Papers by Keyword: Tension

Abstract: Rivet joints are used in structures that can withstand large vibration and repeated loads, as well as for connecting parts made of non-weldable materials and not allowing welding due toheating parts. In addition, riveted connections widely used to connect seversl parts in one package. In instrument making, rivet connections are used more often than in mechanical engineering. Among all constructions applied in the technique, constructions with equal resistance are considered optimal. Thus, equal stresses are created in any element of these constructions and even at any point of each element. When the value of these stresses is equal to the allowable stress, the mass of the structure is minimal. With a theoretically correct choice of the optimal elements of the connection, its destruction should occur along all of the above sections simultaneously. Riveted connections must be of equal strength. This means that the calculation must ensure the strength of the rivets against shear and crushing, the walls of the holes for the rivets-against crushing, thr parts connected along weakened sections-against tension, and their edges-against shear (puncture). The issue of design of riveted joint with equal resistance is considered. A formula has been obtained that indicates that the diameter of the rivet depends on the thickness, width and number of rivets of the connected parts (sheets).

Abstract: The paper shows results of studying the effect of zero-to-tension cycling, with an amplitude approximately corresponding to the conventional yield strength, and subsequent static elastic tension along the same direction on the behavior of magnetostriction and differential magnetic permeability of low-alloy structural 08G2B steel. The behavior of the studied magnetic characteristics under static tension confirms the inference that the level of residual compressive stresses induced by cyclic preloading increases along the axis of cyclic tension.

Abstract: Investigation presents an experimental study of mechanical properties of hybrid bio-composites made from man-made cellulose fibres and soft wood microfiller embedded into polypropylene homopolymer matrix at different weight contents. Mechanical properties such as elastic modulus, tensile strength, and impact resistance of the reinforced composites determined for various total weight contents of both biobased fillers were used as the design parameters. The problem was solved by planning the experiments and response surfaces method. The results demonstrate that using the both filler types enhance the mechanical properties. The tensile modulus increases by ~115%. The bio-composite with the highest weight content of man-made cellulose fibres and the lowest content of soft wood microfibers possesses maximum tensile strength (more 66 MPa). Addition of man-made cellulose fibres demonstrate a significant influence on the impact resistance of the investigated composites.

Abstract: The paper analyzes the influence of tension (dam) on the stress-strain stain and plasticity margin. For the analysis, a model of continuous rolling in three adjacent stands was developed using the Deform 3D software. The adequacy of the model was confirmed by comparing the experimental data from the small-section wire mill 150 and the simulation results. Further, a computational experiment was planned to identify the effect of mismatched of rolling speeds on stress-strain stain. It is shown that for small deviations of rolling speed from the matched mode, there is no significant change in the reserve plasticity along the specific trajectory of the particles movement.

Abstract: Here we explored the chemical durability of glass fiber-reinforced polymer (GFRP) bars under load. Three batches of ribbed GFRP bar specimens were fabricated using binder matrices: ED-22+isomethyltetrahydrophthalic anhydride (iso-MTGFA), ED-22+Ethal-450 and NPPN-631+ iso-MTGFA. As the reinforcing filler, we used an EC17 glass roving (for all the specimen batches). The specimens of each batch were aged in a 1 N alkaline NaOH solution at 60 °C for 2000 hrs. The ageing was performed under a 300 MPa load (30% of the failure stress). The tensile strength of the specimens from each batch following ageing was measured. The tensile test results demonstrated that that the strength loss of the specimens following chemical ageing was 58.9% for batch 1 based on ED-22+iso-MTGFA, 6.6% for batch 2 based on ED-22+Ethal-450, and 33.6% for batch 3 based on NPPN-631 + iso-MTGFA. The specimens of batch 2 based on ED-22+Ethal-450 exhibited the greatest resistance to the NaOH alkaline solution (a strength loss of 6.6%).

Abstract: A model of the magnitude of the stresses of the tip of the cutting blades of a thread-forming tool based on the theory of a homogeneous body is proposed. A model of second-order materials is considered. A description of the stress state is given using two stress tensors independent of each other.

Abstract: Tensile, compressive and flexural (3-point bending) tests are performed on electromechanical universal testing machine (Zwick/Roell 250kN) to determine mechanical characteristics of an aluminium hybrid composite fabricated through stir casting process at different rates of quasi-static loadings in room temperature 25°C. Influence of heat treatment (annealing) is observed on the material properties. After annealing, the tensile, compressive and flexural strengths decrease while ductility, malleability and bending capability of the composite increase. Bending tests are conducted at different crosshead speeds (1-100mm/min) to study its effects on flexural stresses. It is found that the specimen geometry affects the stress-strain behaviour of the composite.

Abstract: The paper analyzes the influence of tension (dam) on the technological parameters of the rolling process (spreading, force and rolling torque). For the analysis, a model of continuous rolling in three adjacent stands was developed, using the Deform 3D software. The adequacy of the model was confirmed by comparing the experimental data from the small-section wire mill 150 and the simulation results. The error in determining the forming was 0.4%, and in determining the power parameters was 11%. Further, a computational experiment was planned, to identify the effect of mismatched of rolling speeds on technological parameters. According to the results of calculations, graphs of changes in technological parameters were constructed. It is established that, even small deviations of rolling speed from the matched mode lead to significant changes in technological parameters.

Abstract: The paper deals with possible ways of defining the material model of fibre reinforced concrete as a material for structural design. The material model is a tool that can be used to describe response of material to the applied load. It usually includes several different parameters: strengths, ultimate deflections, deformation modules, fracture energy, etc. The paper deals with the problematic phases of tests that are necessary to create a material model, but which may not always provide relevant data. Due to the nature of the material (a fibre reinforced composite with a relatively brittle matrix), it is necessary to analyse separately the behaviour of the material before and after cracks when creating the material model.

Abstract: The subject of the article is the introduction of the results of the first series of tests of precast reinforced concrete pillars. These are the pillars simulating parts of walls that can, for example, form in the precast wall of residential buildings after an opening has been carved. The pillars are variously reinforced: from the simple reinforcement with wire mesh, to the reinforcement with standard reinforcement bars. Depending on the type of reinforcement and the type of loading, the deformation and tension of the individual pillars are studied. All of the pillars failed due to local compression of the concrete, a transversal tensile failure occurred in all cases.