Shear lag ratio is introduced to measure the magnitude of shear lag effect. Shearlag analysis of a hybrid, unidirectional composite. Goland and reissner 6 and oplinger 7 accounted for adherend bending deflections to predict the peel stress in the adhesive. Moreover, most existing theories neglect shear lag in the webs and, although they are acceptable for bridge decks that normally have flanges wider than webs, they may not be.
For a laminated plate incorporating throughthickness fibers, highlights are. In the strengthbased theories, the original shearlag theory cox, 1952 has been widely adopted to obtain the shear stress distribution at the fibrematrix interface. The use of a flow rule to govern the matrix deformation in this model differs from. We measure uniaxial strain fields in the vicinity of edges and wrinkles in graphene prepared by chemical vapor deposition cvd, by combining microscopy techniques and local vibrational characterization. Adhesive shear strain and shear stress shear strain in adhesive g a is due to differential stretchingdisplacement u i and u o of adherends adhesive shear stress t a is g ag a where g a is the adhesive shear modulus take first derivative w. From the brief survey the following conclusions can be made. Investigation of shear lag effect in highrise buildings. Tsai, oplinger, and morton 8 provided a correction for adherend shear. Analytical approach for shear lag in welded tension members.
Stress analysis of adhesive bonded joints under inplane. Generalized shearlag model for load transfer in sical. The shear lag theory published by volkersen in 193857 assumes that the adherends only carry tensile stresses and the adhesiveonly shear stresses. Shear lag model the strength of mmc reinforced with cylindrical whiskers was analyzed considering the load transfer from matrix to reinforcement using the shear lag model. Recommendations for shear lag factors for longitudinally welded tension members, engineering journal, american institute of steel construction, vol.
Dartmouthx the engineering of structures around us 94,385 views 9. Some of the flanged section is not joined to the gusset. More pronounced in shells of shallow section than in shells in deep section. Pdf shear lag models for stress transfer from an elastic matrix to a. In a structure if two members are joined via a flanged member like anglesection or csection or isection for sustaining tensile or compressive load we dont connect all the the crosssection or component.
Shear lag analysis of a hybrid, unidirectional composite with fiber damage james g. The process of starting from elasticity theory and deriving various shearlag models by successive approximations can be used to categorize most. Assuming a shearlag model, the platelets support longitudinal stresses a. Introduction the elastic response of composite systems to externally applied stress can be predicted by eshelby type models, which are valid for ellipsoidal inclusions 1,2,3,4, or by shear lag sl type models. Recommendations for shear lag factors for longitudinally. Mechanism in isection beam when exposed to bending around strong axis and simply supported, deformation is exaggerated the mechanism is sketched in figure 2 for a simply supported transverse loaded i. However, there have been relatively few studies on shear lag in wall structures. Shearlag model for failure simulations of unidirectional. It shows a plan cross section of a building with a moment induced because of lateral load. A shearlag model for a broken fiber embedded in a composite with.
Interfacial stress transfer in a graphene monolayer nanocomposite. Much more important in wings than in fuselage if the basic method of construction is similar the effect of sheet panel. These strain fields have magnitudes of several tenths of a percent and extend across micrometer distances. Shear lag provisions for welded members were introduced into the specifications primarily because of a large welded hanger plate failure. It shows the theoretical and the real distribution of axial stresses in peripheral columns. An extended shear lag model is developed to predict the frictional response of extensible strips the analysis resembles that obtained when shear lag theory is applied to lap shear joints experiencing adhesive layer plasticity acknowledgement the authors would like to. A check for the shear lag correction can be made if desired. Shear lag effect is relevant to any slender box element that is loaded laterally such as airplane wing structures and box girder bridges. Once the method for calculating the theoretical shear lag factor was determined, the empirically based shear lag factors could be used to determine reasonable values for the alpha factor and angle. Shear lag in shearcore walls journal of structural. Thus far, these techniques, with the exception of landis and mcmeeking 1998, assume that the. The authors propose an analytical approach for calculating the reduction in strength of steel tension mem bers due to shear lag effects. This simple theory also predicts zero shear stress and zero shear strain in the flange. The process of starting from elasticity theory and deriving various shear lag models by successive approximations can be used to categorize most planar shear lag models in the literature and rank them by expected accuracy.
Less than one value of shear lag ratio describes the negative shear lag. It is the ratio of stress of maximum stress at the corner side of the flange panel to the middle of the panel where stress is least. Dharani clemson university clemson, south carolina prepbed for langley research center under grant nsg 1297 national aeronautics and space administration scientific and technical information branch 1983. Aalborg university denmark evaluation of shear lag in standard hisections 4 figure 2. Shear lag occurs not only in bridge decks and framed tubes, but also in shear core walls.
In this paper, a new methodology is proposed for the definition and subsequent experimental measurement of. Dynamic problems are solved using beam theory and shear lag approximations, and also fem. Pure axial action in adherends and pure shear in adhesive. Stress distributions were considered at both the elastic and ultimate load levels. Can also use horizontal and diagonal board sheathing, gypsum panels, fiberboard, lath and plaster, and others blocked shear walls most common. According to this approach, it is assumed that the transverse ply does not carry any axial load in the crackplane, while away from the crack a part of this load is transferred back to the transverse ply through axial shear. Constant shear across adhesive layer thickness t 3. The optimal, shear lag and the hedgepethlike, shear lag analyses were applied to several sample calculations. Pdf a differential equation describes the average axial stress. Analytical approach for shear lag in welded tension members1 georges abisaad and dominique bauer abstract. As early as the 1930s researches had been conducted to study the shear lag effect in box beams. Shear lag effects in steel tension members, engineering journal, american institute of steel construction, vol. Correlating stiffness and shear lag behavior with brace. The approach is based on an assumed distribution of forces along inclined lines in the.
Shear resistance of the sheet is further reduced when the sheet buckles, and the shear lag effect l3 increased. Mtehods of analysis and failure predictions for adhesively. In the strengthbased theories, the original shear lag theory cox, 1952 has been widely adopted to obtain the shear stress distribution at the. Shear lag models in this section the basic shear lag governing equations are developed. Fracture mechanics of unidirectional composites using the shear.
Pdf a new shear lag sl type model for stress transfer in a composite with cylindrical fibres is derived. Arch 331 note set 18 f2015abn 307 steel design notation. Linear elastic behaviour of materials e 1, t 1, b 1 e 2, t 2, b 2 g 3, t 3, b 3 p 1 p 2 p 3 p 4 luftfahrtforschung, vol. A new analytical model based on the shear lag theory is developed for stress analysis and prediction of the steady state creep deformation of short fiber composites subjected to an applied axial load. In a structure if two members are joined via a flanged member like anglesection or csection or isection for sustaining tensile load we dont connect all the the crosssection or component. The behaviour of a discontinuous flake in a matrix can be modelled using shear lag theory in which it. On the use of shearlag methods for analysis of stress.
For a given problem eg simple beam, uniform load, box cross section. Shear lag effect in a tall building can be demonstrated as shown in fig. This ratio tells the effect of shear lag in the panel. The nonlinear shear lag model remarkably captures these strain fields in terms of the.
The dierences between shear lag models arise as a result of dierences in the assumed matrix constitutive behavior elastic, plastic, creeping, and the interface behavior weakly bonded versus well bonded. Shear lag effects in steel tension members american. Adhesive joints theory and use of innovative joints. Definition and measurement of the shearlag parameter. Instead of the vanishing chordwise variation of the sheet displacements of elementary beam theory, we now assume a parabolic variation. Physical meaning of shear lag engineering stack exchange. On the use of planar shearlag methods for stresstransfer. Lateral forceresisting systems braced frame, shear wall, and momentresisting frame duration. Hartsmith 3, 4 extended the shear lag theory that was presented by volkersen 5 to include adhesive plasticity. These values were determined using the least squares method on the theoretical and empirically based shear lag. The shear lag theory provides a simple onedimensional solution to the above boundary value problem bvp. I cant speak to fiberreinforced composites, but the general concept of shear lag is summed up in the aisc 36010 specification, commentary section d3 as such shear lag is a concept used to account for uneven stress distribution in connected members where some but not all of their elements flange, web, leg, etc. Carlos montestruque 1 shear lag shear lag thin sheet structures under loading conditions that produce characteristically large and nonuniform axial stringer stress.
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