Unlike conventional isotropic materials of steel and concrete. There are no readily available design charts and guidelines to help the structural engineer when it comes to working with composites. Analytical solutions for cracked plates are very limited. Aim of the present work is to provide the structural engineer with data regarding SIF and variation of stress at the crack tip using Finite Element Analysis.FEA addressing plate problem fall under two categories-one involving singularity formulations and other involving paths independent integrals approach .
A combined nite/ discrete element method is presented for modelling composite specimens subjected to dynamic/impact loadings. The main task is set on developing an algorithm for simulation of potential bonding and debonding/delamination phenomena during impact or general dynamicloading conditions. In addition, full fractureanalysis also be performed. The proposed approach adopts a general node to face nonlinear frictional contact algorithm to enforce bonding/debonding constraints between composite plies. The method is also capable of analyzing progressive fracture and fragmentation behaviour as well as potential post cracking interactions caused by the newly created crack sides and segments. A local remeshing technique is adopted every time a new crack is formed, while an overall remeshing is performed anytime a certain criterion of error estimation is violated. The special local remeshing technique is designed to geometrically model an individual crack by splitting the element, separating the failed node, creating new nodes and dividing the neighboring elements to preserve the compatibility conditions. The same procedure is capable of modelling application of bre reinforced polymer (FRP) layers to other engineering structures in order to improve their exible behavior in static and dynamicloading conditions.
that the fracture property of silica/epoxy nanocomposites at different temperatures from −50˚C to 70˚C, and the results showed that the fracture energy was greatly improved at 50 ˚C. Besides the silica/epoxy nanocomposites, many researchers also investigated the fiber reinforced epoxy with silica nanoparticles. Zheng et al.  studied the glass fibers reinforced epoxy/silica nanoparticles composites, and they found that the tensile properties and bending properties of the composites were obviously improved with the increasing of silica nanoparticles. Wang et al.  adopted the “slurry-compounding” process to prepare the epoxy nanocomposites with highly exfoliated clay. The results indicated that Young’s modulus increased monotonically with increasing the clay concentration and fracture toughness reached the maximum at 2.5 wt% of clay. Zhou et al.  analysis the thermal and me- chanical properties of the carbon fiber reinforced clay/epoxy composites. To their analysis, the 2.0 wt% clay filled epoxy showed the highest enhancement in flexural strength. At the same time, the 2.0 wt% systems exhi- bited the highest storage modulus. Ferreira et al.  investigated the fatigue behaviors of Kevlar composites with nanoclay-filled epoxy resin, they found that the filled composites showed tensile fatigue strength 12% higher than unfilled matrices, but in three-point bending the fatigue strength of filled composites was lower. Barbezat et al.  researched the fracture properties of GFRP laminates with nanocomposite epoxy resin matrix, to their researches, the static and dynamicfracture properties of the GFRP laminates were negatively influenced by the modification of the matrix with the organo-silicate. Uddun et al.  analysis that the strength of undirec- tional glass/epoxy composite with silica nanoparticle-enhanced matrix, they found that the silica nanoparticles could dramatically increase the longitudinal compressive strength and moderately increase the longitudinal and transverse tensile strength. Tsai et al.  investigated the mechanical properties of silica nanoparticle rein- forced composites, the results showed that the extent of the silica nanopsrticles were more appreciable in the brittle matrix system rather than in the ductile matrix systems. To the glass fiber/silica/epoxy composites, the in- plane shear strength increased until the nanoparticle loading was up to 10 wt%. Ma et al. - researched the transverse behaviors and compressive behaviors of nanoparticles reinforced composites under high strain rates.
In this section, SIFs are calculated for the real cruciform specimens and then compared with the theoretical solution. 1/8 of each cruciform is simulated with inclined cracks in the central zone. Different values of a i.e. half-size of the crack length, are considered, a = 0.5, 1, 1.5, 2mm. The angle of inclination β considered is the same as for the quasi-infinite plate analysed in previous section. Three different mesh regions can be distinguished with different ele- ment size in the structure. The first one defined is in the central zone with a 0.5 mm size, the second one defined in the arms with 1.5 mm size and the third one in the proximity of the static crack as depicted in Figure 9. For the third mesh refinement, a 4x4mm square is defined surrounding the crack with 1600 elements. The loading applied in this case is on the arms of the cruci- form. Then, for geometry A, 54M P a are applied in each arm, in geometry B, 61M P a and in geometry C, 44.25M P a. These values of load in each arm are responsible for the final fracture of the structure. The values of SIFs obtain with the quasi-infinite plates presented on Table 4 show that the values of K I
Civil engineering structures are usually treated in a static manner, in which the applied forces are in equilibrium and they do not produce any dynamic motion. In the case of impact loading, the applied forces are not in equilibrium; thus the structure is set in motion, hence requiring a dynamicanalysis to determine response. This dynamic situation requires adjusting the design process, especially in cases where the rate of motion is rapid, since the behavior of construction materials, such as steel and concrete, is rate dependent. Extensive researches show that casting reinforced concrete into FRP tubes increases the structural performance of the system when compared to individual components under static conditions. While the FRP tube’s geometry makes it susceptible to buckling and reinforced concrete is easily cracked and damaged. In addition to the strength and confinement that the FRP tube provides, it contains and protects the concrete. Thus it is evident that the containment and protection of the concrete core by the FRP tube makes it suitable for impact resistant design. This
Abstract: Adhesively bonded joints are increasingly being used in joining various structural components made of FRP laminated composites. Adequate understanding of the behavior of adhesively bonded joints is necessary to ensure efficiency, safety and reliability of such joints. While single lap joint has received considerable attention, very little work has been carried out on the double lap joint configuration. The present investigation deals with the staticanalysis of adhesively bonded double lap joint in laminated FRPcomposites using three-dimensional theory of elasticity based finite element method. The finite element model is validated with the theoretical concepts. The double lap joint made of generally orthotropic laminates subjected to longitudinal loading is analyzed. The out-of-plane normal and shear stresses are computed at the interfaces of the adherend and adhesive, and at mid surface of the adhesive for different ply orientations by varying the thickness of adherend is considered for the analysis. It was predicted that when the fiber angle increases the stiffness of the plate in the longitudinal direction decreases and the interlaminar stresses at joint interfaces increases due to the effect of coupling and also the longitudinal displacement increases.
Abstract— The present investigation deals with the staticanalysis of adhesively bonded inner tapered double lap joint in laminated FRPcompositessubjected to Longitudinal loading using three-dimensional theory of elasticity based finite element method. Many researchers studied the influences of various parameters on the failure behaviour on the composites. In those studies, the typical bonding parameters are surface conditions, fillet, bond line thickness, and environmental conditions. In the present study the stresses and deformation characteristics of adhesively bonded inner tapered double lap joint made of generally and especially orthotropic laminates (FRP) subjected to longitudinal and transverse loading for the three different adhesive angles, three different adhesive thicknesses with different fibre angle orientations, i.e. the adhesive angles from 35 0 to 45 0 increased in steps of 5 0 . The variation in
and dynamic loads. Depending on the method used and how the structure is modeled in finite element software the results can vary. Some of the issues and modeling techniques, introduced below, are investigated in this Master’s thesis. Dynamic effects such as resonance frequencies, Gust factors and accelerations are considered. The variation in static results from reaction forces, overturning moments, deflections, and force distributions between concrete cores are investigated with different models. The models are evaluated by different elements and methods, such as construction stage analysis, to study the impact these have on the results. Simplified calculations by hand according to IS (875-partIII), Explanatory handbook of IS(875-partIII)-SP64, Draft code of IS (875-partIII), Thesis references from IIT. The 3D- finite element software used for the analyses is STAAD Pro. V8i(Series-4). From the results it can be observed, when modeling a high-rise building in finite element software, that one model is often not sufficient to cover all different aspects. To see the global behavior, one model can be used, and when studying the detailed results another model with a fine mesh, that have converged, is often needed. The same principle applies when evaluating horizontal and vertical loads, different models or methods are usually needed.
their stress concentrator increases . The stress concentration factor for U notches which support mixed loads is studied in , the authors use the criterion based on the deformation of the average energy density concept. The maximum stress concentration factors in a small rectangular hole rounded edges of orthotropic plate is located on the main axis 1 which is at 67.5º angle about the x axis .In  a flat plate with a hole in the center under the influence of a gradient of linear load was studied, the authors establish an approximate computational model that reduces the required type of load and support the results obtained experimentally and numerically by photo elasticity using the ANSYS® software. Stress concentration in a round bar with a circular arc or V-shaped notch with bending load, tensile load and torsional load is analyzed in . A study to optimize the shape of the fillets and reduce the stress concentration in flat and round bars subjected to axial load, bending load, torsion load or combined loads is performed in .
The purpose of described work was research of fatigue properties of reinforced PP and PC welded joints with various volume ratios of glass fibers. A lot of cyclic tests on a testing machine were performed to obtain relevant data for determin- ing fatigue strength and S-N curves. The results of shear tests prove that the fa- tigue strength of PP reinforced composite weld joints is approximately half to their static strength (one tenth for PC). The fatigue strength of weld joints reaches only one quarter of PP strength and one twentieth of PC strength. The presence of glass fibers inside the polymer matrix doesn’t increase neither the static strength, nor the fatigue strength of weld joints. The fatigue strength of PP Table 3. Parameters of analytical S-N curves shown in Figure 4. The symbol * means that corresponding S-N curve is a constant function equal to the fatigue strength.
Prisms are tested immediately on removal from the water while they are still in wet condition. The bearing surfaces of the supporting and loading rollers are wiped clean, and loose sand or other material removed from the surfaces of specimen where they are to make contact with the rollers. The specimen is then placed in the machine in such a manner that the load is applied to the uppermost surface as cast in the mould, along two lines spaced 13.3cm apart (If the fracture occurs within the middle third of the span, a>133mm, f b = pl/bd 2 .
using IS: 875(Part 3):1987, IS 1893 part 4:2005 and IS 1893 part 1:2002 standards.The relation between the different foundation parameter and corresponding deformation and stress compared by mini tab software. This analysis gives maximum mean result and minimum SN ratio result for best one and evaluate from the modal analysis due to seismic loading a self-supporting steel chimney. There is a need for revising the calculation model for vortex shedding of very slender chimney that is for chimneys with slenderness ratio (height through diameter) above approximately 30.
All design against seismic loads must consider the dynamic nature of the load. However, for simple regular structures, analysis by equivalent linear static methods is often sufficient. This is permitted in most codes of practice for regular, low-to medium-rise buildings. It begins with an estimation of base shear load and its distribution on each story calculated by using formulas given in the code. Linear static method can therefore work well for low to medium-rise buildings without significant coupled lateral-torsional effects, are much less suitable for the method, and require more complex methods to be used in these circumstances.
By setting the displacement rate equal to 2 mm/min, the plain specimens as well as the samples containing both U- notches and crack-like notches were tested under quasi-static tensile loading by using a Shimadzu universal machine. In the un-notched specimens, the local strains were measured during testing via an axial extensometer with gauge length equal to 50 mm. Three different specimens were tested for any geometry/manufacturing configuration that was investigated.
Comparisons between dynamic and static estimates of pile capacity have been reported widely in the literature (Broms 1981,1985; Felenius 1988; Barends 1992; Goble and Likins 1996; Townsend 1996). However, there’s no loading-settlement curve and distribution of friction and toe capacity yet for lightweight concrete pile which driven into soft soil. In this case, the light weight concrete piles (LCP) which has 6 m length and 150x150 mm square in sizes, have been produced and driven into soft soil to evaluate their performance and comparing them with normal concrete (NC) pile.
Schematic of the experimental device used for the dynamicloading is shown in the Fig.2. Coﬀ ee bean is placed on the wood rod and impacted by the falling bar. The bar is made from aluminium alloy. Its length is 200 mm, diameter of the bar is 6 mm. The bar is allowed to fall freely for a pre – selected height. The instrumentation of the bar by the strain gauges (semiconducting, 3 mm in length) enables to record time history of the force at the area of bar – coﬀ ee bean contact. The same instrumentation is used for the supporting wood bar. It enables to record a force transmitted by the coﬀ ee bean to the bar.
In this case, this corresponds to 0.144 mm. Hence, the radial displacement due to the pressure wave is observed to oscillate heavily about this static displacement. At the current instant, the maximum radial deflection is 2.2 times higher than this static displacement. This factor is called the dynamic load factor DLF . Figure 2 also indicates a small precursor vibration in front of the pressure wave, as earlier also calculated for steel pipes . In Fig.3, the pressure wave front has been zoomed in, in order to better visualize how the displacement is oscillating along the length of the pipe. It is observed that over a length of 125 mm, the displacement goes from its maximum to its minimum value.
short coir/glass fibres are mixed with epoxy resin by the simple mechanical stirring. The composites are prepared with three different fibre loading and four different fibre lengths keeping glass fibre content constant (20 wt%) using simple hand lay-up technique. The mixture is poured into various moulds conforming to the requirements of various testing conditions and characterization standards. The detailed composition and designation of the composites are presented in Table 1. The cast of each composite is preserved under a load of about 25 kg for 36 hours before it removed from the mould cavity. Then this cast is post cured in the air for another 36 hours after removing out of the mould. Specimens of appropriate dimension are cut for physical and mechanical tests.
direct drive and other one is back gear drive. Each speed has different belt tension and different gear force, by using basic design formulae we determines the driving force and tabulated in Table 2.1. The stepped hollow spindle is assumed to be simply supported overhang stepped hollow beam and driving forces are considered as point loads. Macaulay’s method (the double integration method) is a technique used in structural analysis to determine the deflection of Euler-Bernoulli beams. There are two bush bearings are used in headstock and these two bearings are mounted on the spindle at different distances. Static stiffness is one of the important parameter of machine tools which should be properly designed to improve the performance of the tools even in dynamic conditions.
It is the responsibility of structural engineers to ensure the built environment that can withstand extreme dynamic actions, such as wind, traffic or earthquake. Structural engineers must understand how the built environment will respond to such dynamic actions. In essence an earthquake resistant structure has to resist the lateral inertial forces in a safe and reliable manner. A structure has to be designed to resist the lateral actions applied to it by the earthquake ground motion. The main objective his study is to understand the requirement of reinforcements for static and dynamicloading on the structure. Here the analysis is carried out for two models with uniform column size for whole building height i.e 450X450mm and two models with varying column size from bottom to top storey i.e from 400X400mm to 300X300mm varying 50 mm per two stories. The analysis and design is carried out using the standard & convenient software package ETABS 2015 and manual designs are carried out to validate the reinforcement obtained from the software. It is observed that the reinforcement required for beam reinforcement required for dynamic behaviour is 5.3% more than that required for staticloading of structure. It is also observed that the reinforcement required for c