FINITE ELEMENT MODELING AND FABRICATION OF AN SMA-SMP SHAPE MEMORY COMPOSITE ACTUATOR

Shape memory alloys and polymers have been extensively researched recently because of their unique ability to recover large deformations. Shape memory polymers (SMPs) are able to recover large deformations compared to shape memory alloys (SMAs), although SMAs have higher strength and are able to generate more stress during recovery. This project focuses on procedure for fabrication and Finite Element Modeling (FEM) of a shape memory composite actuator. First, SMP was characterized to reveal its mechanical properties. Specifically, glass transition temperature, the effects of temperature and strain rate on compressive response and recovery properties of shape memory polymer were studied. Then, shape memory properties of a NiTi wire, including transformation temperatures and stress generation, were investigated. SMC actuator was fabricated by using epoxy based SMP and NiTi SMA wire. Experimental tests confirmed the reversible behavior of fabricated shape memory composites. The Finite Element Method was used to model the shape memory composite by using a pre-written subroutine for SMA and defining the linear elastic and plastic properties of SMP. ABQUS software was used to simulate shape memory behavior. Beside the animated model in ABAQUS, constitutive models for SMA and SMP were also developed in MATLAB® by using the material properties obtained from experiments. The results of FEM simulation of SMC were found to be in good agreement with experimental results

Numerical Evaluation of the Lateral Behavior of Vertical and Battered Pile Group Foundations Using 3-D Finite Element Modeling

The design of pile foundations to resist lateral loads is essential in offshore structures and bridge foundations. The lateral behavior of piles has been studied in the past by experimental investigations coupled with analytical and numerical methods. The problem is complex due to the nonlinearities from soil behavior, gap formation, and pile-soil-pile interaction in pile groups (or the group effect). In this work, the finite element (FE) modeling was used to study the lateral behavior of pile groups. The FE method is robust and allows incorporating the necessary aspects for studying the behavior of pile groups. The nonlinear material behavior was incorporated using nonlinear constitutive models. The pile-soil interface was modeled using the zero-thickness surface-surface interaction, which provided the capability for modeling the gap behind the piles, and the transfer of interface normal and frictional stresses. The group interaction was facilitated thru the interaction of stress fields around the piles, and by the continuity of the FE mesh. The lateral behavior of three pile group (PG) configurations (vertical, battered, mixed) with a similar number of piles were evaluated under static and dynamic loading. In the static analysis, the case study of the M19 pier foundation field test was used to verify the FE models. A parametric investigation for the effect of pile spacing and clay soil type was performed. The results showed that the lateral stiffness of the battered and mixed PGs was significantly higher than the vertical PG (+120%, +50%, respectively). The lateral load was found unevenly distributed among the piles in all PGs, and the exterior piles carried 1.5-2% higher load than the interior piles. The influence of the group effect vanished at pile spacings greater than 5D (D is pile width). Also, the influence of pile spacing was more prominent along the load direction. In the dynamic analysis, the PGs behavior was evaluated in barge impact simulations. The results showed that the battered and mixed PGs had similar and large lateral stiffness, which resulted in limited pile cap displacement and large deformation in the barge bow. The weak lateral stiffness of the vertical PG allowed the development of significantly larger impact force and pile cap displacement compared to the battered and mixed PG

Intifada 3.0? Cyber colonialism and Palestinian resistance

Palestine “exists” on Google and increasingly in various other “virtual” ways. But are “Palestine” on Google or the acquisition of the google.ps domain name in 2009 examples of political resistance on the internet? For Palestinian politicians, virtual presence has historical significance. Consider, for example, the Ministry of Telecommunications and Information Technology’s (MTIT) suggestion that “ICTs information and communications technology] contribute directly to the national goal of establishing and building an independent state.”3 Within that context, Sabri Saydam, adviser to Palestinian Authority (PA) president Mahmoud Abbas and a former MTIT minister himself, posited Google’s 2013 move as “a step towards...liberation.” 4 For Israeli politicians, as quoted above, the emergence of (a virtual) “Palestine” poses ideological and practical dangers. Both camps ascribe power to the internet. Their only disagreement is over the ends to which the internet is a means: The internet is a threat to the existence of the state of Israel or a step toward a future state. At heart, however, both views are a form of technological determinism. They remove the internet from human, historical, and geopolitical contexts, and posit it as agent of political, social, or economic change. We contend that neither position is valid

Deactivation of tannins in raisin stalk by polyethylene glycol-600: Effect on degradation and gas production in vitro

An experiment was conducted to assess the effects of polyethylene glycol (PEG-6000) and urea on dry and organic matter digestibility (IVDMD and IVOMD, respectively) and gas production in vitro. Raisin stalk contained 8.6% crude protein, 85% dry matter, 7% ash, 13.95% total extractable phenol (TEPH) and 2.13% total extractable tannin (TET). The experimental treatments were: raisin with no supplementation as control (C); supplemented with 3% urea (U 3%), 5% urea (U 5%) or 3% urea plus 5% PEG (U-PEG) per DM. The rumen liquor fluid was obtained from two ruminal-cannulated fat-tailed sheep. TEPH and TET were determined and in vitro incubation was also conducted. The results indicated that the PEG increased IVOMD and IVDMD. The gas produced from time 0 to 3 and 3 to 6 h of incubation were significantly higher in PEG treatment than that of other groups (P < 0.05). The U-PEG treatment increased the total gas production in 96 h, but it was not statistically significant (P = 0.06) Gas production in 96 h incubation using 300 mg fresh sample was significantly higher than 200 mg sample (P < 0.05). It is concluded that the negative effect of tannin on DM and OM digestibility and also gas production of raisin stalk in vitro could be alleviated by PEG treatment.Key words: Raisin stalk, tannin, polyethylene glycol (PEG), urea, gas production, digestibility, in vitro