Analysis of stress and deformation fields of shape complex beams

In this paper is investigated the analysis of stress and deformation fields of shape complex beams. The shape complex beams are made from load-bearing sheet (trapezoidal sheet) circumferentially connected with strips of sheet metal, these beams are a substitute for more complex and heavier beams. The numerical analysis with static load are performed for these beams. The effect of three different types of connections between load-bearing sheet and strips of sheet metal is investigated. The first type of connection is represented by the trapezoidal sheet perfectly welded to the strips of sheet metal, the second type of connection is represented by the trapezoidal sheet welded to the strips of sheet metal only on the base sides of the trapezoidal sheet. The third one is represented by point welds. The stress and deformation fields for all types of the connections are compared and the suitable variant is chosen

Analysis of stress and deformation fields of shape complex beams

In this paper is investigated the analysis of stress and deformation fields of shape complex beams. The shape complex beams are made from load-bearing sheet (trapezoidal sheet) circumferentially connected with strips of sheet metal, these beams are a substitute for more complex and heavier beams. The numerical analysis with static load are performed for these beams. The effect of three different types of connections between load-bearing sheet and strips of sheet metal is investigated. The first type of connection is represented by the trapezoidal sheet perfectly welded to the strips of sheet metal, the second type of connection is represented by the trapezoidal sheet welded to the strips of sheet metal only on the base sides of the trapezoidal sheet. The third one is represented by point welds. The stress and deformation fields for all types of the connections are compared and the suitable variant is chosen

The Assessment of the Residual Stresses Influence on Generation of the Infringement in Shape-Complex Supporting Members

The aim of the paper is to assess the effect of residual stresses on the damage of the slide bearer. To quantify the residual stresses, the drilling method using SINT MTS 3000 drilling machine was chosen. The tensometric rosette application areas were determined based on the analysis of the results obtained by numerical modeling using the finite element method. Experimental measurement was performed on one unused slide bearer and on the other one, which during its present operation had completed about 9.106cycles. At the end of the paper, the analysis of the measured residual stress values in chosen locations is presented

Estimation of Material Properties of Carbon Nanotubes Using Finite Element Method

The paper deals with estimation of material properties of single-walled carbon nanotubes (SWCNTs). The SWCNTs are simulated as frames, where carbon atoms are replaced by nodes and interatomic interactions are replaced by beams. The tension and torsion loading is applied on SWCNTs for determining the elastic modulus, Poisson’s ratio, shear modulus and membrane stiffness of SWCNTs. The simulations for obtaining elongations and torsion angles of SWCNTs are accomplished by the finite element method

Trajectory Tracking Controller of Air Bellow

Abstract The paper deals with describing of air bellow and designing of control system for its trajectory tracking. A lot of research works were done in the past concerning to pneumatic cylinders and their control systems based on servovalves. This paper investigates unconventional pneumatic actuator -air bellow, which is controlled by two two-way normally closed valves in consideration of expensive servovalves. In the paper air bellow is described as mass-damper-spring mechanical system of 2 nd order. The paper also introduces the control system for purposes of trajectory tracking of air bellow top platform. Derived algorithm was experimentally tested on measuring stand while control system consists of PLC B&R X20 in collaboration with input / output measuring card MF634 working through the software Matlab / Simulink. The results show that used methodology is suitable for certain applications, where it is not necessary to achieve high precise of positioning and also there is requirement to stiffness of mechanical system

Design and Implementation of a Low-Cost Torque Sensor for Manipulators

Humanoid and collaborative robots find their application in numerous sectors, such as automotive, electrical and mechanical engineering, not excluding the field of bioengineering. They replace repetitive and often monotonous human activity. As the trend nowadays is for continuous optimization of production processes, their advantage is easy relocation and operative application to new tasks, which allows the automation of practically all manual work. A common feature of manipulators is the control of the positioning of the actuators, primarily by adjusting the parameters of the drive units. Feedback is often implemented through various sensors that provide real-time information. However, most of the sensors in use do not provide information that would allow obtaining data on the history of the operating load in order to assess the further safe and reliable operation of the mechanical parts. This paper presents a low-cost torque sensor that was proposed by modifying the design of an existing part. The torque sensor was developed on the principle of strain gauge measurement. The results of strain–stress analysis obtained by numerical modelling were experimentally validated under static and dynamic loading. Practical application is mainly the development and long-term testing of prototypes of various types of manipulators and collaborative robots, where high accuracy and repeatability of positioning are essential

Experimental Investigation of the Fatigue Life of a Bridge Crane Girder Using S-N Method

Experimental measurement methods used in operational mode provide valuable information about the behavior of mechanical parts of equipment that cannot be determined in advance by analytical calculations or numerical modeling. The strain gauge method, which is often used to investigate the stresses in the load-bearing members of steel structures under operational conditions, was used. The advantage is the fast and accurate acquisition of stress values at critical locations selected based on analytical computations or numerical modeling. In the present paper, the residual operating life of two main girders of a bridge crane was assessed by an analytical-experimental approach. The input parameters for the assessment were obtained from the evaluated stress time records and using the Rainflow Counting method. Experimental measurements identified an almost 50% decrease in the residual life of one of the girders. It was caused by non-compliance with the technological procedures for the regular replacement of the rails, where the rail was welded to the top flange on one of the girders. Considering realistic operating conditions, predicting the effect of welded rail on fatigue damage accumulation, performed by other than experimental procedures, is almost impossible for such complex structures. This paper not only documents the importance of experimental measurements but also highlights the significance of selecting measurement locations with consideration of the current technical state of the structure

The Use of Optical Methods in the Analysis of the Areas with Stress Concentration

Anchoring parts of technical systems are often damaged due to the heavy forces acting on these systems during their operation. For that reason, various modifications are suggested and created on the anchoring screws, which should help to reduce the mechanical stress values in a place of the first load-bearing thread of a female screw. For the determination of stress fields on the surface of a plane model of a threaded joint, two non-contact optical methods were used – conventional transmission photoelasticimetry and modern digital image correlation

Experimental Investigation of the Fatigue Life of a Bridge Crane Girder Using S-N Method

Experimental measurement methods used in operational mode provide valuable information about the behavior of mechanical parts of equipment that cannot be determined in advance by analytical calculations or numerical modeling. The strain gauge method, which is often used to investigate the stresses in the load-bearing members of steel structures under operational conditions, was used. The advantage is the fast and accurate acquisition of stress values at critical locations selected based on analytical computations or numerical modeling. In the present paper, the residual operating life of two main girders of a bridge crane was assessed by an analytical-experimental approach. The input parameters for the assessment were obtained from the evaluated stress time records and using the Rainflow Counting method. Experimental measurements identified an almost 50% decrease in the residual life of one of the girders. It was caused by non-compliance with the technological procedures for the regular replacement of the rails, where the rail was welded to the top flange on one of the girders. Considering realistic operating conditions, predicting the effect of welded rail on fatigue damage accumulation, performed by other than experimental procedures, is almost impossible for such complex structures. This paper not only documents the importance of experimental measurements but also highlights the significance of selecting measurement locations with consideration of the current technical state of the structure

Application of Advanced Measuring Methods for Identification of Stresses and Deformations of Automotive Structures

In the automotive industry, 3D laser scanning is the most frequently used method to check the geometry of the shape and dimensions of a body in individual stages of production, where the scanned model is compared in a computer model. This procedure identifies excessive deformations around the roof antenna of an SUV. The manufacturer assumed that these deformations occurred during the antenna assembly process. An analysis of possible causes of deformation occurrence was performed based on the comparison of results obtained by numerical and experimental modelling. Experimental measurements using tensometry performed on a painted and unpainted roof structure showed the effect of paint reinforcement on deformations around the antenna. Based on the analysis of results obtained directly under operational load, it was found that the installation of the antenna was carried out on the already deformed roof plate and the installation process itself was not the primary cause of the identified excessive deformations. The presented results of deformation and stress analysis document deeper connections between the measured displacements of 3D scanning and the technological process of component production itself. The use of the achieved results should especially help designers, calculators, technologists as well as production quality controllers