Use Of Bolts Research Articles

Joining of hybrid busbars for E-Mobility: An economic and environmental study

This paper presents a model to evaluate and analyze the costs of joining hybrid (copper-aluminum) busbars when different production processes are deployed. The process-based cost model (PBCM) is built upon the subdivision of the production cycle in three different stages related with the fabrication or purchase of auxiliary joining elements, preparation of the individual copper and aluminum conductors, and final joining of the hybrid busbars. The total cost per hybrid busbar is obtained by converting the major physical, human, and financial resources associated with the production cycle into itemized costs that make use of the expenses in materials, labor working hours, number and usage time of machines and tools, among other production costs. Application of the PBCM is illustrated with three different joining processes and enriched with a life cycle assessment (LCA) focused on the environmental performance of hybrid busbars throughout its fabrication, service use and end of life. The combined economic and environmental sustainability analysis of joining hybrid busbars allows concluding that despite conventional fastening being the cheaper process it has the highest environmental impact due to the use of bolts, nuts and washers made from galvanized medium carbon steel. Injection lap riveting arises to be the most well-balanced process in terms of production cost and environmental impact.

Mechanical Fracture of Aluminium Alloy (AA 2024-T4), Used in the Manufacture of a Bioproducts Plant

Aluminium alloy (AA2024-T4) is a material commonly used in the aerospace industry, where it forms part of the fuselage of aircraft and spacecraft thanks to its good machinability and strength/weight ratio. These characteristics allowed it to be applied in the construction of the structure of a pilot plant to produce biological extracts and nano-encapsulated bioproducts for the phytosanitary control of diseases associated with microorganisms in crops of Theobroma cacao L. (Cacao). The mechanical design of the bolted support joints for this structure implies knowing the performance under fatigue conditions of the AA2024-T4 material since the use of bolts entails the placement of circular stress concentrators in the AA2024-T4 sheet. The geometric correction constant (Y) is a dimensionless numerical scalar used to correct the stress intensity factor (SIF) at the crack tip during propagation. This factor allows the stress concentration to be modified as a function of the specimen dimensions. In this work, four compact tension specimens were modeled in AA2024-T4, and each one was modified by introducing a second circular stress concentrator varying its size between 15 mm, 20 mm, 25 mm, and 30 mm, respectively. Applying a cyclic load of 1000N, a load ratio R=-1 and a computational model with tetrahedral elements, it was determined that the highest SIF corresponds to the specimen with a 30 mm concentrator with a value close to 460 MPa.mm0.5. Where the crack propagation had a maximum length of 53 mm. Using these simulation data, it was possible to process each one and obtain a mathematical model that calculates the geometric correction constant (Y). The calculated data using the new model was shown to have a direct relationship with the behavior obtained from the simulation.

Experimental Investigation of the Failure Scenario of Various Connection Types between Thin-Walled Beam and Sandwich Panel.

The paper presents failure scenarios for various types of connections between a thin-walled beam and a sandwich panel. In addition to standard connections used in civil engineering applications, that is, self-drilling fasteners for sandwich panels, the study examined the use of bolts, blind rivets, and double-sided acrylic tape applied linearly and pointwise. The connections were subjected to the horizontal load applied with constant eccentricity with respect to the plane of the connection surface. This load arrangement simulates the behaviour of a free flange of the thin-walled beam in bending while lateral-torsional buckling occurs. In this way, the research covers the determination of the lateral stiffness of the thin-walled beam-free flange, while the other flange is connected to the sandwich panel using various connection systems.

Discontinuity defects of the bolt head bearing surface

One of very common defects of bolt products are failures resulting from the plastic forming processes of materials. Surface discontinuity defects can take the form of folds, forging laps and cracks. These defects are known phenomenon associated with the production of bolt products, and they are described in the standard DIN EN 26157–3. The reasons for their formation may be different and the knowledge about improving the quality of bolt products is very important. Prevention of these defects is one of the key issues related to an improvement of product quality and implementation of a new bolt technology.The work presents and analyzes mechanisms of generating forging laps and cracks formed in a four- and five-stage cold forming processes of bolts. Three cases of defect generating were selected and analyzed using numerical simulations by the QForm3D software. The FEM results were compared with results of an experiment of bolt forging on a forging machine.In the first case, the influence of the volume of the material determined on the forging of the bolt head was examined. A variant with a constant volume and a variant with a volume that changed with successive stages were prepared. In the second case, dies with different geometry were used (constant or graded corner radii dies shaping the transition of the pin into the bearing surface of the bolt). In the third case, the shaping of the bearing surface of the bolt in one or two steps of forging was considered.Potential errors in the design of the process of shaping the bearing surface and threats in further use of bolts were indicated. Forging laps and cracks based on the microstructure of the material flow lines, photos and FEM simulations were presented.

Distribution of the friction coefficient in the tension connections by the HV set using the combined method

AbstractThe use of bolts in steel structures nowadays is one of the cheapest, fastest and easiest solutions for joining elements. HV high‐strength bolts used in tension connections are a special type of fasteners covered by supervision beginning with the selection of the material from which they will be made through the production process and quality confirmation, ending with clearly defined assembly requirements.The tests were focused on two assortments of M16 and M24 bolt assemblies made according to EN 14399. A test of the suitability of the connection was performed, expanding it with tests of the coefficient of friction on the bolt thread and between the nut head and washer according to EN ISO 16047. The dynamic joint load tests showed that the distribution of the coefficient of friction on the thread and between the nut and the washer affects the degree of tension through the preloading force.Tensile tests were carried out on the both aforementioned assortments. The determined yield point of the bolt was analyzed, which was referred to the stress causing plastic deformation in the test of connection suitability. Bolts in two systems of forces were compared with each other (simple ‐ stretching and complex ‐ stretching and torsion) and the difference between them was shown. Based on the correlation of results from both tests, the importance of the K‐factor on the mechanical properties of the HV set was emphasized. The dependence of the K‐factor on the coefficients of friction in a bolted joint has been demonstrated.HV high‐strength bolt sets consider assembly procedures using a combined method according EN 1090‐2. Cases of exceeding the yield point of the bolt during assembly and permanent deformation of the fastener have been shown. The scope of assembly was determined in the elastic range and the transition to the range of plastic deformations. Again, reference was made to the coefficient of friction and its effect on the difference in the obtained preloading force leading to risky assembly in the plastic range.

Analisa Posisi Peletakkan Baut terhadap Gaya Geser pada Sambungan Plat Baja

Research on analysis the effect of positioning the use of bolts on the connection process between the two steel plates against the other steel plates to determine the magnitude of the bolt torque moment and the magnitude of the force. The connection of the steel plate components where the joints are used are able to with stand shear forces, pressure and torsion. The research objective was to determine the effective placement of the bolt position and the distance of the load on the vertical and horizontal bolt position to the magnitude of the torque due to compression and the fracture model. Data collection was carried out in several tests of changes in the placement of the bolt joints, including the position of the bolts with three angles, in the vertical and horizontal position of the bolts. The findings of the placement of the three-angle bolt position at 2-4-11 the shear force experienced a shift / fracture of the bolt greater than the shear force that occurred in the horizontal and vertical bolts position, with a pressure of 92.66 bar (torsion moment 108,342 kg-mm). Testing the position of the three-angle bolt at 2-6-10 where the vertical bolt was broken with a pressure of 65.33 bar ( torque moment 76.401 kg-mm). The three-angle bolt placement test at 6-7-8 where the horizontal bolt was fractured at a pressure of 55.33 bar (torque moment 64,701 kg- mm). Comparison of the placement of the bolts in the position of three angles of the shear force between the vertical and horizontal positions, the shear forces experience the greatest shift / fracture of the bolts in the vertical position. The loading distance affects the amount of shear force that occurs on the bolt. the farther the loading distance, the greater the shear force that occurs.

Study on Support Technology of Deep Mine Roadway in Xingdong Coal Mine

Because of the large depth of the mine, the original use of bolt, mesh and spray composite support, the roadway shrinkage deformation is more serious, which not only affects the use but also endangers the safety of production. According to the deformation of surrounding rock and the characteristics of engineering technology, the following three different supporting technologies are adopted: the combined reinforcement technology of bolting and shotcreting grouting, the support technology of anchor cable on the floor, and the support technology of fully enclosed U-shaped steel ring support. The research results are applied to the field engineering practice. The monitoring results show that the fully closed U-shaped steel ring support technology has the best supporting effect, the roadway deformation meets the production requirements, the roadway renovation time is longer, and it can meet the requirements of the surrounding rock of the roadway with a depth of one kilometer.

Seismic performance assessment of a precast concrete-encased CFST composite wall with twin steel tube connections

A new type of Precast Concrete-encased high-strength Concrete-filled Steel tube (PCCS) composite shear wall with twin steel tube connections is proposed. Six two-storey PCCS wall specimens were prepared and tested under reversed quasi-static cyclic loading. The axial load ratio, the out-of-plane load eccentricity and the connection of the outer steel tubes are considered in this investigation of the assembly integrity and seismic performance of the PCCS walls. The experimental results show that the PCCS walls exhibit good assembly integrity and satisfactory seismic performance in terms of hysteresis behaviour, ductility, stiffness degradation and energy dissipation capacity. The use of bolts to radially fasten the inner and outer steel tubes can constrain the twin steel tubes. The out-of-plane load eccentricity significantly influences the cyclic behaviour. The specimens with large load eccentricity still have good deformation and ductility capabilities, which can be attributed to the ability of the embedded high-strength concrete-filled steel tube columns to improve the out-of-plane flexural capacity of a PCCS wall. Finally, the PCCS walls are compared with other typical precast concrete walls and cast-in-place concrete-encased concrete-filled steel tube composite walls in terms of ductility capacity, and a calculation model for shear bearing capacity is proposed and evaluated.

Strain-Stress State Analysis of Bolted Connection of Thin-Walled Steel Profiles in Tension and Compression

This work is performed within the study of framed structures with thin-walled profile elements. The results are provided for a numerical study of a three-bolt connection of a thin-walled galvanized plate with thickness of 1.5 mm and a metal-roll plate with thickness of 3 mm with the use of bolts with adjustable stress. Analytical models were created with the use of 3D elements in the Ansys software, taking into account strength properties of the materials.

Strength Comparison between Bolt and Cendani Bamboo (Bambusa multiplex) as A Shear Connector

Bamboo is a natural material that can replace wood, but the bamboo weakness is easily attacked by powder beetle and a bad connection system. a simple method of bamboo connection system often uses fibbers, ropes or rattan. However, this method cannot guarantee the unity of structural elements, over time the bonds will become saggy because the shrinkage that is affected by temperature changes. Another alternative can be done by using the bolt or the Cendani bamboo (Bambusa multiplex) as shear connector. The purpose of research is to know the ability of the bolt and the Cendani bamboo the shear connector in an element structures of bamboo. The research method is done by combining three pieces of bamboo with mortar filler using the bolt and Cendani bamboo as a shear connector, then apply the load to the ultimate limit. The result showed that use of bolt as the shear connector was stronger than Cendani bamboo. This is available with the results of the higher tensile strength of the bolt compared by the tensile strength of Cendani bamboo.

Strainburst characteristics under bolt support conditions: an experimental study

Strainburst, defined as a burst that occurs on the periphery of tunnels, is always associated with intact and hard brittle rocks and high geo-stress. In practical engineering, the prevention of strainburst by bolting does not achieve the desired effects. Deep insight into the strainburst process and mechanisms under bolt support conditions is necessary to ensure safe underground construction. In this study, strainburst characteristics under bolt support conditions were investigated using a true-triaxial rockburst testing system, which was equipped with an acoustic emission monitoring system. High-speed cameras were also used to capture the ejection failure process. Two indicators, namely kinetic energy and maximum decibel, were used to comprehensively evaluate the rockburst intensity. In addition, characteristic stresses, failure mode and cracking mechanisms under different bolt spacing conditions were investigated. The test results demonstrated that rockburst is greatly affected by the bolt arrangement. Rockburst changes from the way occurring in the form of a local failure in weak area to the way striking the bolt position and even the overall free face with the decrease in bolt spacing. The use of the bolt increases the rockburst intensity, but the intensity decreases as the bolt spacing decreases. Characteristic stresses including crack initiation stress, crack damage stress and peak strength increase monotonously with the use of bolt and the decreasing bolt spacing. During the strainburst, tensile failure dominates the cracking process regardless of bolt spacing; however, with the use of bolt and decrease in bolt spacing, tensile splitting near the free face become less obvious and the proportion of shear failure gradually increased.

02.06: Weldability of old mild steels within the rehabilitation of historical steel structures

ABSTRACTWelding process causes notch effects and residual stresses. Accordingly, the risk of brittle fracture grows. In comparison with currently used steels, old mild steels have a lower toughness. The weldability of mild steel is limited and only feasible under specific conditions. If for structural reasons welding is preferred instead of the use of bolts, the metallurgical characteristics of the steels have to be considered. These include the concentrations of impurities in the zones of segregation and the tendency to embrittlement by nitrogen‐induced ageing.In the corresponding paper, experimental and analytical studies of the weldability of old mild steels are presented. Extensive material analyses to determine the mechanical and the technological properties of the material will be an essential part of the investigations. Particularly, the increased impurities of phosphorus, sulfur, nitrogen and also oxygen in the segregation zones as well as the distinctive non‐metallic inclusions complicate to produce load‐bearing butt welds. Welding materials currently available are not designed for welding such materials. Nevertheless, in the context of a research project welding tests on old mild steels has been carried out using current welding electrodes. Supported by involved industrial partners, a stick electrode adapted to the characteristics of old steels will be developed.

Weldability of old mild steels in maintenance of historical steel structures

Welding process causes notch effects and residual stresses. Accordingly, the risk of brittle fracture grows. In comparison with currently used steels, old mild steels have a lower toughness. The weldability of mild steel is limited and only feasible under specific conditions. If for structural reasons welding is preferred instead of the use of bolts, the metallurgical characteristics of the steels have to be considered. These include the concentrations of impurities in the zones of segregation and the tendency to embrittlement by nitrogen-induced ageing.In the corresponding paper, experimental and analytical studies of the weldability of old mild steels are presented. Extensive material analyses to determine the mechanical and the technological properties of the material will be an essential part of the investigations. Particularly, the increased impurities of phosphorus, sulfur, nitrogen and also oxygen in the segregation zones as well as the distinctive non-metallic inclusions complicate to produce load-bearing butt welds. Welding materials currently available are not designed for welding such materials. Nevertheless, in the context of a research project welding tests on old mild steels has been carried out using current welding electrodes. Supported by involved industrial partners, a stick electrode adapted to the characteristics of old steels will be developed.

In situ experiments on supporting load effect of largespan deep tunnels in hard rock

A section of the Nanliang high speed railway tunnel on Shijiazhuang-Taiyuan high-speed passenger railway line in China was instrumented and studied for its mechanical properties and performances. The cross section for the tunnel was 300 m2 and is classified as the largest cross section for railway tunnels in China. Through in situ experimental studies, mechanistic properties of the tunnel were identified, including the surrounding rock pressure, convergences along tunnel perimeter and safety of primary support and lining structure. Based on the field measured data, the surrounding rock pressure demand for large-span deep tunnel in hard rock is recommended as double peak type in the vertical direction and fold line type was recommended for horizontal pressure. The results suggested that Promojiyfakonov’s theory was most close to the monitored value. Specific recommendations were also generated for the use of bolts in tunnel structures. Numerical simulation was used to evaluate the safety of the tunnel and it confirmed that the current design can satisfy the requirement of the current code.

On the Use of Shape Memory Alloy Studs to Recover Load Loss in Bolted Joints

Creep is an important factor that contributes to the clamp load loss and tightness failure of bolted joints with and without gaskets over time. Retightening of the joint can be expensive and time consuming; therefore, it is an undesirable solution. Currently, most efforts are put towards reducing load losses directly by tightening to yield, improving material creep properties, or making joint less rigid. An alternative solution of current interest is the use of bolts in shape memory alloys (SMAs). However, very few experimental studies are available, which demonstrate the feasibility of these alloys. The objective of this study is to explore the benefit of shape memory and superelasticity behavior of an SMA stud to recover load losses due to creep and thermal exposure of a gasket in a bolted-joint assembly. This paper explores several venues to investigate and model the thermomechanical behavior of a bolted joint with a nickel–titanium SMA stud. A stiffness-based analytical model which incorporates the Likhachev model of SMA is used as a representation of an experimental bolted-joint assembly. Based on this model, the rigidity of the experimental setup is optimized to make the best use of the SMA properties of the stud. This analytical model is compared with a finite element model, which also implements the Likhachev's material law. Finally, an experimental test bench with a relatively low stiffness representative of standard flanges is used, with and without gaskets to demonstrate the ability of the SMA stud to recover load losses due to gasket creep.

Strengthening of reinforced concrete beams with epoxy-bonded perforated steel plates

Although being one of the most popular strengthening techniques in reinforced concrete beams, the use of steel plates bonded to the soffit raises problems of ductility. This study aims at investigating the influence of the use of perforated steel plates instead of solid steel plates on the ductility of reinforced concrete beams. A total of nine reinforced concrete beams were tested. In addition to an unplated beam, eight beams with perforated steel plates of two different thicknesses (3 mm and 6 mm) were subjected to monotonic loading. Effect of bonding the plates to the beams with anchor bolts and with additional side plates bonded to the sides of the beam with and without anchors is also investigated. The use of bolts in addition to epoxy was found to greatly contribute to the ductility and energy absorption capacity of the beams, particularly in specimens with thick plates (6 mm) and the use side plates in addition to the bottom plate was found to be ineffective in increasing the ductility of a concrete beam unless the side plates are attached to the beam with anchors bolts. The thickness of the plate was found to have little effect on the bending rigidity of the beam.

Ground Support Strategies at the Turquoise Ridge Joint Venture, Nevada

Weak rock masses of high grade Carlin-trend gold mineralization are encountered in the Turquoise Ridge Joint Venture underground mine. The sediments consist of very weak and altered limestone, mudstone, and carbon-rich clays. The rock mass ratings are described as very poor to poor (Bieniawski in Proceedings of the symposium on exploration for rock engineering, Johannesburg, South Africa, pp. 97–106, 1976). The undercut and fill or boxes stoping mining methods are used because of the low dipping ore body geometry, complex geology, and weak rock mass. Design criteria are chosen to keep openings in weak rock as small as possible to prevent unraveling and to minimize supplementary support. Typical ground support for drifting includes the use of bolts, mesh, spiling, and shotcrete. Quality control of cemented rock fill (CRF) through sampling and aggregate sieve testing is necessary to insure high support strength. Specific support may include shotcrete arches with steel ring sets and CRF “arches” as a replacement of weak rock masses around long-term mine openings. Movement monitoring is utilized in problem areas and is needed to quantify and validate computer modeling.

Application of Rock Bolt Foundation in the Design of Metallurgical Industry Factory Building

Metallurgical industry factory building is usually high. Under the action of wind load and horizontal crane force, large moment will be induced at the column base. That is to say, the moment acting on the foundation is large. The embedded depth is relatively deep and the size of factory building foundation is relatively big. In the case of foundations based on the natural rock, if the routine design code adopted, the high capacity of the rock can not be fully utilized. The use of bolt at the bottom surface of the foundation integrates the foundation and the natural rock, hence reduces the foundation size and embedded depth to save the investment.

Load–deformation prediction for eccentrically loaded bolt groups by a kinematic hardening approach

The use of steel plates anchored on the sides of beams is effective in strengthening existing beams when they have deteriorated. The behaviour of the side plated beam is highly affected by the level of partial interaction between the components, which is provided by the use of bolts acting in groups. To determine the structural response of composite beams, the interaction through bolts or the load deformation response of bolt groups should be modelled. This study aims to develop a procedure to predict the non-linear load–deformation response of bolt groups subjected to combined in-plane moment and shear. The in-plane behaviour of bolts is first established by adopting the analogy from material plasticity. Then the incremental load–deformation responses of bolt groups are derived. Numerical examples are carried out and the results are verified by the available experimental results. The theory developed herein is able to model the load–deformation response of bolt groups and can potentially be applied to non-linear analyses of bolted side plated structures.

In Vitro Mechanical Comparison of Screwed, Bolted, and Novel Interlocking Nail Systems to Buttress Plate Fixation in Torsion and Mediolateral Bending

To compare standard interlocking nails (ILN) with a newly designed ILN featuring an angle-stable locking mechanism (ILNn). Six experimental groups. Bone models (n=48) treated with 6 and 8 mm nails locked with screws or bolts (ILN6s, ILN8s, ILN6b, ILN8b, respectively), ILNn, and a 3.5 mm broad-DCP (br-DCP); n=4/testing mode. Specimens were tested in torsion or 4-point bending. Construct compliance, deformation, and slack were statistically compared (P<.05). Regardless of testing mode, construct compliance was greater with smaller ILN. Screwed constructs were more compliant than bolted ones, with a significant difference between ILN6s and ILN6b in torsion. Plated constructs were significantly more compliant than the ILNn. Angular deformation was consistently greater with smaller ILN. Screwed ILN constructs sustained approximately 2 x the torsional deformation of the bolted ones (approximately 36 degrees [ILN6s] versus approximately 18 degrees [ILN6b]). Comparatively, ILNn constructs had significantly less torsional (approximately 8 degrees) and bending (approximately 4 degrees) deformation than other constructs. Whereas standard ILN constructs had slack in both modes, ILNn and br-DCP construct deformations consistently occurred without slack. Use of bolts rather than screws improved ILN mechanical behavior, but neither locking mechanism completely counteracted torsion and bending forces. Conversely, the ILNn angle-stable locking system eliminated torsional and bending slack, resulting in comparable mechanical performances between ILNn and plated constructs. The angle-stable locking mechanism of the new ILN eliminates all slack in the system; thus, interfragmentary motion will likely be reduced compared with standard ILN, which may improve the local environment for fracture healing.