating slamming loads does not provide any information about slamming location nor spatial distribution which is of great importance for local **analysis**. As an alternative, the procedure discussed in [5] will be applied in which the **quasi**-**static** sinusoidal wave loads are not exaggerated to produce the large slam response. Instead, the impact loads are dealt with as “add-on” complementary loads which will be changed systematically until a best match between FE strains and trials strains is achieved. Therefore, the loading model to be fed as input to the FE model should contain basic information about the load application area, magnitude and distribution.

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ultimate strength assessment under combined longitudinal compression and edge shear loading. The model ge- ometry and material parameters are presented in Section 2.1 while the prescribed boundary conditions are de- scribed in Section 2.2. Each of the following analyses steps are presented in Section 2.3: i buckling **analysis** for initial imperfection estimation based on the first response mode, ii **quasi**-**static** **analysis** of the rigid body inden- tation to simulate the damage and the spring back response, iii **quasi**-**static** analyses subjected to shear loading taking into account the initial imperfections and the residual stresses from indentation followed by iv the modi- fied Riks method Crisfield 1981 analyses applying compression to estimate the ultimate strength under com- bined loading. For the case with no indentation damage i.e. only initial imperfections step ii is disregarded. 2.1 Model definition

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mechanism and an axial restraint of the connection member. The displacement mode shapes of the elastic displacement mode of the connection, the elastic displacement mode of the beam and the plastic large displacement mode are used to analyze the overall elastic-plastic behavior. The uncoupled mode shapes allow to separately determining the elastic and plastic effects in the **quasi**-**static** **analysis**. The total energy of flexural and membrane behavior is derived by using the displacement of the model corresponding to the mode shapes. The structural response is analyzed based on a consideration of the minimum potential energy of the beam system. The pressure load-displacement response is solved through a trial and error process.

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Fig. 5(a) and Fig. 5(b) shows the capacitance versus a/b for Alumina and Roggers Substrate respectively. From figure it is clear that the capacitance of FCPW is sensitive to change in aspect ratio. From **quasi** **static** **analysis** it is seen that Capacitance decreases with increasing a/b. And the slope of curve almost remains same for all heights. As height of the substrate increases, its capacitance decreases.

The next set of experiments was conducted in order to demonstrate the influence of the memory size used of the look-up tables on the pos- sible energy savings with the **quasi**-**static** voltage scaling. For this ex- periment we have used three sets of tasks graphs with 20, 50, and 100 tasks, respectively. Fig. 7 shows the percentage deviation of energy savings with respect to an ideal online VS as a function of the memory size. For example, in order to obtain a deviation below 0.5%, a memory of 40kB is needed for systems consisting of 100 tasks. For the same quality, 20 and 8kB are needed for 50 and 20 tasks, respectively. It is interesting to observe that with a small penalty in the energy savings, the required memory decreases almost by half. For instance, for 100 tasks, the **quasi**-**static** algorithm achieves 2% deviation relative to the ideal algorithm with a memory of only 24kB. It is important to note, that in all the performed experiments we have taken into consideration the energy overhead due to the memories. This overheads have been calculated based on the energy values raported in [1, 16] in the case of SRAM memories.

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Fig. 4. Total bruise volume (i.e. in **static** test volume of two bruise spots formed at the pear surface and volume of one bruise spot in dynamic test) plotted against the loading energy. The symbols represent data from the individual tests. Open circles denote the results from the **quasi**-**static** tests, full circles denote the results from dynamic tests. a) dynamic test represented by double-stroke by spherical indentor, b) dynamic test represented by simple stroke by flat indentor. The equations in the figures are used for chara- cteristic HL-values in **quasi**-**static** tests (quadratic equation) and for dynamical tests (linear equation only in case b)

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In order to estimate fatigue damage, firstly the stress states damaging the assumed critical locations must be considered. In general the magnitude of the forces experienced by water distribution pipes, certainly grey cast iron pipes, is insufficient to cause localised plastic deformations. Further, corrosion phenomena, such as graphitisation, result in a slight tendency for the material to embrittle. These considerations suggest that stress **analysis** can be carried out using a simple linear-elastic constitutive law to model the material behaviour. Consider now the cylindrical pipe sketched in Figure 2b and assume that it subjected to an internal, p i (t), and external, p e (t), time-variable pressure, the adopted frame of reference

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century, and critical stress intensity factor is usually used to evaluate the structure safety. When the structure is under a **static** or **quasi**-**static** load case, there is no doubt to do so. Nonetheless, even if stress intensity factor is less than its threshold value, cyclic load or sustaining load can still make the crack propagate. Pressure oscillation happens to steam generator tubes time to time, so fatigue crack propagation **analysis** must be done for steam generator tubes.

This project investigated the crash energy absorption in the study of cylindrical tube under axial, lateral loading and multilayer cylindrical tube under lateral loading **quasi** statically to determine the important parameters by performing compression test.

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This study is to observe the W-shape beam (crash barrier) subject to **quasi**-**static** loading. The specimen is cut from crash barrier, W-shape with 50mm width as available in laboratory. The total specimen is 11. The lateral loading is applied with various speed of compression, ranging from 5mm/min – 30mm/min. The deforming modes are captured by digital \and video cameras. The load-displacement is obtained from Instron Universal testing Machine will be compared for various rate of loading. The energy absorbed is calculated by measuring the area under the curve.

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BIE methods are among the most efficient numerical methods which depends strongly on finding the fundamental solutions of the governing homogenous PDEs, especially in the BEM. Therefore, many efforts have been devoted on finding the fundamental solutions for different cases of the problem. The first set of fundamental solutions for saturated media has been introduced by Cleary [3]. Then, several researches have been published on the fundamental solutions for different phenomena of saturated porous media such as deformation and heat conduction. In contrast, the fundamental solutions for unsaturated media have been published recently. Gatmiri and Jabbari derived the first **static** and **quasi**-**static** fundamental solutions of the problem in both Laplace and time domains [4], [5]. Later, Maghoul et al. presented coupled thermo-hydro-mechanical fundamental solutions for the same **quasi**-**static** loading condition of the unsaturated soil for two and three-dimensional time domains [6]. Ashayeri et al. introduced fundamental solutions for the dynamic problem in both 2D and 3D cases. A similar problem has been studied by Li and Schanz [7]. Ghorbani et al [8] studied the non-linear behavior of the solid skeleton of the soil in the **analysis** of multiphase unsaturated soils when subjected to both **static** and dynamic loading. Igumnov et al [9] considered wave propagation in fully and partially saturated porous media with examples of two-components and three-components. Igumnov et al [10] deduced the solution of a finite one-dimensional column with Neumann and Dirichlet boundary conditions based on the theory of mixture.

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of j(y) decreases, cos α decreases according to eq. (23), and hence α increases: the front reorients as we expect. Eventually however a local minimum of j(y) is reached (see, e.g., ﬁg. 2). Moving downwards below this, according to eq. (23), α starts to decrease again. This then signals a change in the front shape in ﬁg. 4 from convex to concave. It is known, however (see sect. 1 and also [18]) that con- cave shapes are problematic in the pressure-driven growth model, since they have a tendency to focus down into sharp concave corners. It is valid to ask therefore how it is possible for a concavity to be sustained indeﬁnitely in a **quasi**-**static** solution. The reason turns out to be that individual elements of front only spend a ﬁnite amount of time in the concave region: they migrate into the con- cavity at one vertical location and then migrate out of it again at another vertical location before they have shrunk down to a sharp corner. The proof of this result is given below.

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properties in all direction and fibrous material with high tensile strength fibers oriented in a common direction. O'dogherty et al. (1995) with studied straw wheat reported that the stem internode position for the fourth stage of maturity had some significant effects on the strength and elastic module. Skubize (2001) used mechanical and x-ray methods to determine the mechanical properties of the stems of winter rape varieties, and found that the character of the changes in the rigidity, bending stress, **static** shear energy, and the dynamic shear energy properties over the length of the stem was best expressed by a quadratic polynomial equation. Ince et al. (2005) stated that the specific shearing energy of sunflower stalk residue decreased towards the upper regions. Also reported that the different physico-mechanical properties at different heights due to cross-sectional heterogeneity and mechanical properties are also different at different height of plant stalk (Ince et al., 2005). Yiljep and Mohammed (2005) reported the high correlation between knife velocity, cutting energy requirement and cutting efficiency. Also they estimated the minimum cutting energy requirements for 20 and 120 mm stalk cutting height, 7.87 and 12.55 N m respectively, at corresponding knife velocities of 2.91 and 3.54 m s -1 (Yiljep and Mohammed, 2005). Tabatabaeefar and Borgheie (2006) studied shear cutting of four rice variety and stated that the dynamic shearing strength decreased from 234.4 to 137.4 Kpa with an increase in blade cutting angle speed from 0.6 to 1.5 m s -1 . Nazari Galedar et al. (2008) reported that the shearing energy of alfalfa stem decreased towards the upper regions of stem. Tavakoli et al. (2009) studied on the effect of moisture content levels 10%, 15% and 20% wet base, three loading rates 5, 10 and 15 mm min -1 and three internodes first, second and third internode, reported that both the shear strength and shearing energy increased with an increase in moisture content and loading rate and towards the third internode position. Taghijarah et al. (2011) measured shear strength and specific shearing energy of sugar cane stalks on 5, 10 and 15 mm min -1 loading rate, found that loading rate had a significant effect on the shear strength and specific shearing energy of the stalk and reported with increasing loading rate, the shear strength and

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This paper presents the effect of round hole on the peak load and energy absorption of circular tube structure. Circular tube made of mild steel was used to observe modes of deformation and load-displacement characteristics during experiment. Axial crushing tests were carried out on the tubes under **quasi**-**static** loading condition. The load-displacement characteristics of tested curves are presented. Experimental results of round hole with 10mm diameter at the middle of samples showed 10.45% decrease of peak load than without hole. Energy absorption experimentally slightly decreased than without hole. It has been found the diameter of round hole has a considerable effect of the collapsed characteristics of tubes. Comparison of theoretical and experimental of crushingbehavior of circular tube under axial **quasi**- **static** loading is presented.

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In this study, AA2519 alloy was initially processed by multi axial forging (MAF) at room and cryogenic temperatures. Subsequently, the microstruc- ture and the mechanical behavior of the processed samples under **quasi**-**static** loading were investigated to determine the influence of cryogenic forging on alloys’ subgrains dimensions, grain boundaries interactions, strength, ductili- ty and toughness. In addition, the failure mechanisms at the tensile rupture surfaces were characterized using scanning electron microscope (SEM). The results show significant improvements in the strength, ductility and tough- ness of the alloy as a result of the cryogenic MAF process. The formation of nanoscale crystallite microstructure, heavily deformed grains with high den- sity of grain boundaries and second phase breakage to finer particles were characterized as the main reasons for the increase in the mechanical proper- ties of the cryogenic forged samples. The cryogenic processing of the alloy resulted in the formation of an ultrafine grained material with tensile strength and toughness that are ~41% and ~80% higher respectively after 2 cycles MAF when compared with the materials processed at ambient temperature. The fractography **analysis** on the tested materials shows a substantial duc- tility improvement in the cryoforged (CF) samples when compared to the room temperature forged (RTF) samples which is in alignment with their stress-strain profiles. However, extended forging at higher cycles than 2 cycles led only to increase in strength at the expense of ductility for both the CF and RTF samples.

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