Papers by Keyword: Force

Abstract: Ergonomic assessment systems were created for possibility of prediction and risk detection at workplace. Ergonomic assessment system EAWS (European Assembly Work-Sheet) includes assessment of body postures, action forces, weight of carrying loads and frequently recurring upper limb loads assessment. Assessment of action forces (forces generated by upper limb defined by EAWS) is problematic and there is a lack of means for effective assessment. This paper deals with design of electronic device for assessment of action forces generated by upper limb defined by EAWS with using of thin film FSR (force sensing resistor). The paper deals with identification of upper limb areas, where the generated forces are important for assessment by EAWS, deployment of sensors in identified areas, calibration of FSR sensor with regard to simply program implementation in microcontroller, determination of action forces in every by EAWS defined action force application and construction of sensing and evaluating part of electronic device.

Abstract: Statics is set up on the basis of 4 axioms of statics. Although these axioms are distillate and summarizing of the accumulated humankind's experience in long-range production and life, introduction of these axioms to statics seems a bit abrupt, especially the critical axiom "resultant of two forces" far fetched. This article was an attempt to present the embodying description of the effect of force and force system, based on the nature of effect of force and the equivalent and equilibrium of force systems. On this basis, theorem of two forces resultant and the theorem of two forces balance were proved, and the theorem of force systems equivalent was brought up. A new framework of static equilibrium system was built up to try to make a more perfect and more reasonable description for static equilibrium.

Abstract: The new wave-energy dynamoelectric equipment has small volume and its transportation is very relaxed for application in the wide ocean area etc. So it has certain competitive power and enhanced researching value. After analyzing the structure of the equipment, it is found that the displacement difference between the floater and reducing-velocity structure validates feasibility and efficiency of the equipment. In this paper, the displacement difference is mainly researched. At first, forces on the upper and lower parts are analyzed respectively. Then investigating their movements, some structural parameters are determined. At the same time, the problem that the discontinuous acceleration change of the movement of the reducing-velocity structure causes the impulsion to the whole equipment is found. In order to solve the problem, the solution that a spring is added to the connecting string is adapted. The improved equipment is checked and finally it is found feasible.

Abstract: Vehicle rollover refers to a dangerous lateral movement of a vehicle in contact with the ground when it rotates around its longitudinal axis to a certain angle degree or greater angle during moving. There are many factors that could cause the vehicle's rollover, including automotive structures, road conditions and the driver's condition. vehicle rollover can be divided into two categories, one category is tripped rollover (trPPiedorllover), the other is a rollover (maneuve curve caused by motion: niduecdorllove) The former refers to the generation of lateral slip when the vehicle is moving, and the obstacle on the road surface collides sideways with it its "tripped" The latter refers to the rollover caused by the vertical reaction force inside the wheels of the vehicle reaching to zero because sideways acceleration of the has exceeded a certain limit when the vehicle moves on the road (including a lateral ramp). In this paper, only the rollover caused by curvilinear motion will be studied.

Abstract: This paper continues some ideas accepted in scientific literature or enunciates by us in previous papers. As title indicates, we treated the case of 0/3/3 structural group with revolute joints, and application of this group in mechanisms. Three different proposals were done and discussed for the forces transmission indices. Finally an application was shown for a mechanism used in a leather ready-made industry.

Abstract: New approaches in lightweight design require the use of multi materials like metalpolymermetal composites. Composite materials, especially so-called sandwich panels, offer the possibility to combine properties of different materials synergistically. Shear cutting is one of the commonly used manufacturing processes. However, conventional shear cutting of sandwich panels leads to characteristic types of failure, such as high bending of the facings, delamination effects, burr formation and an undefined cracking of the core material. In the present research, the cutting force requirement and the failure progress for lubricant free shear cutting of metal-polymer-metal composites is studied. Two thermoplastic polymers, an aluminum sheet and an unalloyed steel sheet are combined in order to create different composite materials. Furthermore, the composite materials are cut stepwise to examine the different stages of a cutting process in detail.

Abstract: An Approach that measuring static radial and axial runouts around rotational centre of spindle for cylindrical mills on milling machine was presented, its possible errors coming from imprecise location of gauge were theoretically analyzed. Milling force measuring experiments with variable feeds and cutting depths in low spindle speed was done to estimate the static runouts, these estimated values then were used to test the precision of measured values with this approach. Both results of theoretical analysis and experimental test showed that the relative errors of this measuring approach were small. This approach is to measure the runouts of installed mills, and its measured value is rather precise, its operation is simple, and it needs no special gauge. This approach can be used in study on force of cylindrical mills.

Abstract: Acoustic emission method is often used to detect a failure at a very early stage of damage long before a structure completely fails. The paper presents experiment focused on analysing acoustic emission signals captured during commonly used static modulus elasticity test of specimens of concrete. Quantitative acoustic emission techniques were used to measure micro fracture properties. For three different concrete mixtures typical acoustic emission patterns were identified in the acoustic emission records to further describe the under-the-stress behaviour and failure development. Although we are able to predict failure loads and damage patterns to some extent, we still do not have a good understanding of the relationships between micro structural phenomena and the corresponding effects on macroscopic behaviour. It logically follows that if we have a better understanding of the relationships between micro structural events and macroscopic behaviour, we will be in a better position to formulate predictive models for large-scale structural performance and reliability. An understanding of microstructureperformance relationships is the key to true understanding of material behaviours. Since we know that material microstructure influences its properties, and that cement-based materials of different microstructure have different failure properties and then the variations in micro fracture phenomena must be manifested in the acoustic emission response of the different specimens.

Abstract: Grinding is one of the most difficult processes in machining operations. Normally, the flood coolant method was used as a cooling agent in the grinding process. The most common defects using flood coolant are higher grinding friction, higher heat generation, and thermal damage. Therefore, the minimum quality lubricant (MQL) was introduced to minimize the defects. The main objective of this project is to compare the performance of MQL and flood coolant techniques in terms of grinding temperature, grinding force and specific energy. Three levels of cutting speeds, three levels of feed rate and depth of cut are adopted in the evaluation. The experiments were conducted on a thin plate of mild steel AISI 1020. The result shows that the MQL technique was effectively supplied to the grinding contact zone. This research revealed that the MQL technique exhibited an advantages on the surface temperature compared to the flood coolant.

Abstract: In this paper, according to the method of keeping wavelength the same, while the amplitude and unfolding length approximately equivalent, trapezoidal wave is transformed into sine wave. On this base,the bearing capacity under axial compression, pure bending, shear of corrugated web member of two kinds of wave forms converted respectively are compared. Results show that under the same loading condition, stress distribution of the two kinds of corrugated web member section is basically the same. By using different waveform conversion method presented in this paper, the equivalent conversion between different corrugated web member can be easily realized.