Types Of Bolts Research Articles

Comparative study on mechanical performance of bolted joints with steel and fibre reinforced polymer bolts

This paper presents a comparative study on single-bolted double-lap joints with steel bolts and glass fibre reinforced polymer (GFRP) bolt. Three types of steel bolts including plain, galvanised and stainless and a newly developed GFRP bolt were considered. Two preload levels were practiced in the experiments, i.e. snug-tight and full-tensioning. The torque-preload relationships for different types of bolts were investigated in reference to international standards. It was found that galvanised bolt showed the highest efficiency of torque conversion into bolt preload, while the GFRP bolt the lowest. Static experiments and finite element (FE) analysis were then conducted and the mechanical performance of bolted joints with steel and GFRP bolts in shear were comparatively studied in terms of failure modes, load-displacement and load-strain responses. Similar joint stiffness or capacity was found for the joints with GFRP or steel bolts under snug-tight condition. High preload level can significantly increase the joint capacity by up to 89.2% for bolted joints with steel bolts while only 9.8% for GFRP bolted joints. The developed FE modelling considering contact behaviours and pretension can well predict the mechanical behaviour of single-bolted double-lap joints including initial slip.

Numerical study on the resistance of thread-fixed one-side bolts: Tensile and bearing strength

In steel structures, owing to technological aspects, frequently bolting access is difficult. To overcome these issues, technological research has proposed in the last decades several blind bolt systems that allow the installation of a bolt working only on one side of the connection. The simplest type of blind bolt is the thread-fixed one side bolt (TFOSBs), in which the connecting elements are fastened through threaded holes, and the connection is assured by the contact between bolt and hole threads. This type of bolting system is very easy to apply, but, currently, there are only a few design rules available.While the mechanical behaviour of TFOSBs is conceptually easy to understand, there are still some specificities that need to be accounted for and deserve specific investigations. A first aspect regards the behaviour in tension that must be characterized properly because it depends on some local effects such as the threads’ bending both bolt and hole. Similarly, regarding the behaviour in shear, due to the lack of confinement in the nut area, as already shown for similar bolt typologies, the bearing resistance may be lower compared to standard assemblies. To provide design rules for the behaviour of TFOSBs in tension and shear, in this paper, FE models and parametric studies are developed. The collected data are used to provide a prediction of the resistance of these fasteners, suggesting design rules of immediate applicability developed along the same lines of Eurocode 3 part 1.8 provisions. The results obtained suggest that, compared to standard bolt assemblies, an average reduction of 15% of the bearing resistance should be considered for the design of TFOSBs. Instead, for what regards the behaviour in tension, the shank necking failure of the bolt be achieved only by assuring minimum bolt screwing depths, which are suggested in this paper, confirming similar proposals already available in technical literature. Conversely, provided that the failure of the hole’s threads is accepted a reduction coefficient of the tensile resistance to be used in design, ranging from 0 to 1, has been proposed based on the FE studies’ results.

Cyclic behaviour and hysteretic model of austenitic stainless steel bolted T-stubs

The aim of this paper is to investigate the hysteretic behaviour of stainless steel bolted T-stub connections. A total of 22 bolted T-stubs in austenitic grade EN 1.4301 were tested under monotonic loading and cyclic loading under both variable and constant amplitudes. The tested T-stubs were carefully designed with two different bolt configurations and were fabricated with two types of stainless steel bolts – A4–70 and A4–80 thus allowing different failure modes to be obtained. Three additional bolted T-stubs in carbon steel grade Q345B were used as benchmark specimens to facilitate a direct comparison of the performance of carbon and stainless steel T-stubs under cyclic loads. Monotonic loading tests were conducted to acquire basic parameters of the cyclic loading protocols employed in the cyclic loading tests. The hysteretic responses of the tested T-stubs under two variable amplitude loading histories and three proportional constant amplitude loading histories were recorded and were further analysed in terms of failure characteristic, hysteresis response, skeleton curve, energy dissipation and strength degradation. Based on the evolution of the hysteresis curves, standard hysteresis loops were acquired and were used to develop a novel hysteretic model able to simulate the initial loading branch, the unloading branch and reloading branch of the hysteretic response. It has been demonstrated that the developed hysteretic models provide a close agreement with the obtained experimental results and can thus be used to estimate the expected energy dissipation of bolted stainless steel connections subjected to cyclic loads.

Study on Mechanical Properties and Application of a New Flexible Bolt

As mining depth extends continuously, complex geological environment and strong mining stress pose serious challenges against excavation safety and higher demand for bolt support. To meet the challenges, a new type of flexible bolt is developed that is free from the limitation of excavation height and can be installed quickly. The flexible bolts have a tail structure which is squeezed together by the locking casing and the steel-strand rod. The tail structure forms the thread through the rolling process, and then can be quickly installed by the nut rotation type, which avoids the disadvantages of the cable tension installation. Through the flexible long bolts, the thick anchoring layer of the roof can be constructed, and the safety control of the roadway is realized. To obtain the optimal specifications, locking casings of three diameters and lengths were used to prepare bolt samples for static tensile test. Test results show that when the diameter of locking casing is fixed, the peak resistance increases as the length of locking casing increases, but the increased amplitude tends to reduce gradually. When the length of locking casing is fixed, too large a diameter makes the mechanical property unstable. Finally, the optimal length and diameter of locking casing are set at 120 and 30 mm, respectively. In addition, cyclic loading tests were conducted, the results of which indicate that cyclic loading does not change the stress state within the bolts and that flexible bolts display a stable mechanical property. Field results indicate that flexible bolts achieve low damage of the surrounding rock and control the maximum roof fracture depth within 2.1 m, thus guaranteeing the roadway safety.

Experimental study on stainless steel high-strength bolted slip-resistant connections

Stainless steel structures have broad application prospects owing to their excellent corrosion resistance and mechanical properties. Current studies on stainless steel structures mainly focus on material properties and member behaviors. Several studies have reported on the performance of stainless steel joints and connections. In this study, a series of tests were performed on two fundamental parts of the stainless steel high-strength bolted slip-resistant connection, that is the stainless steel high-strength bolts and stainless steel faying surface treatment. For the stainless steel high-strength bolts, the tests were conducted on six types of bolts, including a new type of high-strength bolt made of S17400. The chemical compositions and full-range stress-strain curves were reported. The friction coefficients of the bolts with and without lubrication were measured. It was concluded that thread galling would probably occur during the application of the preload for bolts without lubrication. Lubricants would smoothen the tightening process and reduce the friction coefficient considerably. With regard to the stainless steel faying surface treatments, a total of eight types of treatment methods categorized into four groups were investigated. The surface roughness and slip factor were measured. It was concluded that under the commonly used steel structure faying surface treatments, the slip factor of the stainless steel plate was much lower than that of the carbon steel plate. The methods of clamping soft metal plates between the grit blasted stainless steel surfaces could improve the slip factor to approximately 0.30; a higher slip factor with a comparatively lower surface roughness would be obtained with the coating method. The proposed heavy brushing and mechanical scoring methods could considerably increase the surface roughness and slip factor. In addition, the slip factor was positively correlated with the surface roughness for most of the faying surfaces. The results of this study could benefit the development of related design codes.

Field Experiment Research of the Polycystic Aeration Bolt: Model Design and Anchorage Mechanism

As a new type of bolt, the polycystic aeration bolt has a broad application prospect in soft soil area; however, its design and production are still in the stage of constant exploration and improvement. From the perspective of bolt material and engineering cost, the important components of the polycystic aeration bolt were analyzed by combination with the existing bolt models, and a new structural design scheme of a kind of polycystic aeration bolt which can be used in practical engineering was presented in this paper. Then, the stress and failure mode of this bolt were discussed, and the theoretical equation of the bearing capacity was derived by using the elastic‐plastic theory. In addition, the assembly and fabrication technology of this bolt in practical foundation pit engineering was described in detail. Finally, the field pull‐out test of the polycystic aeration bolt was carried out, and the test results were compared with those of the conventional grouting bolt, which indicated that this new bolt has a greater advantage in bearing capacity than the conventional grouting bolt, verifying the feasibility of the structural design scheme of the polycystic aeration bolt proposed in this paper.

Development of a Lever Mechanism for Loading a Suspended Conveyor

The issue of mechanization of hanging of long components of self-installing rock bolt (SIRB) type has been considered. The possibility of usage of slider-crank mechanism for these purposes has been proved. Linear dimensions of lever mechanism that meet the requirements defined by the applied motor and SIRB parameters have been determined on the ground of parametric synthesis. The performed force analysis has proved the application of fluid power drive.

Competitive Failure of Loosening and Fatigue of Bolts under Composite Excitation

At present, research on the loosening of bolts under transverse excitation and their fatigue under axial excitation has been relatively mature, but research on the competitive relationship and failure characteristics between loosening and fatigue of bolts under transverse and axial composite excitation is still insufficient. Therefore, a method to accurately determine the failure types of bolts is proposed in this study by conducting a competitive failure test of loosening and fatigue under composite excitation. According to this method, the failure types of bolts can be distinguished. The analysis results reveal that there is an obvious competitive failure relationship between the loosening and fatigue of bolts, and the failure mode is mainly affected by the ratio of the transverse and axial loads (ξ). There is a critical ξ of bolt‐loosening or fatigue failure, and the critical ξ is an inherent property of the bolt and is unrelated to the load. The critical ξ of 8.8 grade M8 × 1.25 × 70 high‐strength bolts under composite excitation is obtained as 0.075 mm/kN. The failure mode of bolts under composite excitation can be predicted based on the critical ξ.

An Optimized Permanent Magnet Brake Mechanism in Robot Joints

This paper proposes a novel brake mechanism in robot joints, especially for space robot joints which require low power consumption and high reliability. The key point of the brake mechanism is that the torque spring is replaced with the Nd-Fe-B permanent magnet. Due to the position and force relationship between the permanent magnet and the electromagnet in the brake mechanism, the stroke of the brake armature can be extended so that the bolt type brake structure is adapted and the braking torque can be infinite theoretically. Meanwhile, the holding current in the electromagnet can be decreased to save energy and reduce heat generation. The magnetic circuit models of the electromagnet and permanent magnet in the brake mechanism are established and analyzed. In order to improve the response speed of the brake mechanism, a novel H-bridge brake power supply circuit is proposed. To verify the benefits of the design, a permanent magnet brake prototype with the H-bridge power supply circuit is set up. While the holding current is consistent with the peak current in the conventional torque spring motor brake, the proposed permanent magnet brake mechanism can decrease the holding current below 0.1 A.

Assessment of Rotational Accelerometer Mountings for Rotational Frequency Response Function Measurement

Kistler Kshear 8840 piezoelectric rotational accelerometer is designed with an M5 bolt type of mounting and a 5mm diameter of through or pre-tapped hole is required in a structure under test. However, the mounting is not applicable for some cases, and other types of mounting need to be used. This work investigates the applicability and accuracy of five different configurations of mounting for Kistler Ksher 8840 piezoelectric rotational accelerometer for the measurement of the rotational FRFs of a steel plate. The mounting configurations consist of 3D printed PLA and ABS mounting, bee’s wax, steel, and bolt mounting. The rotational FRF of the steel plate was measured by using impact testing method. The applicability and accuracy of the mountings were evaluated by comparing the measured FRFs with the finite element (FE) FRFs counterparts. The comparisons of the results revealed that using the bee’s wax mounting had produced the most accurate and least noisy FRF. It was also found that using the 3D printed PLA mounting had contributed to the highest contamination of noise and several spurious peaks in the measured FRFs. These findings provide useful information for selecting the appropriate types and designs of mounting for the Kistler 8840 rotational accelerometer.

Bolted connected optimization of composite-to-aluminium structure based on vibro-acoustic control: Numerical simulation and experimental

Bolted connection is an important connection form between composite laminate plate and metal frame structure. The type and location of the connection bolts are of great influence on the structural strength, stiffness and structural vibro-acoustic properties. To achieve the goal of reduction vibration and noise, the bolted connection form optimization of the panel structure is investigated. Bolts stiffness parameter (bolt diameter, etc) and the distribution location are defined as design variables, the bolted connection form optimization function which aim to minimize of acoustic radiation power is established. The composite-to-aluminium panel structure under harmonic excitation for example, the numerical analysis of bolted connection form optimization is implemented. The results show that the acoustic radiation power level and total level of the panel structure are significantly decreased. In the end, the numerical analysis results are verified by model experiment, which validated the feasibility and effectiveness of the proposed method. The results in present work provides more understanding the design and application of the composite-to-aluminium panel structure with bolted connection.

Study of Separation Mechanism and Characteristics of Ridge-Cut Explosive Bolts Using Numerical Analysis

Ridge-cut explosive bolts are a type of pyrotechnic release devices in which two connected structures are separated by explosives. They are designed such that shock waves can interact with and cut their body. Furthermore, they provide a clean separation surface and require a smaller explosive amount compared with other types of explosive bolts. In this study, ridge-cut explosive bolts of various diameters and with an exploding bridge wire (EBW) detonator were developed for use in sled testing. Their initial shapes were designed using an established procedure. Initial separation tests for the initial designs of the explosive bolts showed that considerable debris was produced for some models and that the explosive amount should be reduced. For the minimization of the number of experiments, the appropriate explosive amount was determined in advance through numerical analysis, which was performed using Autodyn, a commercial hydrocode. The numerical analysis technique used was improved to analyze the complete separation phenomena. The numerical results clearly revealed the separation mechanism and characteristics of the explosive bolts and helped determine an appropriate explosive amount for achieving a small amount of debris. Verification tests confirmed that explosive amounts determined using the numerical results were appropriate for separation and generated a small amount of debris.

Effect of bond and bidirectional bolting onhysteretic performance of through bolt CFST connections

Through bolt connections in Concrete Filled Steel Tubes (CFSTs) has been proved to be good in terms of seismic performance and constructability. Stiffened extended end plate connection with full through type bolt helps to avoid field weld altogether, and hence to improve the quality of joints. An experimental study was conducted on the hysteretic performance of square interior beam-column connections using flat extended end plates with through bolt. The study focuses on the effect of the bond between the tie rod and the core concrete on the cyclic performance of the joint. The study also quantifies how much the interior joint is getting strengthened due to the confinement effect induced by bi-directional bolting, which is widely used in 3D moment resisting frames. For a better understanding of the mechanism and for the prediction of shear capacity of the panel zone, a mathematical model was generated. The various parameters included in the model are the influence of axial load, amount of prestress induced by bolt tightening, anchorage, and the concrete strut action. The study investigates the strength, stiffness, ductility, and energy dissipation characteristics. The results indicate that the seismic resistance is at par with American Institute of Steel Construction (AISC) seismic recommendations. The bidirectional bolting and bond effect have got remarkable influence on the performance of joints.

체결력이 개선된 대형 트럭용 풀림방지 평행 세레이션 형태의 휠 볼트 설계에 관한 연구

To develop an anti-releasing wheel bolt for large trucks, the parallel serration (PS) type wheel bolt is introduced as an alternative for conventional saw blade (SB) type one. The forming load was analysed using FEM solver program according to the radius of curvature at the corner of serration top. The serration die for a PS type bolt which was designed with the possibly largest curvature radius (R) showed the lowest forming load at the top area of serration corner and PS type bolt die with R = 0.4 mm showed 1.6 times longer life cycle compared with SB type die. The PS type bolt revealed also higher clamping force and axial force compared with the SB type bolt.

Tensile bearing capacity for bolted spherical joints with different screwing depths of high-strength bolts

Aiming at evaluating the reliability of the high-strength bolts’ fake tightened-up phenomena of the bolted spherical joints in a spatial grid structure, this research studied the tensile strength, stiffness, and failure modes of the bolted spherical joints with different bolt types and screwing depths using a combined method of the lab experiments and numerical simulations. A total of 40 axial tension tests of the bolted spherical joints were conducted with five different bolt types and eight different screwing depths. The test results showed that the bolted spherical joints with the different bolt screwing depths of high strength bolts suffered three failure modes, namely, the thread failure, bolt fracture failure, and sphere rupture failure. Validated by its feasibility and accuracy, the proposed numerical simulation method of the bolted spherical joints can estimate the ultimate strengths and failure modes, as well as the detailed stress distribution and failure development process. According to the test and numerical analysis results, a group of calculation formulas was developed for predicting the tensile strength of bolted spherical joints with different bolt screwing depths.

The mechanism’s study of fixing a container on a freight wagon type Rgs

In freight transport is constantly evolving in the world. An important role in development of freight transport is the increasing usually a speed to 180 km/h of freight trains. In multimodal transport, all the goods are transported in containers. Therefore, the freight is mostly containerized. Several containers in freight trains are transported on Rgs freight wagons. On Rgs platforms of freight wagons are bolts of which the containers are fixed. The role of these bolts is very important because when the train takes the curve or brakes ward, containers could leave the wagon’s platform. In this paper, we represented a Rgs Wagon loaded with two containers. We have to mention that the dimensions of wagon and containers have been made using original projects. Furthermore, we are approached the theoretical aspects referring to the clamping system. We set out to accomplish a through search of both the used bolt to Rgs wagons and new model of bolt. This research was caried out with the help of finite elements method. The design part and the study with finite elements were made in NX 12 software from Siemens. Because of these bolts types they following stress: normal, shear and von Mises. As a consequence, we deduced that the second bolt type is more reliable.

Simulational and experimental study of stress in bolts work-piece

In order to study the effect of different bolts tightening sequences on the stress of bolts work-piece, the finite element simulation and stress test experiments are adopted. Three types of bolt work-piece: two, five, and frame type bolts work-pieces are studied under different tightening sequences. The stress values and distribution are obtained under different tightening sequences by simulation. It is observed that the stress distribution tendency of bolts work-piece has little change under different tightening sequences. It also notices that the tightening sequences have no effect on two bolts work-piece due to the symmetry of work-piece. In five bolts work-piece, the variation range of stress under tightening from ends to middle is smaller than that under sequence tightening, which indicates that better stress uniformity is obtained under tightening from ends to middle in five bolts work-piece. Similarly, in frame bolts work-piece, the variation range of stress under symmetrical tightening is smaller than that under sequence tightening, which indicates that better stress uniformity is obtained under symmetrical tightening in frame type bolts work-piece. Furthermore, the experimental results are in good agreement with the simulation results. Moreover, the stress variation mechanism is revealed by analyzing residual preload variation under sequence tightening.

Experimental study on shear performance of composite cold-formed ultra-thin-walled steel shear wall

Cold-formed ultra-thin-walled steel shear wall shows excellent performance. The house constructed using the cold-formed ultra-steel shear wall is composed of continuous single-layer walls, including the floor joints between wall segments. The wall is coordinated to deform through floor joints and the weak part is located at the floor joints. In this paper the test results of nine TCS walls (upper and lower adjacent composite cold-formed ultra-thin-walled steel shear interior wall including floor joints) are reported. The effects of different factors, including axial compression, section height of stud, type of anchor bolt, under cyclic loading on the shear performance of TCS walls are discussed. The results show that, the existence of the axial compression accelerates the screw failure, resulting in reduced bearing capacity. The section height of the wall stud and axial compression of the wall have greater effect on the bearing capacity of TCS wall. Engineers should pay more attention to the influence of wall axial compression. TCS wall experiences progressive damage of multiple components. The degradation of the bearing capacity and stiffness are relatively slow. Cumulative damage is the reason why the TCS wall could not continue to carry loading. For TCS wall with the two nuts on one anchor bolt, screws bear tension-shear action after anchor bolt tilts, and thus the screws and the anchor bolt fail rapidly. After the addition of spatial steel bar truss at the floor joints, the screws only bear the shear force, which improves the wall resistance to damage.

Numerical investigation of bolt anchorage with tension force and shear force

The bolt anchorage with tension force and shear force are studied numerically by FLAC3D modelling. A tri-linear material model was utilized for the bolt steels in order to simulate the strain hardening behaviour of the materials. The numerical modelling show that different types of bolts have similar load capacities, while their deformation capacities are different. The numerical results match the laboratory test results. The different deformation capacities of rock bolts are attributed to their different bonding conditions and stretching lengths. The axial load in the rebar bolt reduces exponentially from the loading point close to the joint to the bolt end. The axial load in the D-Bolt has its maximum at the joint and reduces slowly as the distance from the joint increases.

Stainless steel bolts subjected to combined tension and shear: Behaviour and design

Stainless steel (SS) bolts have become increasingly popular in steel construction industry primarily due to their excellent corrosion resistance and compatibility with other SS structural members. However, to date there is still very limited knowledge on the mechanical behaviour of these types of bolts as structural connections. As a result, practical design guidelines for SS bolts are direct extrapolation of those of carbon steel bolts. Moreover, these guidelines were initially proposed for most commonly used SS bolt grades, i.e. austenitic bolts with property class up to 80 (800 MPa ultimate strength), while their applicability to higher strength and duplex SS bolts are still not clear. To close the gap, this study presents detailed experimental and numerical investigations on the behaviour of austenitic and duplex SS bolts under combined tension and shear, with an emphasis on high strength grades (with ultimate strength higher than 800 MPa). Three phases of experiments were conducted including machined coupon tests, pure tensile tests, as well as combined loading tests. The failure mode, strength and ductility of SS bolts under different combinations of tension and shear were evaluated based on test results. In addition, finite element models were applied to simulate the behaviour of SS bolts up to final failure. Detailed numerical analysis was thereafter carried out to extend the experimental database and study the effects of a few key parameters which were not included in the experiments. Based on the available test and analytical data, the applicability of existing design methods was assessed in predicting the strength of SS bolts (including both common and high strength grades) under combined loading. Improved design formulae were proposed accordingly.