Prevent Plastic Deformation Research Articles

Tribocorrosion and Mechanical Properties of Nanotubes Grown on Ti–35Nb Alloy by Anodization

Abstract In this study, we evaluated the tribocorrosion and mechanical properties of nanotubes grown on a Ti–35Nb alloy. The nanotube arrays, approximately 2.0 µm thick, were formed through controlled anodization and annealing, composed of Ti and Nb oxides. The compact oxide film at the nanotube/substrate interface provided corrosion resistance, lubricating properties in worn tracks, and improved wear resistance. The nanotubes exhibited a lower coefficient of friction, hardness, and elastic modulus compared to untreated Ti–35Nb. The crystalline structure of the nanotubes and the oxide interface layer enhanced adhesion, preventing plastic deformation and improving tribocorrosion resistance.

Open-atmosphere laser nitriding of austenitic steels to form wear-resistant surfaces

This study presents an interesting result based on the laser beam irradiation of austenitic steels in an open atmosphere, which enables the formation of a surface layer comprising a nitrogen solid solution rather than an oxide. First, a focused nanosecond pulsed Nd:YAG laser beam with a laser energy of 400 mJ·pulse−1 was used to irradiate an AISI 316 stainless steel. This formed a surface layer of ~3 μm thickness with ~12 at.% nitrogen solid solution, thereby enhancing the hardness of the AISI 316 stainless steel surface to ~380 HV, nearly twice that of the untreated surface. Consequently, wear resistance was improved by preventing plastic deformation and abrasive wear. Thereafter, similar laser beam irradiation of Inver42® and Kovar® steels resulted in the formation of nitrogen solid solution layers with a thickness of ~1.5 μm, which is lower than that of AISI 316 steel. Furthermore, their nitrogen contents were reduced to ~6 at.%. Consequently, the improvement in the surface hardness of the Inver42® and Kovar® steels was less than that of the AISI 316 stainless steel. These differences were attributed to their alloy compositions; for instance, Cr, which has a high affinity for nitrogen, might trap the available nitrogen, thereby contributing to an increase in the nitrogen content.

Non-Destructive Disassembly of Interference Fit under Wear Conditions for Sustainable Remanufacturing

Remanufacturing has been gaining increasing attention in the last few years as a part of green engineering. It is the process of restoring the original specifications of a given product utilizing a combination of new, repaired, and old parts. The present study investigates non-destructive disassembly of an interference fit pin-hub joint to enable the reuse of worn parts with the same loading capacity. The aim is to reduce the disassembly force while preventing plastic deformation and frictional damage on the contact surface to avoid fretting failure and enable further coating. A finite element model of a shaft/hub interference fit was developed, taking into account two cases of damage to the mating parts: deformation and corrosion. The results indicate that thermal disassembly is effective in reducing breaking force by 50% in deformed joints, whereas vibration waves are more suitable for corroded parts with increased friction. In addition, applying a low-frequency oscillation force to the axis of disassembly reduces the pulling out force by 5% and plastic deformation by 99% due to acoustic softening effects. Furthermore, using a heat flux simultaneously with vibration decreases the breaking force by 85%, indicating the higher effectiveness of thermal-aided disassembly and vibration-assisted disassembly in reducing the breaking force of corroded parts with increased friction. This study provides remanufacturing designers with efficient tools to weaken the interference fit and decrease the disconnecting force, ultimately reducing the cost and time required for the disassembly process.

Matching analysis and experimental study of mechanical properties of cement sheath interface

The cement sheath interface is an important component of the wellbore barrier system. A mismatch between the interfaces of the cement sheath may result in leakage. This paper presents a method for assessing cement sheath interface adaptability based on the Dundrus composite parameter method, and the corresponding test flow for evaluating cement sheath integrity is provided for verification. According to the calculation results, stress concentrations are more common at the first interface of the cement sheath. The second interface is relatively unaffected by stress concentration under the same working conditions as the first interface. Stress concentration at the interface can be effectively alleviated by increasing the elastic modulus of the cement sheath or decreasing the Poisson's ratio. However, if the elastic modulus of the cement sheath increases, the cement sheath will be more susceptible to plastic deformation, and the strength coefficient of the singular stress field at the interface will decrease by approximately 10%. As a result, reducing the Poisson's ratio of the cement sheath effectively reduces stress concentration at the interface end. Especially in sandstone formations, the strength coefficient of the singular stress field at the interface can be reduced by 63% at most, resulting in a good interface adaptability. As a result of the above calculations, three groups of cement slurries with different mechanical parameters were selected and tested. As expected, the test results confirmed the applicability of the method. In light of the above results, cement slurry engineers should factor in the stress singularity effect when designing cement slurry systems. To prevent plastic deformation, high-strength and low-elastic cement should be employed, and the Poisson's ratio should be appropriately reduced in order to prevent interface stress concentration, thereby ensuring the integrity of the cement sheath in an increasingly harsh downhole service environment.

Mechanical properties of meteoritic Fe–Ni alloys for in-situ extraterrestrial structures

A critical requirement for outposts and settlements on the Moon and Mars is the use of in-situ resources to create pressurized, human-rated habitats with low mass (i.e., high tensile strength), high reliability (i.e., high toughness) and easy processability. This study assesses the capability of binary Fe–Ni alloys - with Ni content of 5–11 wt%, typical of M-type asteroids and iron meteorites - to meet these requirements. We measure the hardness and tensile properties of these Fe–Ni alloys at 21 °C in the as-cast state (representative of melted and cast meteorite material), with grain sizes of ∼90 μm. As the Ni concentration increases from 5 to 11 wt%, strength increases near linearly: from 260 to 440 MPa for the yield stress, and from 340 to 560 MPa for the ultimate tensile strength. Ductility however decreases, also near-linearly, from 20 to 3%. The yield stress of Fe-(5,7,9)Ni alloys, measured between −89 and 21 °C (relevant to the Moon and Mars), increases steeply with decreasing temperature. The temperature-dependence of the yield stress for these alloys - as well as pure Fe, Fe-1.4Ni and Fe-2.9 Ni alloys from literature - is fitted to an Arrhenius-like model, allowing to extrapolate yield stress values of Fe–Ni alloys for the full range of Lunar and Martian temperatures. A pressurized habitat consisting of flat plates of Fe–Ni alloy welded into a half cylinder (Quonset hut, with 5 m radius and 10 m length) is modeled via finite element analysis to determine the plate thickness (and thus alloy mass). For the above ∼400 m3 habitat with a 1 bar atm on the Moon or Mars, the thickness of the Fe–7Ni plates can be as low as 10 mm to prevent plastic deformation of the alloy. This plate thickness corresponds to 20–30 iron-nickel meteorites with ∼½ ton mass, as observed to exist on Mars by NASA rovers. This confirms the feasibility of using Fe–Ni meteorites - after in-situ collection, melting and casting – to create metallic sheets which can be welded into pressurized structures, at low energy and infrastructure costs.

Innovative Control Technique for the Floor Heave in Goaf-Side Entry Retaining Based on Pressure Relief by Roof Cutting

To solve the difficulty in controlling floor heave of a retained goaf-side roadway, a new control technique was investigated from the perspective of the pressure relief by roof cutting by combining mechanical analysis, numerical simulation, and engineering tests. The mechanical principle of controlling the floor heave based on pressure relief by roof cutting was attained by analyzing the movement of overlying strata and mechanical characteristics of key blocks before and after the roof cutting. A new technique for controlling the floor heave based on pressure relief by roof cutting was proposed. Research results have shown that after performing pressure relief by roof cutting, the caved gangues in the goaf can support the overlying strata and, thereby, change the movement law thereof and weaken the abutment pressure on the coal wall. Furthermore, the pressure exerted on the roadway floor by the coal wall is lowered to prevent plastic deformation of the floor, thus controlling floor heave in the roadway; a new integrated technique for controlling the floor heave based on pressure relief by roof cutting, flexible yielding, controlling with double-direction-control anchor bolts, and controlling with reinforcing anchor cables is developed, and the technological processes of support, cutting, and protection are summarised. The results of field testing showed that, after applying the new technique, the average floor heave amount of the roadway declines by 64% and the average speed of the floor heave up to 231 m behind the working face decreases by 61%.

A GPR-Based Pavement Density Profiler: Operating Principles and Applications

Density is one of the most important parameters in the construction of asphalt mixtures and pavement engineering. When a mixture is properly designed and compacted, it will contain enough air voids to prevent plastic deformation but will have low enough air void content to prevent water ingress and moisture damage. By mapping asphalt pavement density, areas with air void content outside of the acceptable range can be identified to predict its future life and performance. We describe a new instrument, the pavement density profiler (PDP) that has evolved from many years of making measurements of asphalt pavement properties. This instrument measures the electromagnetic (EM) wave impedance to infer the asphalt pavement density (or air void content) locally and over profiles.

Research on Several Problems in the Characterization of Lightweight Cellular Materials by Low-Impedance Hopkinson Pressure Bar

Abstract There are great challenges in studying the dynamic mechanical behavior of lightweight cellular materials by using the traditional split Hopkinson pressure bar (SHPB) system because of the unique microstructure of such materials. To overcome these challenges, we present in this article a new experimental framework for dynamic loading tests of low-strength cellular materials from the elastic stage to the densification stage. Nylon is utilized as the compression bar in the SHPB system, and its low elastic modulus can cause larger displacement during dynamic loading. Meanwhile, polymethyl methacrylate (PMMA) inserts are attached to the bar end to prevent plastic deformation in that part, and a data correction method is employed to reduce the error caused by inserts. For the problem of wave dispersion during propagation in nylon bars, we use the in situ test method for dispersion correction to obtain more accurate results. We test a closed-cell aluminum foam by this modified SHPB test method and get ideal results. The test results of the aluminum foam show that its mechanical behavior is insensitive to the strain rate at the elastic stage and plastic collapse stage but sensitive to the strain rate at the beginning of the densification stage.

A Novel Lining Method for Eliminating Plastic Deformation and Protrusion of Copper in Cu-TSV Using FEM Analysis

Employing FEM analysis, a new lining method was invented to prevent plastic deformation and protrusion of copper in Cu-TSV after experiencing a thermal cycle (heating up from room temperature to 300°C and then cooling down to room temperature). Using this technique, thermal stresses exerted to the via were reduced to below the yield stress of copper, preventing copper from undergoing plastic deformation. Consequently, not only was the height of copper protrusion at 300°C decreased, but there was no extrusion bulge or dishing at the end of thermal cycle. Compared with traditional titanium barriers, copper protrusion at the end of thermal cycle decreased from 208.2 nm to 3.4 nm after the first thermal cycle and from 325.2 nm to (again) 3.4 nm after 10 successive thermal cycles.

Experimental investigation of an adhesive fracture energy measurement by preventing plastic deformation of substrates in a double cantilever beam test

ABSTRACTA method to prevent substrate damage in a double cantilever beam (DCB) test was experimentally investigated by changing bond-line width. Highly toughened adhesives are developed due to an increase in the demand for structural adhesives. Furthermore, structural materials that are lightweight and excellent in mechanical properties but have limitations in thickness are developed. In contrast, plastic deformation of the substrates is expected when the DCB test is performed with conventional DCB specimens using the aforementioned adhesives and materials. The reduction in the maximum stress on the substrate surface by narrowing a bond-line width is a practical method to prevent plastic deformation when a substrate possesses limited thickness. In this study, the influence of the bond-line width on an adhesive fracture energy in mode I was experimentally investigated by manufacturing DCB specimens in which the bond-line width is narrower than the substrate width. Additionally, the maximum bond-line width to prevent plastic deformation of the substrates was theoretically derived. The evaluated criteria for examining the existence of the plastic deformation by changing the bond-line width exhibited good agreement with the experiment results.

An Experimental Study on the Effect of Surface Texture on Contact Stiffness Using Soft Material

Contact interface is one of the most important factors in a mechanical contact because it is the place where friction, sound, and heat originate. It is therefore inevitable that modeling various phenomenon related to contact dynamics requires a proper representation of the contact interfaces. One of the methods in representing the behavior of two surfaces in contact is by using the parameter of contact stiffness. In this study, the effect of surface texture on contact stiffness is analyzed. the texture was used in order to reduce the randomness of surface roughness. the soft material was chosen to achieve a pure elastic contact thus preventing plastic deformation to the asperities. the analysis was conducted by using an indentation method employing a steel ball with a relatively small indentation force. the result show contact stiffness values of the textured surfaces were smaller than that of smooth surface. This is particularly observed at low normal load at which total deformation of the surface is relatively small compared to the asperities height. This decrease in the contact stiffness value of the textured surfaces can be related to the reduction in the real contact area.

Calculating the Strength of K-H-V Planetary Gears

Рассмотрены вопросы расчета прочности планетарных зубчатых передач вида K-H-V с малой разностью чисел зубьев. При проведении расчетов внесены необходимые коррективы относительно ГОСТ 21354-87 «Передачи зубчатые цилиндрические эвольвентные внешнего зацепления. Расчет на прочность», чтобы использовать его для предупреждения пластического деформирования зубьев при оценке контактной прочности и для предупреждения поломки зубьев при расчете на изгибную выносливость, а также в расчетах на прочность при действии максимальной кратковременной нагрузки. Дополнительно приведен расчет вероятности безотказности работы передачи. На основе выполненных исследований разработана методика расчета планетарных зубчатых передач вида K-H-V на прочность, реализованная в виде интерактивной программы на ЭВМ. Приведены результаты ускоренных ресурсных испытаний передачи, которые были проведены по специально созданной методике и подтвердили основные положения методики расчета на прочность.

Composition, Processing and Properties of Composite Ceramic Sickle Blades from Mesopotamia

ABSTRACTCeramic tools were made in lowland Mesopotamia from about 4500 to 2750 B.C.E. At first hammers, adzes, axes and sickles were made. By about 3300-3100 B.C.E., only sickles were made. We reverse engineered the technology to show that local, salty montmorillonite clay and quartz sand were formed into a composite blade and handle from a biconical coil and fired to 1120-1170°C based on analysis of refiring tests. At 1200°C the montmorillonite clay transforms to glass, so the firing range was right on the edge of slumping the ceramic into a useless mass. To prevent plastic deformation of the clay about 25-33 vol% of quartz sand was added. The extensive glassy matrix phase enabled the best blades to be resharpened by pressure flaking. The compositions, phase assemblage, firing temperature range, material limits on processing, and properties have been characterized for 15 sickle samples from Nippur using Xeroradiography, SEM-EDS, EPMA, and analysis of refiring tests. Strength and hardness tests and toughness calculations were conducted on replicate test tiles made using clay from Pit M at Nippur, Iraq, and sand.Based on finds of small groups of well-fused sickles that were overfired and melted together and our experiments that demonstrated the difficulty of controlling peak temperature range and firing time for the somewhat variable raw material, the sickles probably were fired in small groups, of perhaps 10-15, in small arched, tunnel kilns that achieved high temperatures by facing somewhat predictable oncoming wind flows that provided natural draft. No evidence of workshops has been located, but, based on the archaeological finds at Nippur and our analyses, we propose that sickle-making may have been practiced as a local, seasonal, popular technology with tools being made by farmers or part-time specialists who fired in small, temporary tunnel kilns in fields or near settlements during the dependable seasonal winds. This research investigated the sickles as a well-engineered, but risk-prone ceramic manufacture that fulfilled an important a societal need, agricultural success. The technological choices of craftsmen were narrowed by raw material constraints, risk-taking, practice and workmanship to achieve desired properties and performance characteristics.

Biomechanical Comparison of Acute Hill-Sachs Reduction and Remplissage to Treat Complex Anterior Instability

Objectives:Acute Hill-Sachs (HS) reduction represents a potential alternative method to remplissage for the treatment of an engaging HS lesion. The purpose of this study is to biomechanically compare the stabilizing effects of an acute HS reduction technique and remplissage in a complex instability model.Methods:This was a comparative cadaveric study of 6 shoulders. For the acute HS lesion, a unique model was used to create a 30% defect, compressing the subchondral bone while preserving the articular surface in a more anatomic fashion. In addition, a 15% glenoid defect was made in all specimens. The HS lesion was reduced through a lateral cortical window with a bone tamp, and the subchondral void was filled with Quickset (Arthrex) bone cement to prevent plastic deformation. Five scenarios were tested; intact specimen, bipolar lesion, Bankart repair, remplissage with Bankart repair and HS reduction technique with Bankart repair. Translation, kinematics and dislocation events were recorded.Results:For all 6 specimens no dislocations occurred after either remplissage or the reduction technique. At 90 degrees of abduction and external rotation (ABER), anterior-inferior translation was 11.1 mm (SD 0.9) for the bipolar lesion. This was significantly reduced following both remplissage (5.1±0.7 mm; p<0.001) and HS reduction (4.4 ±0.3 mm; p<0.001). For anterior-inferior translation there was no significant difference in translation between the reduction technique and remplissage (p=0.91). At 90 degrees of ABER, the intact specimens average joint stiffness was 7.0 ±1.0N/mm, which was not significantly different from the remplissage (7.8±0.9 N/mm; p=0.9) and reduction technique (9.1±0.6 N/mm; p=0.50). Compared with an isolated Bankart repair, the average external rotation loss after also performing a remplissage procedure was 4.3 ±3.5 deg (p=0.65), while average ER loss following HS reduction was 1.1 ±3.3 deg (p=0.99). There was no significant difference in external rotation between remplissage and the reduction technique (p=0.83).Conclusion:Similar joint stability was conferred following both procedures, though remplissage had 3.2-degree loss of ER in comparison. While not statistically significant, even slight ER loss may be clinically detrimental in overhead athletes. Overall, the acute reduction technique is a more anatomic alternative to the remplissage procedure with similar ability to prevent dislocation in a biomechanical model, making it a viable treatment option for engaging Hill-Sachs lesions.

Biomechanical Comparison of a Hill-Sachs Reduction Technique and Remplissage: The Potential Benefits of Anatomic Reconstruction

Biomechanical Comparison of a Hill-Sachs Reduction Technique and Remplissage: The Potential Benefits of Anatomic Reconstruction

탄소 표면경화처리 구름베어링의 유효 경화 깊이에 대한 고찰

The effective case depth for case-hardened rolling bearing has been discussed. For this purpose, roll- ing contact fatigue tests for ball bearings built with inner race of various hardness values were conducted until L10 calculating rating life using a bearing life test machine under radial loading. Then, the distribution of residual stress below the inner raceway, which depended on the hardness value, was measured by X-ray diffraction. As a result, the linear relationship was established between the hardness value of the inner race and the theoretical shear stress evaluated at the depth where the residual stress disappeared below the inner raceway. Based on the relationship, it could be found that the factor of safety in bearing manufacturer's rules for the effective case depth of case hardened rolling bearings was set higher. However, it could be also found that the hardness values at the depth where the maximum shearing stress acted below the raceway surface in a tapered roller bearing hardened by the carburizing process, were not sufficient for preventing plastic deformation under the basic dynamic load rating. Consequently, further efforts were still required to reduce or to disperse the contact load on the material design of a rolling bearing in order to prolong its life. Keywordscase hardening (표면경화 ), rolling bearing (구름베어링 ), effective case depth (유효경화깊이 ), hardness (경도), plastic deformation (소성변형)

Testing of pipe sections

Abstract A device and the basic technology has been developed for tensile testing pipe sections samples (tensile testing PSS) for quantitative estimating ultimate tensile and yield stresses in ring samples (PSS samples) cut from pipes. This tensile testing device provides the opportunity for compensating frictional forces during the tensile test, and using exchangeable bearings, the device can be adapted to a wide assortment of pipes. Research has been carried out regarding the shape and size of a stress concentrator introduced into the sample. Relationships have been derived between the shape of the tensile loading curves and the characteristic forces for different types of stress concentrators. It is proposed to use PSS with stress concentrators to prevent plastic deformation in one of the supporting sections (this also allows to correlate the applied forces to one section). The concentrator should be introduced into the tube wall of the sample as a drilled hole. This method is comparatively simple with respect to established testing methods.

An experimental method for studying Young’s modulus of single crystal silicon at high temperature

This article reports a novel indirect experimental method to measure Young’s modulus of single crystal silicon at high temperature. Young’s modulus at high temperature is estimated by measuring the elastic deformation of single crystal silicon microstructure at room temperature and high temperature. Since it is difficult to measure the elastic deformation directly at high temperature, a novel indirect method is presented in this study. In order to prevent plastic deformation at high temperature, the Von Mises yield criterion is applied to predict the onset of plastic deformation. The resulting Young’s modulus of single crystal silicon is about 110 ± 17 GPa at 900 °C in the &lt;100&gt; direction from the present experiment.

Mechanical behavior under cyclic loading of the 18R-6R high-hysteresis martensitic transformation in Cu-Zn-Al alloys with nanoprecipitates

Mechanical damping applications could benefit from the large hysteresis, large pseudoelastic strain and the fact that the transformation stresses of the 18R↔6R martensite–martensite transformation depend very little on temperature in Cu-based alloys. This work presents the 18R↔6R mechanical cycling behavior of CuZnAl shape-memory alloy single crystals with electronic concentration e/a=1.48. A fine distribution of gamma phase nanoprecipitates is introduced to prevent plastic deformation of the 6R phase. Results show that, although significant 6R stabilization is observed at very low frequencies (below 10−2Hz), it is possible to obtain more than 1000 stable pseudoelastic cycles with only minor changes in transformation stresses and hysteresis width at frequencies above 10−1Hz. A more pronounced decrease in transformation stresses is observed after 1000 cycles. Nevertheless, the decrease in hysteresis is small up to 2000 cycles. Reported and present results indicate that pair interchange of atoms can explain the stabilization of 6R under quasistatic experimental conditions. However, at higher frequencies of cycling, stabilization of this martensite shows additional features, leading to a dynamic stabilization with slight effects on the mechanical behavior at the required frequency and number of cycles. On the whole, the behavior of this transformation is unique and very promising.

CAD-model-based Optimal Design of Slide-hinge Spring

AbstractThis research proposes the methodology of using the 3D CAD model of a slide-hinge spring as the basis to analyse the stresses and reaction forces, and implementing Taguchi method to find the optimal parameters of the spring. Firstly, 3D meshes are generated out of the 3D CAD model. In accordance to the mechanism characteristics of the slide hinge, primary data for engineering analysis are determined, including mesh properties, material properties, boundary conditions, contact definitions, and iterative procedure. MARC, a well-known CAE software, is then used to find von Mises stresses and reaction forces of the spring during its movement in a slide hinge. In order to prevent plastic deformation and damage of the spring, the Taguchi method is adopted in this paper to reduce the maximum stress during spring movement. All details of optimizing the dimensional parameters of the spring will be discussed in the paper, including the determination of control factors and their levels, setup of orthogonal a...