<abstract>
<title style='display:none'>Abstract</title>
Bridges are always subjected to different types of loads, which can be divided into three big categories: vertical loads, transversal loads, and longitudinal loads. The primary function of a bridge is to have good performance under heavy loads represented by cars, trucks, trains and sometimes tanks. The aim of this paper is to provide an overview regarding types of loads that can appear on bridges with the main focus on loads generated by vehicles. This description will contribute to our future studies. We aim to develop future research and perform different types of stress calculations on the Octav Băncilă passage from Iași (Romania). Finite element analysis will be conducted on vehicle loads generated by trucks, which act on the bridge structure, simulating different loading scenarios. Based on the values of the stress calculations, we will highlight dangerous sections and take measures to enhance the reliability degree of the analyzed bridge.
</abstract>

Loads on Bridges - Overview

<abstract>
<title style='display:none'>Abstract</title>
Composites occupy an important place in high-end industries due to their superior characteristics compared to traditional materials or individual constituent materials.
The work focuses on the FEA analysis of composite materials with CFRP carbon fibers with polymer matrix subjected to tensile and shear loads, an important subject of study in the field of engineering. The analysis using the finite element method is a real help by simulating the materials in different conditions. Due to their advanced properties, composite materials can be tested and optimized before being used in production. This can reduce the need to make prototypes and testing multiple times. The aim is to increase productivity and eliminate excess waste, an important process that is the basis of all industries today.
Modified butterfly-type specimens were used in these research studies to be tested on the Arcan device. The simulation conditions were similar to a tensile and shear test conducted in the laboratory, considering a material without cracks or other impurities in its structure and utilizing mechanical properties provided by software Ansys for unidirectional carbon fiber and epoxy-reinforced matrix.
</abstract>

FEA of Carbon Fiber Reinforced Polymer Subjected to Tensile and Shear

<abstract>
<title style='display:none'>Abstract</title>
This paper presents a concise review of cooling techniques for the solar PV systems.
The photovoltaic effect was firstly experimentally demonstrated by the French physicist Edmond Becquel in 1839. The first useful solar cell (6% energy efficiency) was performed by the Bell Laboratories (1950). They realized that the semiconducting materials such silicon were more efficient than selenium.
The following conditions have a significant impact on solar panel’s efficiency, in real-world use: irradiance (W/m2), shading, orientation and temperature. The ambient temperature, wind speed, time of day and the amount of solar irradiance (W/m2) make real variation in cells temperature that often rises above 25ºC. The optimum internal cell temperature is typically 25-30ºC above the ambient air temperature and solar cell performance decreases with increasing temperature with 8-15% in total power output. That’s why engineers design cooling systems to improve the efficiency of solar panels that operate in non-optimal conditions.
</abstract>

Design and Development of Cooling Systems for PV Cells Performance Improvement

<abstract>
<title style='display:none'>Abstract</title>
In the paper are present a practical procedure involving the determination of crack propagation rate using da/dN software. The procedure of the tests, the presentation of the da/dN software and its operation, the hypothesis and the conditions of the experiment and the results obtained from the experiment were presented. The determination of the yield strength and elastic characteristics was used, in which the steps for carrying out an experiment in the laboratory were explained. This was carried out by choosing the materials, presenting the apparatus and the specimen to be analyzed, and the results obtained from the experiment. It should be mentioned that da/dN software was used to obtain the results. The paper illustrates the dependencies between crack growth and the number of loading cycles, demonstrated by two experimental methods. The theoretical part underlying the two experimental methods, the calculation relations used, the importance and role of the da/dN software in their realization are discussed, and the conclusions of the study are presented at the end.
</abstract>

Determination of Fatigue Crack Propagation Rate by Two Methods

<abstract>
<title style='display:none'>Abstract</title>
Motivation in the workplace is a topic of interest for organizational managers. This article provides readers with systematic ideas from the literature on the importance of consistently motivating human resources.
Within the article, motivational theories in organizations will be analyzed through a review of the specialized literature. This analysis shows that the level of satisfaction experienced by an employee reflects in their desire to work. In other words, a strongly motivated employee will achieve better performance at work.
The article highlights motivational theories developed by specialists that help organizations to understand and determine the needs of human resources.
This way, employees can be properly stimulated according to their own needs and expectations, recording maximum performance, while also helping to achieve organizational objectives. In addition, the article brings to the attention of readers news regarding the necessity of organizational potential of companies, as well as a workforce in accordance with the requirements of daily activities.
</abstract>

Perspective on the Motivational Theories in Organizations

<abstract>
<title style='display:none'>Abstract</title>
The advantages of Additive Manufacturing (AM) over conventional manufacturing processes are incontestable: complex geometries of obtained parts, wide variety of materials (polymers, composites, low melting metal alloys) used, simple and cost-effective process. Material Extrusion (ME) (piston, filament or screw) is the most widespread AM technology. In this paper, a comparative analysis of different materials used in high reinforcement 3D printing is made. Thus, ceramic and metallic composites, composites with titanium particles, AISI M2 high speed steel powder and Nickel 625 alloy are presented. The conclusion of each study is that increasing powder concentration (up to 65%, by volume) increases parts density (up to 90%), improves sintering process, but narrows process parameters. A balance between raw material properties and processing parameters must be sought to obtain custom parts with optimal properties.
</abstract>

Obtaining Metal Parts by Additive Manufacturing, as an Alternative to Traditional Manufacturing Methods – A Review

<abstract>
<title style='display:none'>Abstract</title>
In order to increase the safety of vehicles, the braking systems have two different braking sequences: the service brake and the secondary brake. The secondary brake is used when a component of the braking system fails to work adequately and it uses only two main components of the brake system, the calipers and the master cylinder. This paper presents a method of investigation, based on Matlab Simulink, to be used to verify the efficiency of the secondary brake by studying the dynamics behaviour, brake bias, stability and control during braking. The outputs are discussed by having in view, the ECE R13 regulations, for a vehicle with the initial speed at v = 60 km/h, mass m = 2300 kg, rolling radius r = 0.32 m, master cylinder mc = 22.2 mm, pedal ratio 4.3 and static friction coefficient 0.9. The results confirm that the variation of yaw rate and slip ratio have a minor influence on the stability and control.
</abstract>

Investigation on the Performance of a Secondary Brake

<abstract>
<title style='display:none'>Abstract</title>
The directional cosines matrix makes the link between the reference frame and the mobile frame in the kinematics of the rigid. This paper determines the matrix in the event that three of its elements are knowns, in a particular case.
</abstract>

eugen-neculai.corduneanu@academic.tuiasi.ro

The Determination of the Elements of the Base Change Matrix in the Kinematics of Rigid Body in a Particular Case

<abstract>
<title style='display:none'>Abstract</title>
The 3D printing is a technology of manufacturing that is now well known. Usually the part is obtain using layer-by-layer deposition and the main inconvenience of this process is that the deposition of material takes place in the plane (2D space) and then it is moved to the next plane by applying a constant increment on the third axis. The accuracy of the product is given by the increment value. The properties of the product, such as strength, also is given by the bond that is made between the layer and the density of the layers. Nowadays, it is proposed a new type of 3D printing using robotic arms. This approach give the possibility to work in 3D space and obtain a 3D defined deposition. It is believed that the properties of the part will be improved together with the mechanical properties of the part. In this article will be presented a comparative study that will indicate the positive and negative aspects of both conventional 3D printing and robotic printing.
</abstract>

Comparative Study Between Conventional and Robotic Methods in 3D Printing

<abstract>
<title style='display:none'>Abstract</title>
The article investigates the applications of Axiomatic Design to the Project Management of new product development as it currently stands based on publicly available materials. Project Management is a collection of processes tailored to fit an application. The research focused on processes associated to Project Management, and it was less focused on product design. The results of the investigation indicate that the application of Axiomatic Design to Project Management would be useful and would lead to improvements of projects’ success and business’s Return-on-Investment. The researcher concludes that product requirements could be used to model a uniform approach to most processes used in Project Management but, depending on the project complexities, a smaller scope approach is more appropriate depending on company’s internal organization of work. It will be beneficial to either project management practitioner or any business manager to have a framework easy to utilize in designing processes as needed for the successful completion of any project.
</abstract>

Applications of Axiomatic Design in the Project Management of New Product Development – A Literature Research

<abstract>
<title style='display:none'>Abstract</title>
The aim of this paper is to detail the combustion factor used to calculate the design value of the fire load density in accordance with the European design code. The procedure only states the factor value for the mainly cellulosic materials, like wood, paper, cardboard, naturals fibres (cotton, linen) etc., but it gives no information about other types of fuels, like plastics, flammable liquids, rubber, etc.
Considering the vast types of fuels, for a correct appreciation of the input data used by different fire models, it is necessary to better understand the importance of the combustion coefficient and its appropriate value selection.
The combustion factor directly affects the value of the design fire load density which, in turn, affects the Heat Release Rate. Both parameters are used by different type of natural fire models (like parametric curve, zone models, CFD models) to simulate the fire development and to predict the temperature in the analysed space.
</abstract>

A Short Description Regarding Combustion Factor from Eurocode 1-1-2

<abstract>
<title style='display:none'>Abstract</title>
In recent times, people pay more attention to global warming because they realise its impact on the environment and human life. The main factor that influences it are the emissions produced by the transportation industry. Automobiles are one of the biggest source CO2 emissions. Because the engine efficiency is low, most of the energy produced is lost as heat. If the lost heat is recovered and transformed to electrical energy it could power some of the automobile systems, thus reducing the fuel consumption and CO2 emissions. Among the researched power generation technologies, one of the most advantageous in this situation is the thermoelectric generator (TEG). TEGs take advantage of Seebeck effect to convert low temperature heat into electricity using materials similar to thermocouples. The purpose of this paper is to provide a comprehensive overview of the TEG, including its operational principle, the experiments conducted to test it, the materials used in its construction, and the methods employed to improve its performance.
</abstract>

Energy Recovery from Ice Waste Heat Using Thermoelectric Generators

<abstract>
<title style='display:none'>Abstract</title>
This paper proposes a simple approach on the synthesis of the 2D profiles for the rotors of cycloidal reducers. A 2D rotor (or cycloidal disc) profile (as a complex closed curve) can be defined (as an alternative to the strictly mathematical definition) as the internal bordered envelope of the family of 2D profiles of the stator (or ring gear) obtained with the stator movable (for at least a completely rotation) around the fixed rotor (or planetary gear) by respecting the gearing conditions inside a cycloidal reducer. The more 2D profiles of the stator are used the more accurate definition of 2D rotor profile is obtained. The finding of <italic>x</italic>, and <italic>y</italic>-coordinates of the points involved in the description of this 2D rotor profile is by far the most complicated problem to solve in the manufacturing of this type of reducer, the behavior and performances of the cycloidal reducer drastically depends by the accuracy of this profile. The results of this study can be easy applied in practice.
</abstract>

A Study on the Synthesis of 2D Profiles for Cycloidal Discs Used in Cycloidal Reducers

<abstract>
<title style='display:none'>Abstract</title>
This paper intends to introduce a new approach in cycloidal reducers design. The usual design uses rotary pins as teeth on the ring gear (or stator as well) and an appropriate conjugate profile on the cycloidal disc (or rotor as well). This study proposes a new approach: to use rotary cylindrical pins as teeth on the rotor and an appropriate conjugate profile on the ring gear (or cycloidal ring) according with the rules of gearing. The main achievements of this paper focus on the synthesis of 2D internal profile of the cycloidal ring in transverse section. Some theoretical achievements and computer aided simulation results are briefly presented in this paper. This 2D profile is useful mainly for cycloidal reducer computer aided simulation and optimization but also for manufacturing purposes (by contour milling on CNC machines).
</abstract>

A Study of 2D Profile for a Cycloidal Ring Used in a Cycloidal Reducer

<abstract>
<title style='display:none'>Abstract</title>
Actually, the Fused Deposition Modelling is one of the most popular Additive Manufacturing technology among ordinary users because of the low-cost equipment and the great variety of materials available on the market. Even many users mostly use it, not all of them are adopting the advanced parameterisation of the processes, preferring default set-up with a small interference over the basic parameters such as layer height, number of perimeters, and infill. Regarding the nozzle diameter, several advantages and disadvantages are implied by the relation of printing time-surface finish. Usage of large-diameter nozzles present advantages such as reduced manufacturing time, low risk of clogged nozzle, and more. Those cause worse resolution for small features and support structures to be more challenging to remove. By adjusting the nozzle parameters such as extrusion width and extrusion temperature, it was possible to obtain similar effects with a regular nozzle. This research’s main goal was to investigate if there is imperative the usage of larger-diameter nozzles for speeding up the manufacturing process, or the same effect can be achieved by using nozzles with a smaller diameter. In the end, we managed to reduce the manufacturing time to half compared to the initial time.
</abstract>

Influence of Nozzle Parameters in 3D Printing Under the Manufacturing Time

<abstract>
<title style='display:none'>Abstract</title>
The bond-graph method is used for finding the equations which describe the systems dynamics, by analysing the way of power transmission from the source to the working elements. When the energy storage elements I and C are in integral causality, the number of state equations equals the number of these elements. If there are also energy storage elements in derivative causality, the system contains a number of differential equations equal to the number of energy storage elements in integral causality and a number of algebraic equations equal to the number of energy storage elements in derivative causality. The work presents a new method for finding the system of differential equations for mechanical systems with one degree of freedom, starting from the original system which contains both algebraic and differential equations.
</abstract>

A Method to Find the Differential Equations from the Bond Graph Containing Inertial Elements in Derivative Causality

<abstract>
<title style='display:none'>Abstract</title>
The process of energy conversion of incidental solar radiation to useful electric energy in photovoltaic (PV) panels is affected by several external factors, of which panel operational temperature is of utmost importance. The present study attempts to clarify the theoretical components of thermal behaviour of PV panels, by taking into account the detailed structure of thermal resistances of panel layers. The numerical model, developed from the theoretical analysis, shows a good agreement with experimental data provided by manufacturer for the photovoltaic panel Suntech STP280 - 24/Vd.
</abstract>

Theoretical Model for Photovoltaic Panel Thermal Analysis

<abstract>
<title style='display:none'>Abstract</title>
There are situations where parts manufactured by 3D printing processes must have a high abrasion resistance. To conduct experimental research on this subject, relatively simple test equipment for abrasive wear of pin-on-disk type was designed and materialized. The test pieces from the research material were pressed with known forces on the surface of a rotating abrasive paper disk. The test pieces were made of polyethylene terephthalate PET and polyethylene terephthalate carbon fiber reinforced PET CF15. As output parameters, the speed of decreasing the mass and the length of the test piece were used, respectively, for predetermined test durations. An experimental Taguchi L8 program was used, with 7 independent variables at two levels of variation. The experimental results were mathematically processed determined empirical mathematical models of the power function type. It was found that the strongest influence on the values of the output parameters was exerted by the average travel speed and by the granulation of the particles incorporated in the abrasive paper disk.
</abstract>

Abrasion Resistance of Plastic Parts Manufactured By 3D Printing

Author Guidelines

Open Access License

Publication Ethics and Publication Malpractice Statement

Bulletin of the Polytechnic Institute of Iași. Machine constructions Section

Buletinul Institutului Politehnic din Iași. Secția Construcții de Mașini

 Machine Construction section, as part of the Bulletin of the Polytechnic Institute of Iasi founded in 1946, appears as an autonomous publication since 1950. Currently, it is...

 Machine Construction section, as part of the Bulletin of the Polytechnic Institute of Iasi founded in 1946, appears as an autonomous...

Bulletin of the Polytechnic Institute of Iași. Machine constructions Section

Buletinul Institutului Politehnic din Iași. Secția Construcții de Mașini

Tutti i volumi ed i numeri in questa rivista