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New products based on a structure that represents a combination of known elements in a higher quality set, as well as products that refer to new shapes, new curves, new surfaces can be obtained logically - analytically - deductively or by methods specific to the optimal calculation. The present paper focuses on the method of analyzing tridimensional morphology, some possible solutions being evaluated on value criteria. Of course, these methods can be applied in the field of engineering with very good results. The focus of this study is to obtain new thin walled tubular structures - such as car crash members - which in the case of axial shock loads have a higher predictable behavior compared to those already used in various technical fields. Following the study, it can be said that depending on the amount of absorbed energy in the case of axial collisions and the absorption of kinetic energy developed at the time of impact, the optimal crashworthiness solution could be tubular structures with a circular support base and rectangular deformable area for impact.

The paper presents the results of a students&rsquo, survey carried out at &ldquo, Vasile Alecsandri&rdquo, University of Bacau, Romania, on the quality of educational process on online platforms in the context of the COVID-19 pandemic. The study was addressed to students from the Faculty of Engineering and the Faculty of Physical Education and Sports. The results of survey highlighted that most of students were satisfied with the measures taken by the university during the lockdown period and the way the teaching&mdash, learning-assessment process took place. However, some negative aspects were reported as: lack of an adequate infrastructure for some students, less effective teacher-student communication and interaction, impossibility of performing practical applications, lack of socialization, lack of learning motivation, less objective examination (e.g., possibility of cheating), possibility of physical and mental health degradation (e.g., too much time spent in front of screens, installation of a sedentary lifestyle). Consequently, for the new academic year, effective, and efficient measures must be implemented by the management of the university to remove, as much as possible, these negative issues and to improve the performance of online educational process.

Obtaining a new product, in the current stage, can no longer be achieved by waiting for it by chance, as it happened in the past, but by systematically, perseveringly, and scientifically looking for it. This paper is a case study on the application of a systematic methodology for generating solution concepts in the case of the PVC and AL joinery accessories industry. Considering that one of the requirements was that the new connector part should mount on several standardized profiles, by approaching the TIPS tools kit, a modular connector with superior strength characteristics (3%) and low complexity was obtained. Also, by rethinking the product, a reduction of 15% of the required material (PA type 6) was obtained, as well as a decrease by approximately 11% of the tools cost necessary for the manufacturing process. For the preliminary evaluation of the new product, finite element analysis was necessary and the SolidWorks Simulation 2019 software was used. The numerical data was compared with the experimental data provided by the beneficiary, the differences being within the limit of 3.5%. These data encourage the beneficiary to study in detail the new product from several points of view, considering the option of introduction into manufacturing.

This paper aims to determine the influence that water jet cutting parameters have on dimensional accuracy. The input parameters of this study were the workpiece material, that was made from 19 mm thick S235JR steel alloy plate, using a medium to high cutting pressure (2000, 2500, and 3000 bar), with a variable standoff distance (1, 2, and 3 mm) and a programmed quality of the cut from Q1 to Q5. A statistical interpretation of the results was conducted, and the experimental plan was obtained using the Response Surface Method. The samples were analysed for entrance and exit width of cut and kerf angle. A total number of 45 samples were measured, and the results were interpreted using an ANOVA analysis for statistical significance (p-value) and fit statistics (R2). The results have shown what values are optimum for the input parameters to obtain precision cutting quickly.

Abrasive water jet machining is an emerging non-conventional technology widely used in different industrial sectors due to its multiple economic and environmental benefits. The quality of processed surface depends on process parameters, abrasive material properties and processed material properties and is mainly expressed by surface roughness, shape and dimensional accuracy of cut, presence of striations and/or burr. The current paper aims to present the influence of water jet pressure and traverse speed on the quality of processed surfaces in the case of AL-EN AW 2017A - T4 aluminium alloy abrasive water jet cutting.

The paper presents the results of a students' survey carried out at "Vasile Alecsandri" University of Bacau, Romania, on the quality of educational process on online platforms in the context of the COVID-19 pandemic. The study was addressed to students from the Faculty of Engineering and the Faculty of Physical Education and Sports. The results of survey highlighted that most of students were satisfied with the measures taken by the university during the lockdown period and the way the teaching-learning-assessment process took place. However, some negative aspects were reported as: lack of an adequate infrastructure for some students, less effective teacher-student communication and interaction, impossibility of performing practical applications, lack of socialization, lack of learning motivation, less objective examination (e.g., possibility of cheating), possibility of physical and mental health degradation (e.g., too much time spent in front of screens, installation of a sedentary lifestyle). Consequently, for the new academic year, effective, and efficient measures must be implemented by the management of the university to remove, as much as possible, these negative issues and to improve the performance of online educational process.

Tubular thin-walled structures with different shapes of the cross-sections are widely used in various transportation systems as energy absorbing components to dissipate the kinetic energy during violent collisions and crashes. The aims of this paper are to obtain numerical data on the crashing of thin-walled structures made by multiple layers of steel sheets. A series of finite element calculations was carried out on four different models crashed axially in dynamic conditions by using LS_Dyna V971. The effect of the generated fold depth on the peak load and the mean crashing load of these types of structures were also examined.

Brazing is realized by joining the added material to the base material thus it is realised a solid joint between materials. The degree of dissolution of materials used in assembly is very important in realization of sustainable bimetallic joints that can be stamped successfully. The stamping creates areas where joints can give the size and material compression degrees because its variation. A better stamping of these bimetallic brazed plates can be obtained through the exactly determination of these material areas.

Nowadays, thin-walled structures and different materials destined to absorb kinetic energy initiated a great interest among the researchers from the auto, naval, military industries even from the protection equipment production industry. The main role of these structures is to absorb and dissipate the kinetic energy so the maximum level of deceleration to be limited. Thus, the structures collapse through progressive buckling. The aim is to control this progressive buckling as efficient as possible through the collapse mode or the construction technique. This collapsing mode is well described and characterised by the international literature [.The plastic strain history of the components constituting the thin-walled structure is very important because each bending, stretching process or tensioning brings with it self-a series of transformations which compete to influence the dynamic response of this kind of structures [2].In this study, all the above presented aspects were taken into consideration in the analysis of the impact and energy absorption behaviour regarding thin-walled structures by using explicit nonlinear finite element code LS_Dyna V971. The thin-walled structures involved in this research are made from tailor welded blanks (TWB) and were subject of axial impact crashing tests. There were used three types of cross-section shapes: rectangular, pentagonal and hexagonal. In order to have a fare comparison study, all the studied structures had a 250mm cross-section perimeter and a height of 250mm, also. Each structure is constituted from four, five or six sheet metal parts bonded together.

The current work deals with numerical simulation connected to forming of a rectangular shaped part made from tailored blanks, having the welding line positioned symmetrical with respect to the part geometry. The objective was to study the relation between the blank holder force applied during forming and the thinning of the parents materials. All the parameters are fixed except the blank holder force, its variation will cause variation of the material thinning. The presented work is trying to demonstrate the important role of the blank holder force on the material thinning during the deep drawing process. It must be mentioned that both materials from the welded structure are having the same thickness (1mm). The Dynaform 5.8.1 software is used to simulate the forming process. The part obtained after each simulation is analyzed and measured to quantify the on the material thinning. All the parameters are maintained fixed except the blank holder force. The obtained results for five different binder forces (5, 10, 30, 50, 70 kN) were compared to realise the behaviour of the tailor welded blanks during deep drawing process. In the final part of this paper conclusions regarding the influence of the blank holder force on the material thinning are presented.

The crash-boxes are thin-walled structural components with rectangular cross-section which are utilized in the construction of the resistance body structures in the auto industry. This components can be manufactured from various materials including homogenous steel sheet metals, tailor welded blanks (TWB) or even composite materials. The benefits of using TWB were shown in numerous studies before and they are not the main purpose here.This research focuses on the collapse behaviour of TWB thin-walled structures with rectangular cross-section subject of impact loadings. The main objective is to design a crash-box which allows the absorption and dissipation of great kinetic energy constituting better resistance structures for car bodies.After analysing the resulted data, a few aspects regarding the TWB crash-boxes were revealed and some conclusions could be suggested: the weld line generates a barrier like zone which delays in some manner the propagation of the progressive buckling levelling the mean crash load; no flange crash-boxes presented best results regarding the mean crash load even if the data were very close to the other crash-box types. Furthermore, the peak crash load was at maximum level comparing with the other crash-box types. This collapsing behaviour of the no flange crash-boxes could be assigned to the fact that the bonded sides of the structure work like double walls into the same cress-section and is not really affecting the asymmetric crash mode of the structure.

In previous studies, the cross-section geometries were either single cell (circular, prismatic) or multi-cell structures with identical cell properties. In the present research the collapse characterization of multi-cell structures consisting of three different types of cell formation defined by either two wide or two narrow angles separating the ladders is conducted. The shape characteristics of interest sum up the layout of the interior walls and their constraints over the outer structure walls. To study the control of cross-section geometry over the crashing mechanism, local or global progressive buckling response, energy absorption and crash load for the structures in discussion FEA simulations of the impact were performed.

The present paper investigates the crashing behavior and energy absorption characteristics of thin-walled (tubular) structures with different cross-sections made from tailor welded blanks (TWB) which were subject of axial quasistatic loadings. Resulted data were obtained by using explicit nonlinear finite element code LS_Dyna V971. Implementing the TWB into the auto industry was an efficient method to decrease the general weight of different structures. By far, these kind of bimetallic structures are largely utilized in auto and naval industries because it led to important decrease of scarp quantities and general manufacturing costs, improved material use and probably the most important, great fuel efficiency. After reviewing the literature it was concluded that proper combination between mechanical characteristics of sheet metals, different thicknesses and cross-section shapes into the same thin-walled structure is far too little researched and understood. The aims of this study are better understandings of the crashing behavior regarding thin-walled structure with various cross-sections made from TWB blanks subject to quasistatic loadings. The non-linear finite element platform LS_Dyna V971 was used for the numerical analysis of the crushing behavior regarding the thin-walled structures. Having two materials constituting the thin-walled structures, the crashing behavior changed during the quasistatic loading. Thus, the crashing inertia of the structure is somehow limited and controlled. It is noted that material ratio should not be randomly chosen due to the unexpected crashing mode which could aggravate the prediction and control of the crashing behavior of the thin-walled structure.

This paper investigates the crashing behaviour of thin-walled structures having various cross-sections subject of dynamic axial loading. The aim is to understand the collapse mode formation, energy absorption behaviour and progressive buckling phenomenon regarding TWB thin-walled structures. Three different cross-section shapes were used for this study as it follows: circular, hexagonal, rectangular. In the fabrication process of the structure itself, homogeneous materials are often used but an attractive solution for the automotive companies is materialized by the use of tailor welded blanks. In this paper, the impact crashing procedure was performed using a custom impact setup and the non-linear finite element platform LS-Dyna V4.0. After these analyses it can be concluded that a correlation between the number of folds and the mean load and the weld line could be made. The number of folds tends to increase as the mean load also increases. The weld line has an important role in the collapse mode formation and the values of the mean load.

In case of sheet metal forming the main dimensional errors are caused by the springback phenomena. The present work deals with numerical simulation related to draw bending and springback of U - shaped parts. The current paper is trying to prove out the important role of the blank holder force variation during the forming process. The Dynaform 5.8 software was used to simulate the forming process, in which the blank holder force varies in four steps between 0 and 50 kN. The factorial simulations test plan was made to cover completely the variation domain and 256 simulations were necessarily to be performed. The part obtained after each simulation is analyzed and measured to quantify the errors caused by springback. Parameters as: angle between flange and sidewall, angle between sidewall and part bottom, chamfer radius between part bottom and sidewall or chamfer radius between sidewall and flange are recorded in a data base. The initial simulations plan together with the generated data base is used as an input for the genetic algorithm optimization method. With the optimized process parameters a new simulation is made and the final shape of the part is compared with the ideal geometry. The shape of the part obtained with the optimized parameters is proving the capability of the proposed method.

The quality of weld line in a tailor welded blank (TWB) is an important factor that can affect the quality of the deep drawing process and resulted drawn parts. Hence, the behaviour of weld line during forming must be made with responsibility and by applying different physical testing methods in order to obtain useful and accurate information. For example, the mechanical properties of TWB and weld line, that give information concerning yield limit and ultimate strength, can be generally determined by applying the following techniques: parallel tensile testing or normal tensile testing. But, since the welding process can induce specific properties in the weld joint and heat – affected zone, the simple tensile test is not enough to obtain the needed information concerning such properties. The present paper investigates the behaviour and mechanical properties of the weld line in a tailor welded blank during and after its tensile testing by applying the following testing methods: parallel tensile test, micro-hardness testing, thermography, EDX and microscopy.

Cross flow filtration is the typical way that water is filtered in membrane technology; that means that feed solution passes tangencially over the membrane and rejected components are washed away of the membrane by the rejected stream. In such a way, that minimal solids building up and at constant low flow resistance are achieved. In this paper, a calulation method regarding to the value of cross-section active area for a polymeric spiral wound reverse osmosis (RO) membrane is presented, in order to obtain the value of the cross-flow velocity of the system. This velocity is needed to improve the knowledge fouling mechanisms and it is not easy to know without obtaining the cross section area. To determine cross-section area of a RO polymeric spiral wound membrane a series of calculations were performed to obtain the initial values of some parameters. The mathematical calculation was also achieved with the Roll Length program. Based on the results obtained, it was concluded that only 65.36% of the total cross-section of the membrane is useful to cross flow and it was possible to determine the active cross-section of filtration with a value of 1,915.4 mm2, for the membrane studied. This methodology allows the calculation for any RO spiral membrane.