Abstract
Motion generation of a four-bar linkage is a type of mechanism synthesis that has a wide range of applications such as a pick-and-place operation in manufacturing. In this research, the use of meta-heuristics for motion generation of a four-bar linkage is demonstrated. Three problems of motion generation were posed as a constrained optimization probably using the weighted sum technique to handle two types of tracking errors. A simple penalty function technique was used to deal with design constraints while three meta-heuristics including differential evolution (DE), self-adaptive differential evolution (JADE) and teaching learning based optimization (TLBO) were employed to solve the problems. Comparative results and the effect of the constraint handling technique are illustrated and discussed.
Address
Wisanu Phukaokaew, Natee Panagant and Sujin Bureerat: Sustainable and Infrastructure Research and Development Center, Department of Mechanical Engineering, Faculty of Engineering, KhonKaen University, KhonKaen City, Thailand
Suwin Sleesongsom:2Department of Aeronautical Engineering, International Academy of Aviation Industry, King Mongkut
Abstract
Numerical modeling of reinforced concrete structures is a difficult engineering problem, primarily because of the material inhomogeneity. The behaviour of a concrete element with reinforcement can be analyzed using, for example, the Barcelona model, which according to the literature, is one of the most suitable models for this purpose. This article compares the experimental data obtained for an orthotropic concrete slab band system with those predicted numerically using Concrete Damage Plasticity model. Abaqus package was used to perform the calculations.
Key Words
reinforced concrete; slabs; numerical modeling; Barcelona model
Address
Department of Strength of Materials and Concrete and Bridge Structures, Kielce University of Technology,
Al. Tysiąclecia Państwa Polskiego 7, 25-314 Kielce, Poland
Abstract
This study investigated the ultimate lateral load capacity of shear walls constructed with several types of structural foam sheathing. Sixteen tests were conducted and the results were compared to the published design values commutated by the manufactures for each test series. The sheathing products included 12.7 mm (1/2 in) SI-Strong, 25.4 mm (1 in) SI-Strong, 12.7 mm (1/2 in) R-Max Thermasheath, and 2 mm (0.078 in) ThermoPly Green. The structural foam sheathing was attached per the manufacturers\' specification to one side of the wood frame for each wall tested. Standard 12.7 mm (1/2 in) gypsum wallboard was screwed to the opposite side of the frame. Simpson HDQ8 tie-down anchors were screwed to the terminal studs at each end of the wall and anchored to the base of the testing apparatus. Both monotonic and cyclic testing following ASTM E564 and ASTM E2126, respectively, were considered. Results from the monotonic tests showed an 11 to 27 percent smaller capacity when compared to the published design values. Likewise, the test results from the cyclic tests showed a 24 to 45 percent smaller capacity than the published design values and did not meet the seismic performance design criteria computation.
Address
Shideh Shadravan : Department of Architecture, University of Oklahoma, 830 Van Vleet Oval, Norman, OK 73019, United States
Chris C. Ramseyer: Department of Civil Engineering and Environmental Science, University of Oklahoma, 202 W. Boyd, Norman, OK 73019, United States
Abstract
The insertion of femoral implants is the most important phase for surgeons, given the characteristics of the cement during its mixing phase, generating residual stresses of thermal origin that increase the different stresses induced in the bone cement. The aim of our study is to determine the different stresses that affect the cement and more particularly at the cement-implant interface for different temperatures, and to make a comparison with the cement at ambient temperature. It was concluded that, there are a large concentration of stresses in the proximal part of the cement. For normal stresses, the bone cement is affected by stresses of tension and compression due to the effect of polymerization and the contraction of the cement.
Key Words
temperature; polymerization; stem–cement interface; stresses
Address
Laboratory of Physics and Mechanical Materials (LMPM), University Djillali Liabes of Sidi Bel Abbes, Algeria
Abstract
This study performed lateral load testing on seventeen wood wall frames in two sections. Section one included eight tests studying structural foam sheathing of shear walls subjected to monotonic loads following the ASTM E564 test method. In this section, the wood frame was sheathed with four different types of structural foam sheathing on one side and gypsum wallboard (GWB) on the opposite side of the wall frame, with Simpson HDQ8 hold down anchors at the terminal studs. Section two included nine tests studying wall constructed with oriented strand board (OSB) only on one side of the wall frame subjected to gradually applied monotonic loads. Three of the OSB walls were tied to the baseplate with Simpson LSTA 9 tie on each stud. From the test results for Section one; the monotonic tests showed an 11 to 27 percent reduction in capacity from the published design values and for Section two; doubling baseplates, reducing anchor bolt spacing, using bearing plate washers and LSTA 9 ties effectively improved the OSB wall capacity. In comparison of sections one and two, it is expected the walls with structural foam sheathing without hold downs and GWB have a lower wall capacity as hold down and GWB improved the capacity.
Address
Shideh Shadravan: Department of Architecture, University of Oklahoma, 830 Van Vleet Oval, Norman, OK 73019, United States
Chris C. Ramseyer, Royce W. Floyd: Department of Civil Engineering and Environmental Science, University of Oklahoma, 202 W. Boyd, Norman, OK 73019, United States
Abstract
In this paper is presented the minimum cost (optimal design) for reinforced concrete circular isolated footings based on an analytic model. This model considers a load and two moments in directions of the X and Y axes, and the pressure has a variation linear, these are the effects that act on the footing. The minimum cost (optimal design) and the Maple program are shown in Flowcharts. Two numerical experiments are shown to obtain the minimum cost design of the two materials that are used for a circular footing supporting an axial load and moments in two directions in accordance to the code of the ACI (American Concrete Institute), and it is compared against the current design (uniform pressure). Also, the same examples are developed through the normal procedure to verify the minimum cost (optimal design) presented in this document, i.e., the equations of moment, bending shear and punching shear are used to check the thickness, and after, the steel areas of the footing are obtained, and it is compared against the current design (uniform pressure). Results section show that the optimal design is more accurate and more economical than to any other model. Therefore, it is concluded that the optimized design model presented in this paper should be used to obtain the minimum cost design for the circular isolated footings.
Address
Department of Civil Engineering, Korean Advanced Institute for Science and Technology,
291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea
Abstract
The sealing cement of total hip arthroplasty is the most widely used binder in orthopedic surgery for anchoring implants to their recipient bones. Nevertheless, this latter remains a fragile material with weak mechanical properties. Inside this material cracks initiate from cavities. These cracks propagate under the effect of fatigue and lead to the failure of this binder and consequently the loosening of the prosthesis. In this context, this work consists to predict the position of cracks initiation and their propagations path using the Extended Finite Element Method (XFEM). The results show that cracks can only be initiated from a sharp edges of an ellipsoidal cavity which the ratio of the minor axis over the major axis is equal to 0.1. A maximum crack length of 19 micro m found for a cavity situated in the proximal zone position under a static loading. All cracks propagate in same(almost) way regardless of the cavity(site of initiation) position and its inclination in the proximal zone.
Key Words
total hip replacement; XFEM; orthopedic cement; cavity; damage; crack propagation
Address
Bachir Gasmi, Sahli Abderrahmene, Benbarek Smail and Aour Benaoumeur: Department of Mechanical Engineering, National Polytechnic School of Oran, BP1523 El Mnaour 31000, Oran, Algeria
Benbarek Smail :Laboratory of Physics and Mechanical Materials (LMPM), University Djillali Liabes of Sidi Belabbes, BP89 Cite Larbi ben Mhidi,22000n Algeria
Abstract
A low computational cost semi-analytical method is developed, based on eigenfunction expansion, to study the vibration of rectangular plates subjected to a series of moving sprung masses, representing a bridge deck under multiple vehicle or train moving loads. The dynamic effects of the suspension system are taken into account by using flexible connections between the moving masses and the base structure. The accuracy of the proposed method in predicting the dynamic response of a rectangular plate subjected to a series of moving sprung masses is demonstrated compared to the conventional rigid moving mass models. It is shown that the proposed method can considerably improve the computational efficiency of the conventional methods by eliminating a large number of time-varying components in the coupled Ordinary Differential Equations (ODEs) matrices. The dynamic behaviour of the system is then investigated by performing a comprehensive parametric study on the Dynamic Amplification Factor (DAF) of the moving loads using different design parameters. The results indicate that ignoring the flexibility of the suspension system in both moving force and moving mass models may lead to substantially underestimated DAF predictions and therefore unsafe design solutions. This highlights the significance of taking into account the stiffness of the suspension system for accurate estimation of the plate maximum dynamic response in practical applications.
Key Words
vibration analysis; moving mass; maximum dynamic response; multiple vehicular load; sprung mass
Address
Ali Nikkhoo, Soheil Asili, Shabnam Sadigh, and Hossein Karegar: Department of Civil Engineering, University of Science and Culture, Tehran, Iran
Iman Hajirasouliha :Department of Civil and Structural Engineering, University of Sheffield, Sheffield, UK
