Search

The article describes a method of creating a mesoscale finite element model of a fabric reinforced laminate that replicates the smallest repetitive fragment of its microstructure – RUC (Repetitive Unit Cell). The model takes into account the influence of the number and orientation of layers, the weave of the reinforcement fabric as well as manufacturing technology on the strength and stiffness of the laminate. The constants of the finite elements forming RUC (equivalent cross-sectional parameters, limit values of forces ensuring layer integrity) are determined experimentally by performing uncomplicated tests of specimens of a particular laminate. A special preprocessor was developed to generate the finite element model of the construction element from laminate, which automatically creates the so-called batch file defining the model. The usefulness of the preprocessor was checked by simulating a three-point bending test of a laminate door beam of a passenger car. The obtained calculation results were verified experimentally.

Layer composites reinforced with fabrics – laminates are construction materials in which mechanical properties can be shaped by designing their microstructure appropriately. However, the multi-phase microstructure of laminates makes it difficult to calculate the strength of the laminate constructions, especially when the reinforcement is a fabric. The article presents a special calculation model for determining the strength of an exemplary construction element made of laminate reinforced with a roving fabric with a plain weave made of carbon fibers. The computational model reflected in a simplified way the laminate microstructure, i.e. the number and orientation of the reinforcement fabric layers and its weave, and enabled a simulation of the behavior of the construction element under load up to fracture, which occurred as a result of breaking the reinforcement and interlayer crack – delamination. The simulation results were compared with the results of experimental stand tests. A method of modifying the computational model for laminates reinforced with non-plain weave was also suggested.

Adhesive bonding between steel and carbon-fiber-reinforced polymer (CFRP) composite leads to hybrid structures that combine the high strength and ductility of steel with the excellent specific strength and stiffness of CFRP composite. There is, however, a concern regarding possible galvanic corrosion when steel and carbon fibers are bonded together. One way to overcome this problem is placing glass fiber-reinforced polymer (GFRP) composite between the steel and CFRP composite, creating a more complex steel/GFRP/CFRP hybrid structure. Therefore, experimental and numerical studies on the mechanical behavior of the adhesive bonds between the steel sheet and the GFRP/CFRP hybrid composite were carried out. Among the different failure patterns, mode II was chosen for analysis because metal–polymer composite structures are usually subjected to bending, and debonding may occur due to in-plane shear stress. The tested steel/GFRP/CFRP hybrid structure was made of a hot-formed 22MnB5 boron steel sheet, intermediate single-ply bidirectional GFRP composite, and three-ply unidirectional CFRP composite. Additional mechanical tests were also carried out to determine various engineering constants of the components to simulate the debonding process. A finite element model of the steel/GFRP/CFRP hybrid structure with a typical cohesive interface was established and verified against the experimental data. The results showed that due to the use of various materials, the dominant failure modes in the hybrid structure under bending loading were a brittle fracture of the CFRP composite and debonding between the steel and the GFRP composite. However, the load-bearing capacity of the hybrid structure was five times greater than that of a non-reinforced steel sheet. In addition, its mass was only 28% greater than the non-reinforced steel sheet. The obtained results provided valuable conclusions and useful data to continue further research on the mechanical behavior of steel/GFRP/CFRP hybrid structures. [ABSTRACT FROM AUTHOR]

This paper presents a proposal for the use of energy indicators to evaluate the load modelling methods on the dynamics of a mobile crane. Three different variants of mathematical models of a load carried were examined and compared: as a lumped mass on one hook-sling, as a sphere on one hook-sling, and as a box on four hook-slings. The formalism of joint coordinates and homogeneous transformation matrices were applied to define the kinematics of the system. The equations of motion were derived using the Lagrange equations of the second kind. These equations were supplemented by the Lagrange multipliers and constraint equations formulated for the cut-joints and drives. The energy indicators were proposed to evaluate the behavior of the crane and the carried load. The authors proved that modeling a load in the form of a lumped mass is a great simplification in the analysis of crane dynamics. [ABSTRACT FROM AUTHOR]

Layer composites reinforced with fabrics – laminates are construction materials in which mechanical properties can be shaped by designing their microstructure appropriately. However, the multi-phase microstructure of laminates makes it difficult to calculate the strength of the laminate constructions, especially when the reinforcement is a fabric. The article presents a special calculation model for determining the strength of an exemplary construction element made of laminate reinforced with a roving fabric with a plain weave made of carbon fibers. The computational model reflected in a simplified way the laminate microstructure, i.e. the number and orientation of the reinforcement fabric layers and its weave, and enabled a simulation of the behavior of the construction element under load up to fracture, which occurred as a result of breaking the reinforcement and interlayer crack – delamination. The simulation results were compared with the results of experimental stand tests. A method of modifying the computational model for laminates reinforced with non-plain weave was also suggested. [ABSTRACT FROM AUTHOR]

The quality of web produced by a carding machine is largely influenced by the shape and height of the gaps between card clothings of workers and the doffer cooperating with the main cylinder as well as between the doffer clothing and doffing blade. The following paper describes the methodology of selection of a structural form and basic dimensions of the carding machine shafts and cylinders taking into account the gap shape in the zones of card clothing cooperation. For the study to be complete, optimisation of the blade and comb shaft cross-sections was also performed. The benefit from optimisation of the carding machine components is the improvement in the quality of the web - the final product of carding. [ABSTRACT FROM AUTHOR]

The following article shows the FEM model of a laminate composite reinforced with fabric made of roving of carbon fibres. The model considers the internal structure of the reinforcement. This model was used for a simulation of a crack propagation in the 16-layers of carbon fibre laminate. The analyses were conducted in reference to the first way of cracking. The results of the simulation were then compared with the results of the experiments. [ABSTRACT FROM AUTHOR]

The following paper presents the solution to the problem of searching the best shape – structural form of the bottoms and optimal dimensions of the main cylinder of the carding machine with consideration to the criterion of minimal deflection amplitude of its shell. The Finite Element Method has been applied for searching the optimal solution. As a result of the performed analyses, reduction of deflection amplitude at approximately 77% has been obtained. The determined optimal structural form and dimensions of the cylinder enable application of a new textile technology – microfibre carding as well as improvement in the quality of traditional carding technology of woolen and wool-like fibres performed on roller carding machine. The final stage of the work has been to determine the influence of manufacturing tolerances of the cylinder and metallic card wire on the amplitude of the main cylinder deflection. [ABSTRACT FROM PUBLISHER]

This paper presents a methodology for the analysis of mechanical doffing comb devices taking off the web in carding machines. The continuous model of the doffing comb shaft (a beam performing coupled bending--torsional vibrations) and the discrete model of the doffing device with the use of finite element method are presented. The results of the analysis using the calculation model are compared with the results of the experiment, affirming the correctness of the adopted assumptions. Criteria of the comb device evaluation are formulated. On the basis of the results of computer simulations, diagrams of comb devices' selection to rework a given range of fibers are described. [ABSTRACT FROM AUTHOR]

The paper presents the discrete calculation FEM model used in the analysis of the working cylinder shell deflection with regard to the real construction features. The influences of shape deviation, the thickness of the wall, flexibility and the clearance between internal reinforcements and the shell on the shell deflection have been examined. The calculating model has undergone experimental verification and satisfactory compatibility with the results of experimental measurements has been achieved. [ABSTRACT FROM AUTHOR]

Copyright of Fibres & Textiles in Eastern Europe is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Presents practical engineering calculations for working cylinders on carding machines. Function of working cylinders; Background on a continuous calculation model of the cylinder; Overview of the discrete calculation model of the cylinder.

This paper presents the concept of a doffing comb device in a roller card based on the action of the comb shaft within the resonance area. The analysis of the vibrations of the shaft and the method for calculating its construction data have been elaborated. The rigid finite element method has been used to analyze the vibration, and the op timization method used to calculate its construction data, while its frequency of motion has been assumed. Results of the calculations are shown in a numerical example. [ABSTRACT FROM PUBLISHER]