Static Strength Tests Research Articles

Optimal design and experimental investigation of teeth connection joint on a filament wound composite transmission shaft

Abstract For limited weight reduction and avoidance of composite damage caused by the press mounting of the traditional metal teeth press-fit joint, a novel teeth connection joint technique of the fiber wound composite transmission shaft was investigated by theoretical analysis, finite element simulation, and experiment verification. Based on the mechanics of composite materials, the expressions of equilibrium torsional stiffness and static torsional strength were derived. According to the three-dimensional Chang-Chang failure criterion, its finite element model of progressive damage analysis was established through the user material subroutine. Applying the fast curing resin system, a typical sample of the structure was prepared through co-curing for the static torsional strength test, and its failure details of the fracture surface were observed by using a scanning electron microscope, which confirmed the validity of theoretical and numerical results. Based on this, the influence of the ply method and geometric characteristics on the failure strength was studied, and the optimal design of the joint was realized by the genetic algorithm. Compared with the press-fit joint, this structure reduces weight by 70 % under the same joint strength, which provides a new way for the connection of the composite transmission shaft.

Actual methods of full-scale metal-composite aircraft structures static testing with the use of information systems

AnnotationStrength testing of aircraft structures made of polymer composite materials requires improving methods and procedures for conducting experimental research. The paper presents a computational and experimental approach applied in the laboratory of static strength tests of FSUE “TsAGI”. The effectiveness of this approach is demonstrated on the example of testing the structure of medium-range aircraft. Before the tests, a computational model was created, based on which critical strength zones were determined. Additional strain gauges were installed in these areas, which allowed conducting thorough monitoring of the stress-strain state. The use of specialized software “Tensometry visualization module”, developed at FSUE “TsAGI”, made it possible to analyse the readings of ∼10,000 strain gages during testing in real-time, which significantly increased the information value of the experiment and reduced the risks of unintentional destruction of a full-scale specimen. Based on the results of the experiment, the calculation model was validated.

Are Strength Indicators and Skin Temperature Affected by the Type of Warm-Up in Paralympic Powerlifting Athletes?

(1) Background: the present study aimed to evaluate the effect of different types of warm-ups on the strength and skin temperature of Paralympic powerlifting athletes. (2) Methods: the participants were 15 male Paralympic powerlifting athletes. The effects of three different types of warm-up (without warm-up (WW), traditional warm-up (TW), or stretching warm-up (SW)) were analyzed on static and dynamic strength tests as well as in the skin temperature, which was monitored by thermal imaging. (3) Results: no differences in the dynamic and static indicators of the force were shown in relation to the different types of warm-ups. No significant differences were found in relation to peak torque (p = 0.055, F = 4.560, η2p = 0.246 medium effect), and one-repetition maximum (p = 0.139, F = 3.191, η2p = 0.186, medium effect) between the different types of warm-ups. In the thermographic analysis, there was a significant difference only in the pectoral muscle clavicular portion between the TW (33.04 ± 0.71 °C) and the WW (32.51 ± 0.74 °C) (p = 0.038). The TW method also presented slightly higher values than the SW and WW in the pectoral muscles sternal portion and the deltoid anterior portion, but with p-value > 0.05. (4) Conclusions: the types of warm-ups studied do not seem to interfere with the performance of Paralympic Powerlifting athletes. However, the thermal images showed that traditional warm-up best meets the objectives expected for this preparation phase.

INVESTIGATION OF RESIDUAL RESOURCE OF SPECIAL RAILWAY VAGON

The article examines the residual life of load-bearing metal structures (NMC) of special cars for the transportation of special contingent on the basis of the results of technical diagnostics and standard tests. Most scientific publications investigate the increase in the service life of different types of passenger cars by improving their design properties. The following methods are used in the study: resetting from wedges, resource tests for impact strength, impact tests, static strength tests. On the basis of carrying out technical diagnostics and standard tests the possibility of establishment of new appointed service life of cars is defined. The residual resource was set at one of the minimum calculated values obtained by mathematical dependence to calculate the residual service life. When determining the residual resource during the standard tests, the evaluation of the fatigue resistance margin was performed taking into account the stress of the load-bearing structures of the car during the tests. It is concluded that the condition of load-bearing metal structures of special wagons for transportation of special contingent after long operation does not approach the limit. The obtained practical and theoretical results make it possible to extend the service life of special wagons for the transportation of special contingent beyond the established by the manufacturer.

Design optimization of aircraft structures using virtual proving ground

The main challenges of aerospace industry are increased flight range, fuel, and operating costs. There is an urgent need for more efficient design methods and rational use of composite materials in order to reduce the weight of the aircraft and increase strength and reliability. The use of optimization methods, modern software, and supercomputer technologies plays a key role in shortening the product development cycle. It allows many design options to be analyzed and compared in the early design stages. This paper presents an approach to using optimization methods in conjunction with virtual tests. The Virtual Proving Ground (VPG) includes Virtual Testbeds (VTB) such as “Aerodynamics,” “Statics,” and “Dynamics.” VPG provides end-to-end transfer of results and boundary conditions between blocks and systems of automated post-processing of the results. Thus, the results of the aerodynamic tests are transferred as input data for the static strength tests. The results of static and dynamic tests allow to perform multicriterion optimization considering different loading conditions. Automated post-processing allows to track the miscellaneous parameters at every testing stage. The aim of this work is to develop an approach to optimization of a composite structures using VPG. The presented approach was developed and tested on the example of the unmanned aerial vehicle.

The fracture load analysis of different material thickness in adhesively bonded joints subjected to fully reversed bending fatigue load

The adhesive joints used in airframe and wing sections of aircrafts are generally subject to dynamic (fatigue) loading rather than static loading due to environmental conditions. The dynamic loading formed on wing sections of aircraft is generally in the form of fully reversed fatigue. This study experimentally and numerically investigated the lifetimes of single-lap joints (SLJs) of five different adherend thicknesses (2, 3, 4, 5 and 6 mm) – obtained using AA2024-T3 aluminum alloy and Araldite-2015 structural adhesive – under fully reversed bending fatigue loads. Accordingly, before performing fatigue tests, static bending strength tests were carried out on the SLJs to determine the maximum loads to be used for bending fatigue tests and also to evaluate their static performances. Fatigue tests were performed at a loading ratio (R) of −1 and a frequency of 4 Hz. It was determined that the static bending strength of the joints increased by approximately between 43% and 74% with increasing adherend thickness. However, this increase was not the same as the increase in material thickness. In addition, the increased adherend material thickness changed (decreased or increased) the maximum load applied to the joints over infinite cycles (taken to be 2 × 105 cycles). This was because the change in material thickness changed the bending moment formed in the joint and the flexural rigidity of the material.

The effects of adherend thickness on the fatigue strength of adhesively bonded single-lap joints

Different adhesive bonding methods have been prominently used in aerospace applications since the 1980s because adhesively bonded joints are regarded as an alternative to traditional bonding methods. However, the effects of fatigue on adhesively bonded joints – one of the most significant issues in the aerospace industry – are still currently being investigated. This study experimentally investigated the lifetimes of single-lap joints (SLJs) of five different adherend thicknesses (2, 3, 4, 5 and 6 mm) – obtained using AA2024-T3 aluminum alloy and DP460 structural adhesive – under varying tensile fatigue loads. Accordingly, before performing fatigue tests, static tensile strength tests were carried out on the SLJs to determine the maximum loads to be used for tensile fatigue tests and also to evaluate their quasi-static performances. The fatigue tests were performed at a loading ratio (R) of 0.1 and a frequency of 20 Hz. The static tensile strength of the joints was found to increase by approximately 22% with increasing adherend thickness. However, this increase was not the same as the increase in adherend thickness. In addition, increased adherend thickness was observed to change the maximum load applied to the joints over infinite cycles (taken to be 106 cycles). This was because the change in adherend thickness changed the bending moment formed in the joint and the flexural rigidity of the adherend.

Examination of structural properties of a new railway wagon design for flammable substance transportation

The article covers information from the field of static strength tests of freight wagons, in this case the static strength test was performed on a Zans 95 m3 tank wagon. The introduction of the article contains the division and significance of freight wagon tests. Various types of test load in static tests which affect the vehicle structure are also mentioned. Subsequently, the test requirements are written together with the technical parameters of the tested wagon. The next chapter deals with measured quantities and the instruments used for measurement, as well as a schematic sketch of the location of some sensors. The final chapter contains a description of the individual tests, where the procedure of loading, stay, unloading and reading of values for all static tests examined within the article are given. In the conclusion, verbal opinion is added to the summary of measurement results and the wagon construction is evaluated in terms of meeting the required strength conditions. The article contains graphs and tables from the outputs of some measurements.

A continuum damage model for composite laminates: Part IV- Experimental and numerical tests

This paper follows on from part III (Llobet et al., 2020) where a mesoscale continuum damage mechanics (CDM) model for composite laminates under static and fatigue loads has been presented. An experimental investigation on the damage occurrence and the strength of carbon/epoxy notched laminates subjected to static, tension-tension fatigue and residual strength tests is provided. X-ray inspections reveal that matrix cracking, longitudinal splitting and delamination control the fatigue degradation process. This paper presents a coupled computational model to account for intralaminar damage using the CDM model and interlaminar damage using a cohesive zone model (CZM). The capability of the computational model to capture the main fatigue degradation mechanisms and the residual strength is examined by simulating open-hole and double-edge notched specimens. The numerical predictions show that the main fatigue degradation mechanisms are well captured as well as the post-fatigue residual strengths except for the open-hole specimen. Further experimental and modelling work are required to develop a more reliable computational tool for quantitative evaluation of fatigue and damage tolerance of composite structures.

Analysis of the Corrosion Resistance of Aircraft Structure Joints with Double-Sided Rivets and Single-Sided Rivets

Abstract An important factor having a negative impact on the technical condition of aircraft structure elements is the adverse effect of the atmosphere, which causes formation of corrosion in aircraft structures, especially in riveted lap joints. The electric potential difference between the sheet material and the rivet, in the presence of humid air, may cause electrochemical corrosion. The paper presents specimens that imitate the repair on the Mi-24 helicopter with the use of blind rivets in places where solid double-sided rivets could not be used. The aim of the research was to assess the corrosion resistance of lap joints with the use of single-sided and double-sided rivets. The analysis of corrosion resistance was carried out based on accelerated aging tests in a salt spray chamber. The salt chamber tests were aimed at determining the changes taking place in the specimens exposed to the marine environment. In the course of periodic observations changes in the mass of the specimens and in the form of corrosion losses were recorded. These activities were aimed at determining whether the exposure of specimens in the salt chamber causes electrochemical corrosion or pillowing. In addition, the specimens were subjected to static strength tests to assess the effect of corrosion on the strength properties of riveted joints.

Методика проведения гидравлических испытаний полипропиленовых труб на разрыв стенки

Polypropylene pipes have a significant drawback – high values of the heat-stretch factor. Material properties are changing as the temperature rises, and material is exposed to increased pressure in the pipeline. In such a case, operation of polypropylene pipes is becoming unsafe. One of the known methods for heat-stretch reducing is reinforcement. Reinforcement is performed with aluminum foil or fiberglass. The properties of reinforced polypropylene pipes have not been fully investigating. Such pipes must go through a long operation cycle in order to enterprises could evaluate their properties, primarily such reliability characteristics as infallibility, maintainability, lifetime, and storability. There are no separate Russian National Standards for the properties and characteristics of polypropylene pipes, and for their types in Russia, as well as standard methods for hydraulic tests on destructive inspection at manufacturers. In industry, as well as in housing and utilities sector, are used pipeline valves of different purpose. Reliable and safe enterprise operation depends on the smooth running of equipment, pipelines and valves. In this regard, authors propose to consider valves and pipeline together at determining of reliability indicators. A method of destructive inspection is proposed, whereby the valves and the pipeline are tested together, that are corresponding to the most probable scenarios for the emergency development. The concept basic part includes the definition of a mandatory algorithm for destructive inspection actions during hydraulic testing of polypropylene pipes on a test load. Strength test methods for ball valves, pipelines and their joints have been described in the relevant Interstate, Federal or Industry Standards and Regulations. However, it is advisable to introduce additional standards for static strength testing of polypropylene pipes. The new standard will allow single out reinforced polypropylene pipes in a separate category, provide a definition for such pipes, and also take into account the influence of external factors on the condition of pipelines, their connections and valves.

Evaluation of Usefulness of AlCrN Coatings for Increased Life of Tools Used in Friction Stir Welding (FSW) of Sheet Aluminum Alloy.

The study presents the results of examinations of wear in tools made of 1.2344 steel without and with an anti-wear coating in the process of welding overlap joints of sheet metal made of 7075-T6 aluminum alloy using friction stir welding (FSW) technology. A commercial anti-wear AlCrN coating (Balinit® Alcrona Pro by Oerlikon Balzers Coating Poland Sp. z o.o., Polkowice, Poland) was examined, applied using physical vapor deposition (PVD) and used to improve tool life in metalworking processes. Wear tests for the tools were conducted in industrial conditions at specific parameters of the friction stir welding process. Tool wear was evaluated through examination of the tool working surface. The results of the static tensile strength tests and metallographic examinations of the joints were used to evaluate the effect of tool wear and the coating impact on joint quality. The results obtained in the study show that the tool made of 1.2344 steel was intensively worn after the welding of a joint with the length of 200 m, increasing the risk associated with further use of the tool and suggesting the tool’s low durability. The use of the AlCrN coating led to an increase in tool life. The coating limits the process of tool wear and can be used as an anti-wear coating for tools used in the FSW of aluminum alloys.

Investigation of the flat-clinching process for joining three-layer sheets on thin-walled structures

The flat-clinching is attracting increasing attentions in the field of lightweight structures because it does not form an exterior protrusion on the bottom sheet like the conventional clinching. In the present research, the flat-clinching process for joining the three-layer sheets is investigated through experimental methods. Sheet specimens were divided into two types based on loading characteristics and employed to produce joint specimens with different sheet configurations. The effects of the sheet configurations on the mechanical characteristics of the clinched joint were analyzed. This study consisted of five parts: the evolution of the forming force, main geometrical parameters, failure modes, static strength, and absorbed energy. The results show that five parameters can be employed to assess the joining reliability, where the neck thickness of the first interlock and the interlock width of the second interlock perform essential roles in the static strength and failure modes of the joint. In the static strength tests, the joint sample, in which the bottom sheet is clamped on its own while the middle and upper sheets are clamped together, exhibits higher static strength and absorbed energy than the joint sample where the upper sheet is clamped on its own while the middle and bottom sheets are clamped together. In addition, the joint specimens with different sheet configurations have different failure modes. The flat-clinching can join three-layer sheets by two interlocks to create a thin-walled structure.

Properties and anisotropy behaviour of a nickel base alloy material produced by robot-based wire and arc additive manufacturing

In order to produce three-dimensional components from metals, a wide variety of processes exist. Laser processes combined with metal powders are frequently used and developed. Restrictive factors are the machine-related small workspace, the machinery costs and the material portfolio, which place the technology in the area of high-performance components. Wire and arc additive manufacturing (WAAM), as a robust and economical welding process technology in combination with robot applications, represents an option to become more size-independent and provides variability in the range of materials. This work shows results for the robot-based WAAM of structures made from nickel alloy 617. The main focus of the investigation was the determination of the mechanical properties in the as-welded state for which static strength tests, microhardness and metallographic studies were carried out. The anisotropic material behaviour in relation to the build direction (BD) was tested. The direction-dependent strength properties of single-track welded structures are presented with samples taken and tested at 0°, 45° and 90° to the BD. The deformation behaviour was investigated by micro-tensile tests in a scanning electron microscope, whereby the formation of sliding steps on the polished surface under tensile stress was studied. The anisotropic behaviour of the WAAM structures is discussed under consideration of the microstructure and with regard to the grain size development and phase formation. The results indicate an anisotropic material behaviour in the as-welded state based of the crystallographic orientation of the material.

An investigation into the mechanical behaviour of fibre-reinforced geopolymer concrete incorporating NiTi shape memory alloy, steel and polypropylene fibres

This paper studies the use of nickel-titanium (NiTi) superelastic shape memory alloy (NiTi-SMA), steel, and polypropylene (PP) fibres as reinforcement in geopolymer concrete (GPC) to improve the overall mechanical properties. NiTi-SMA, steel and PP fibres were added to the GPC at the fibre volume contents of 1.00%, 0.75% and 0.50% for steel and NiTi-SMA and 0.20%, 0.15% and 0.10% for PP. In this study, workability, compressive strength, splitting tensile strength, modulus of elasticity, static flexural strength and cyclic flexural tests were conducted to investigate the behaviours of steel fibre-reinforced GPC (SFRGPC), NiTi-SMA fibre-reinforced GPC (NiTi-SMAFRGPC) and PP fibre-reinforced GPC (PPFRGPC). The results showed that the mechanical performance of FRGPC increased with the increment of steel and NiTi-SMA fibres, but deceased with the increment of PP fibre. SFRGPC mixes exhibited the largest compressive strength (39.39 MPa), splitting tensile strength (5.36 MPa) and flexural strength (12.53 MPa), whereas NiTi-SMAFRGPC mixes presented the superior cyclic flexural performance which showed the smallest residue deformation and largest re-centring ratios in four cycles in comparison with SFRGPC and PPFRGPC mixes.

Static Strength Tests for Physical Education of Students with Chronic Health Conditions: Metrology Assessment

Static Strength Tests for Physical Education of Students with Chronic Health Conditions: Metrology Assessment

Comparative Risks of Hydrostatic and Pneumatic Pipeline Testing

Abstract An important step in a pipeline-construction project is confirming that the piping and facilities are adequate for the expected operating pressures via static strength tests. All fluids have mass and internal energy. Fluids under pressure have significantly elevated internal energy. All fluids are compressible to some greater or lesser extent, and the fluid added to raise the pressure of the fluid in the bulk volume adds significant energy. The raw mass of a fluid must be considered when evaluating terrain elements and support elements (i.e., pipe stands and pipe racks). The selection process for a test fluid should always endeavor to minimize the total risk of the entire process. Code-guidance has historically not shown a clear preference for the selection of one particular test medium over another. Some jurisdictions have written regulations that step away from ASME guidance and do show a clear preference for hydrostatic testing over pneumatic testing. This preference manifests itself in several ways, but the primary representation is the requirement in statutes and regulations that a pneumatic test should have an “exclusion zone” around the test to reduce the risk of injury during the test. These documents tend to not have an exclusion-zone requirement for hydrostatic tests. This paper is undertaken to demonstrate the relative risks of liquid versus gaseous test media and presents a background of why pneumatic tests have been singled out by regulators as higher risk and shows why this regulatory preference can result in increasing risk rather than decreasing it.

Analysis of strength and deformativity of glass plate joints under static loading

The weak point of any structure is always the elements junction node. This article presents the results of a study of the adhesion of glass plates interconnected over the entire surface by means of adhesive materials and triplex technology under the action of static loading. The bearing capacity and deformability of such joints was established. For the research purposes there were designed, manufactured and tested 6 series of prototypes. Thus, the object of the study is 6 series of test specimens for testing the adhesion of glass plates to each other. The prototypes consisted of three glass plates, each 10 mm thick, interconnected by means of triplex technology and various adhesive materials. Before bonding, the glass plates of the prototypes of I–V series were cleaned of dirt and degreased. The adhesive was applied to the entire surface of one plate. Then, the glass plates were firmly interconnected with the help of the vise and held for 5–10 minutes. The curing time depended on the adhesive materials. The curing of the glue of the prototypes of the fourth and fifth series was done under the rays of an ultraviolet lamp. The plates of the sixth series prototypes were interconnected by triplex technology, where EVASAFE polymer film (Bridgestone, Japan) was inserted between the plates and the prototypes were heated to 130 ºC and held for 30 minutes.An experimental research program was developed. The test rig consisted of a stand for static structural strength tests. The external load N was applied by means of a hydraulic jack and was performed step by step. The magnitude of the load was 1.0 kN and was monitored using dynamometer for the I–V series prototypes and a ring dynamometer for the VI series prototypes until the complete destruction of the prototype. At each load stage a 10 minutes exposure was performed followed by gauge reading. On the basis of the obtained results, an analysis of glass plates adhesion was performed and an averaged dependency graph of shear deformations and tangent stresses τ=N/A for the series of the prototypes was constructed. This provides the ability to obtain strengths and deformations for a series of prototypes.

A Comparative Study between Commercially Available Type 1 Plywood and Plymer, a HDPE and Pineapple Leaves Composite

Pineapple in the Philippines, with an annual production rate of more than 2 million tons, is ranked the third largest pineapple producing country in the world, with 172,000 acres dedicated to its production. Under this scenario, pineapple is a subtropical fruit with a considerably higher proportion of by-products consisting of peels, stems and leaves, leading to a high production of agricultural waste. In particular, pineapple leaves fiber as one of the most abundant by-products rich in cellulose. The researchers compared the properties and composition of commercially available type 1 plywood to a mixture of high density polyethylene plastic chips with dried pineapple leaves called Plymer. The ratio of the Plymer was 80 % HDPE and 20 % leaves. The series of tests carried out by DOST-FPRDI were screw removal, static bending and tensile strength. The researchers used the statistical tooltest to compare the results of the test. In conclusion, Plymer is the best option for static bending and tensile strength testing.

필라멘트 와인딩 공법에 의한 30m급 굴절형 고소작업차용 유리섬유/에폭시 복합재 붐 개발에 관한 연구

Since electric energy is used in industry, mass production and various conveniences are provided. To provide convenience for the construction and operation of such electric energy transmission and distribution facilities, it is increasing that the demand for special purpose vehicles, that is, telescopic aerial work platform vehicles. When working active electric work using the telescopic aerial work platform vehicles, due to active electric work is inevitable, it is essential to ensure insulation performance for the safety of the operator. In this paper, we study the design and development of mechanical properties for filament winding process of glassfiber/epoxy composite, it is required to boom of telescopic aerial work platform vehicles. The glass fiber/epoxy composite filament winding process and its mechanical properties were evaluated to replace the existing ATOS80 boom. By filament winding process it was obtained the mechanical properties required for the design analysis of the glass fiber/epoxy composite boom. Using this, the insulated boom for the 30m class aerial work vehicle was designed and was manufactured by applying the filament winding process. The fabricated composite boom was evaluated by the static strength test to meet the required strength. The maximum displacement was 84mm and the crack occurred at the maximum load of 8981N. It satisfied the maximum lifting load of 4900N and 210mm the maximum displacement required for the boom.