Liner Interface Research Articles

Study on the Bearing Capacity of the Polyethylene Pipe–Cured-In-Place Pipe Liner Composite Structure under External Pressure

Cured-in-place pipe (CIPP) technology is used to repair deformed municipal polyethylene (PE) pipes caused by design flaws, construction issues, or external loads. However, research on CIPP for PE pipes is limited, restricting its broader application. This research focuses on the mechanical response characteristics and failure modes of the composite PE pipe–CIPP liner structure under external loads. Using experimental setups involving comparative test groups with different diameters and wall thickness ratios (DR values, defined as the ratio of the pipe’s outer diameter to its wall thickness), this study evaluates the effects of the liner’s elastic modulus, the bonding effectiveness at the PE pipe–CIPP liner interface, and the initial ovality of the pipes on the load-bearing capacity. The experimental results reveal that CIPP liners substantially enhance the stiffness and load-bearing capacity of PE pipes, with improvements ranging from 200% to nearly 500% depending on the pipe’s DR value. A novel ring stiffness prediction model is also introduced and validated against the experimental data. This model provides a theoretical framework for understanding the complex interactions at the PE pipe–CIPP liner interface and aids in designing more resilient urban drainage systems.

Inspection of Liner Wall Thinning and Interface Debonding in Bimetallic Lined Pipes Using Pulsed Eddy Current Testing.

Bimetallic lined pipe (BLP) has been increasingly used in offshore and subsea oil and gas structures, but how to identify the invisible inner defects such as liner wall thinning and interface debonding is a challenge for future development. A nondestructive testing (NDT) method based on pulsed eddy current testing (PECT) has been proposed to face these difficulties. The inspection of the BLP specimen (AISI1020 base tube and SS304 liner) is implemented from outside of the pipe by using a transmitter-receiver-type PECT probe consisting of two induction coils. By simplifying the BLP specimen to stratified conductive plates, the electromagnetic field interaction between the PECT probe and specimen is analytically modeled, and the probe inspection signals due to liner wall thinning and interface debonding are calculated. In order to highlight the weak response (in microvolts) from the liner, the inspection signals are subtracted by the signal, which is calculated in the case of only having a base tube, yielding differential PECT signals. The peak voltage of the differential signal is selected to characterize the liner wall thinning and interface debonding due to its distinguishable and linear variation. Experiment verification is also carried out on a double-walled specimen simulated by a combination of a Q235 casing pipe and SS304 tubes of different sizes. The experimental results basically agree with the analytical predictions. The peak value of the PECT signal has an ascending and descending variation with the increase in the remaining liner wall thickness and debonding gap, respectively, while the negative peak value shows opposite changes. The peak value exhibits a larger sensitivity than the negative peak value. The proposed method shows potential promise in practical applications for the evaluation of the inner defects in BLP lines.

GCL-LLDPE geomembrane interface friction angle evaluation and stability analysis of a valley fill leach pad project

The Los Chancas mining project, initiated in 1998, is a copper mine focused on extracting copper sulfides and oxides. In 2020, a mine plan update required a review of the constructability design and an evaluation of the Permanent Leach Pad and Filtered Waste/Rock Dump's physical stability. This paper presents results from an evaluation study regarding friction angles at the liner interface and stability analysis in the VLF pad. Previously, an internal friction angle of 23° was established for the basal liner interface (LLDPE-GCL) to meet stability requirements. However, due to the high required friction angle, the pad design was updated with lower slopes. The study evaluated various GCL materials from two suppliers using direct shear tests, revealing that the GCL from the second supplier achieved a high friction angle of 22.3° at the interface. Stability analysis considered two critical sections, examining three types of failure under both static and pseudo-static conditions. Results showed a need for a minimum friction angle of 16° in static conditions and 20.5° in pseudo-static conditions to ensure compliance. These results suggest the potential use of high strength geosynthetic materials in the studied areas, with a preference for the GCL material offering the highest friction angle.

Structure and strain state of aluminum bars at the initial phase of extrusion

The structure of insufficiently deformed areas at the non-steady phase of extrusion was studied. The tests at Kamensk Uralsky Metallurgical Works using a 120 MN press and 800 mm dia. container, in order to extrude a 355.6 mm dia. Bar was performed. The bar material is the Al–Mg–Si AD33 aluminum alloy (GOST 4784), similar to ASTM 6061. The percentage reduction was 80 %, and the reduction ratio was 5.06. After that, the macrostructure, microstructure, and average grain size along the radius, mechanical properties at room and elevated temperatures were investigated. It was found that the extruded bar macrostructure is fine-grained, homogeneous, and dense, with no nonmetallic or intermetallic inclusions. The cross-section contained several structures. The central part is weakly deformed preserving the dendritic cell structure inherited from the casting. At the circumference, a streaked structure is formed. Its components are crushed and uniformly distributed. We measured the strength at elevated temperatures and compared the results to the data available in the literature. The tested material strength almost doubled, thus indicating its incomplete softening. The ductility was also performed. The DEFORM-2D software, in order to simulate the low reduction of extrusion was used. The metal at the circumference is exposed to a greater strain from the extrusion beginning. A step-by-step analysis indicated that at the first step, the strain is localized near the die hole. In the second step, a rigid area is formed in the vicinity of the die/container liner interface. The circumference layer of metal with a 1.75–2.00 reduction of area is formed. At the bar center, this range is 0.75–1.00 (half of the circumference value). In the third step, the circumference layer with an elevated strain has a wedge-like shape. In the fourth step, the circumference layer (with elevated strain) has an equal thickness along the extrusion axis. This indicates the steady phase. The plastic strain at the bar front end is higher at the circumference than in the center. This confirms the structural analysis results. They show that the central part of the bar may retain its cast structure, while the circumference is deformed. If the bar central part is required to have some specific properties, the bar has to undergo another manufacturing operation to increase the accumulated strain. Re-extrusion processes the areas insufficiently deformed during the first extrusion.

エンジン要素の熱的な摩擦特性に関する研究 - ピストンリング・シリンダライナの混合・境界潤滑

Similar to vehicle engines, marine engines are required to realize zero emissions of poisonous gas like SOx and GHG like CO2. Therefore, fuels used for future engines will be needed to reduce the content of sulfur and carbon. Under such requirements, the lubricated sliding interface of a piston ring and a cylinder liner often suffers damage, such as excessive wear and scuffing failure, caused by changes in lubrication condition due to in-cylinder combustion and/or fuel-derived substances mixed in the lubricating oil. Given this, appropriate measures are eagerly required to prevent such damage. The thermal friction characteristics of the ring / liner interface under the mixed / boundary lubrication regime during engine break-in procedure are thought to be almost the same as those of cam / tappet under the boundary lubrication regime when using low-viscosity lubricating oil with additives, which was the key subject the authors investigated in their previous study. By analyzing changes in frictional shear stress and the surface temperature and examining a correlation between them, just like the Arrhenius’ equation, it has been clarified that the temperature of the interface displays lubrication functions that can reduce friction, wear and scuffing. Concerning the viscosity and additives of the lubricating oil, the surface roughness of the interface, the ring profile, the contact pressure and the sliding velocity the authors have also investigated how the surface temperature contributed to reducing friction. To this aim, they analyzed the ring / liner data measured with a rotary disk type reciprocating friction test apparatus, which makes it possible to detect the friction force and the ring temperature under the same contact pressure and sliding velocity as those during engine break-in procedure.

Seismic analysis of landfill using advanced numerical approach considering material and contact nonlinearity

Seismic stability is of vital importance for municipal solid waste (MSW) landfills and this study proposes an advanced numerical approach considering material and contact nonlinearity for seismic analysis of landfill. The MSW is modeled as porous media through the u-p formulation and the bounding surface plasticity model based on the double-phase assumption is adopted. The dynamic friction model is applied to define the interface shear behavior so that the elastoplasticity and displacement-softening property of the liner interface can be well reflected. The advanced numerical method is validated through back analyses of soil column tests and centrifuge tests of landfills. The subsequent site-specific case study indicate that earthquake-induced sliding along the liner system is a typical failure mode of canyon landfill and the stability can be assessed based on the permanent displacement, which can also be roughly estimated with simplified semiempirical models by setting the yield coefficient as the residual friction coefficient of the liner interface.

A limit equilibrium approach to the use of stability bunds in the design of HDPE-lined tailings storage facilities

In recent years the requirements for a barrier system between the waste body of tailings storage facilities (TSFs) and the natural ground (NG) has necessitated the use of HDPE-lined TSFs in South Africa and other countries. The addition of an HDPE liner creates an interface between, inter alia, the tailings and surrounding soils on the footprint of the TSF. It is known that low-strength materials beneath slopes can cause slope instability. One method which can theoretically mitigate this instability of a lined TSF is the addition of stability bunds along the footprint of the TSF. Altering the profile of the footprint to include slope changes which oppose the direction of the failure creates passive slices in a limit equilibrium analysis. The passive slices actively oppose the movement of active slices, resisting the mobilization of tailings, thus greater active slice forces are required to develop a failure surface running along the liner interface. Two scenarios are presented and compared. The first scenario retains the ground profile unaltered and the second scenario includes stability bunds along the ground profile. An in-depth assessment is made of the interslice forces and the interface shear stresses for each scenario. The theoretical background is discussed in greater detail to determine the mechanisms of reinforcement provided by the bunds.

Dry and Wet Lubrication Analysis for Multi-Material Hip Assembly

Hip joint repair/replacement is one of the most thriving orthopedic surgical procedures in the human body. The group of patients undergoing hip replacement considerably includes young and physically active persons with varying movements thus requiring longer product life and ease of maintenance. Perfect lubrication in hip assembly ensures a low wear rate and better product life. The present work focuses on dry and wet lubrication analysis of complete implant assembly instead of an individual part. The assembly consists of a stem, head, liner and cup, each made of different materials like a ceramic femoral head mounted over a metallic femoral stem with a polyethylene liner and a metallic acetabular cup. In this work, eight metal-materials are considered for stem/cup, three ceramic materials for the head and two polyethylene materials for the liner. The combinations of these materials are evaluated for various mechanical parameters. Dry (µ = 0.13) and wet (µ = 0.05) lubricating conditions between the liner and femoral head have been considered and their effects on the head, liner and cup have been evaluated for the optimization of Hip joint design. Fifty percent of re-surgery cases arise because of excessive wear out resulting in aseptic loosening of the femoral head and liner interface. Femoral head of size 28 mm diameter with 2 mm thick liner and 3 mm thick acetabular cup are modeled and are analyzed for axial pay load of 2.3 kN. The maximum von mises stress and total deformation for various material combinations of implant assembly have been compared to select the most suitable one for the arthroplasty implantation. The combination of CoCrMo – Ceramics – HXLPE – CoCrMo demonstrates minimum stress and deformation for all three parts i.e. femoral head, liner and acetabular cup under present loading and boundary conditions. ZTA is emerged as the preferred ceramic material for femoral head having a higher compressive strength.

Combined effects of elastic deformation and piezo-viscous dependency on the performance of a journal bearing operating with a non-Newtonian fluid

A theoretical study of the effects of elastic deformation and the variation of viscosity with pressure on the performance characteristics of a circular journal bearing lubricated with non-Newtonian fluids. The Barus law and the power law model are used to express the viscosity-pressure variation and the non-Newtonian behavior of fluids respectively. To determine the displacement field at the fluid film bearing liner interface, the elastic thin liner model is used. The modified Reynolds equation accounting the viscosity pressure dependency in the non-Newtonian fluids is mathematically derived and solved using finite difference method, to obtain the fluid film pressure field. The static performance characteristics for finite-width journal bearing are evaluated for various values of pressure-viscosity coefficient, the power law index n, and the elastic deformation coefficient. According to the results obtained, it is found that the hydrodynamic pressure and non-dimensional load-carrying capacity increase as the power law index and pressure-viscosity coefficient increases especially for rigid and heavily loaded bearing case. In addition, the combined effects of the elastic deformation and the viscosity pressure dependency are found to be more pronounced on the performance characteristics of a heavily loaded journal bearing operating with a shear-thickening fluid.

Thermophysical and tribological behaviors of multiwalled carbon nanotubes used as nanolubricant additives

This study investigates the thermophysical and tribological characteristics of engine oil (SAE 10W-40) using multiwalled carbon nanotubes (MWCNTs) as nanolubricant additives. The MWCNT additives based nanolubricant were formulated using an ultrasonic probe. The tribological performances of MWCNTs nanolubricant were evaluated by a reciprocating platform that simulated the piston ring and cylinder liner interface under various circumstances (i.e., contact loads and sliding velocity). The thermophysical performances of MWCNTs nanolubricant were evaluated using ultraviolet-visible spectrometry, Brookfield viscometers, a thermal conductivity meter, and thermogravimetric analysis. Furthermore, the wear mechanisms of the frictional surfaces were supported by field emission scanning electron microscopy and energy dispersive spectrometer. Critically, the flow characteristics of MWCNTs nanolubricant samples displayed non-Newtonian (shear-thinning) behavior, but the behavior of SAE 10W-40 oil was similar to Newtonian fluids. The friction coefficient decreased by 4%–34% and 26%–32% at different loads and speeds. Moreover, the specific wear rate of the ring and liner surfaces decreased by 29% and 40%, respectively, at 240 N load and 0.33 m s−1 velocity after a sliding distance of 22.57 km. These results suggest that MWCNT additives based nanolubricant effectively lubricated the mechanical applications.

Friction at Ring–Liner Interface Analyzed with a Systematic Surface Characterization

The ring–liner interface of an internal combustion engine is a very important interface because its behavior directly affects fuel efficiency of an automobile and the engine life. The liner surface is complicated, with honing features on top of the primary roughness. Moreover, liner surfaces considered here also contain pores that are random in terms of their shape and distribution. The work reported in this article systematically models the tribological performance of such surfaces in a ring–liner interface. A microscopic single-pore computational fluid dynamics analysis is conducted on the representative pore shape obtained from liner–surface characterization to quantify the effect of pores on friction. A pore influence zone is suggested, and a friction reduction factor is defined for pores. A macroscopic ring–liner interface model is developed in parallel to solve the average Reynolds equation for a representative section with the consideration of the starvation and cavitation effects. The two models are then combined to predict friction at the ring–liner interface for the liner surfaces with pores. Excellent agreement is observed between our modeling and experimental results. The effects of random pores of varying densities in the range of 2–10% on the ring–liner interface performance are studied under flooded and starved conditions. The results indicate that surface pores increase friction when the ring–liner set is operated under flooded conditions. However, when starvation occurs, surface pores help reduce friction.

Special Issue on Tribology of Additive Manufacturing

Special Issue on Tribology of Additive Manufacturing

Fabrication and Testing of Bioinspired Surface Designs for Friction Reduction at the Piston Ring and Liner Interface

Abstract The piston ring and liner interface is a major source of friction loss in automotive combustion engines. This loss can be mitigated by learning from surfaces from nature that manipulate friction. In this study, novel fabrication and testing methods were developed and used to efficiently compare three-dimensional bioinspired surface designs to existing piston liner surface topographies. Surface designs inspired by frog toes were fabricated using two-photon lithography, and their frictional performance is compared to that of typical piston liner topography. These designs reduce surface friction by an average of 18%, and up to 39%, compared to a flat control. The developed fabrication and testing methods allow comparison with existing topographies without needing to transfer the designs to the original materials and provide an efficient approach for designing surfaces to meet the frictional challenges of the future.

Temperature Effects on Stability and Integrity of Geomembrane–Geotextile Interface in Municipal Solid Waste Landfill

Review of the limited experimental studies available in the published literature that investigate the effects of temperature on the shear strength of typical geomembrane (GM) and geotextile (GTX) interface is performed. These studies suggest that the shear strength of GM–GTX interfaces generally increase with an increase in temperature. However, there is no study that examined the combined effect of the temperatures along the bottom liner and the large displacement induced by the waste settlement on the short-term and long-term stability and integrity of the GM–GTX interface in a composite bottom liner system in municipal solid waste (MSW) landfills. This paper presents the application of a thermal model to predict the evolution and distribution of temperatures within the waste and along the bottom liner system of a typical landfill cell model, while simultaneously evaluating the influence of the predicted temperatures on the shear response of GM–GTX interfaces in the composite bottom liner system. The predicted temperatures along the liner interface of the simulated landfill cell varied between 4 and 32 °C, which are well within the reported temperatures in and around the bottom liners in MSW landfills. The results also suggest that beginning the placement of waste in summer is favorable than in winter, since the high temperatures at the GM–GTX during summer mobilize higher shear strengths resulting in lower shear displacements. Further, if stability analysis using limit equilibrium method is performed, then the shear strength of GM–GTX interface corresponding to the low temperature ranges expected at the site should be used for conservative and reliable estimates of the stability of the bottom liner system.

Dynamic shear behavior of GMB/CCL interface under cyclic loading

The dynamic shear behavior of composite liner interface is of great importance for landfill seismic analysis. In this study, an experimental investigation of the shear behavior of the interface between smooth high density polyethylene (HDPE) geomembrane (GMB) and compacted clay liner (CCL) is presented. A series of displacement-controlled cyclic shear tests were conducted to investigate the effects of displacement amplitudes, normal stress levels and number of cycles on the GMB/CCL interface shear behavior. Cyclic loading with higher displacement amplitude will produce greater vertical contraction and lower interface initial shear stiffness. Also, significant shear strength degradation was observed within the first 5 shearing cycles, then followed by slight interface reinforcement in subsequent cycles. The dynamic shear modulus of GMB/CCL interface is dependent on both normal stress levels and displacement amplitudes, while the damping ratio is only affected by displacement amplitudes. Finally, a method considering the GMB/CCL composite liner as an equivalent soil layer was proposed, which is useful for landfill seismic analysis.

A Study of the detonation wave shape inside confined explosive with a metallic copper liner

The behaviour of shock wave inside a shaped charge is so important that the detonation wave nature characterizes (determines) the degree of jet coherency at the liner interface. The detonation wave shape inside the shaped charge depends on the casing thickness, material, the liner material, geometry and the applied wave shaper geometry. In this paper, a series of numerical simulation models were performed to study the incident and reflected waves and to characterize the resulting shock wave front to evaluate its effect on the produced (generated) jet characteristics. The used code was Autodyn 3D based on non-linear dynamic analysis with jetting analysis model. Inert wave shapers (Lead, Aluminium and steel) and active ones (TNT and PETN) behaviour were studied. The liner type used in this study was copper with in which the apex angle of the liner cone was 40°. It was concluded that the wave front shape has an obvious influence on the characteristics of the jet formation and its properties such as mass of jet and velocities of its tip. Also, the bulk sound speed of the liner itself in addition to the collapse characteristics of the liner was discussed in this paper successfully.

Field-Testing of Biodiesel (B100) and Diesel-Fueled Vehicles: Part 4—Piston Rating, and Fuel Injection Equipment Issues

AbstractThis study investigated the use of biodiesel (B100) and baseline diesel in two identical unmodified vehicles to realistically assess different aspects of biodiesel's compatibility with modern common rail direct injection (CRDI) fuel injection equipment (FIE) and evaluate biodiesel's long-term durability/compatibility with engine components. Two identical vehicles were fueled with biodiesel (B100) and baseline mineral diesel for 30,000 km field-trials on highway under identical operating conditions. Exhaustive experimental results from this series of tests are divided into four segments. The fourth and the last paper of this series compares the effects of long-term usage of biodiesel on piston deposits and FIE components compared to baseline mineral diesel. A key challenge for improving engine performance and fuel economy is the reduction of frictional losses, primarily at the piston ring–liner interface, which accounts for majority of frictional losses. Piston rating was done for the two vehicles after the conclusion of field-trials and it revealed that rating of different piston sections was ∼5–15% superior in case of biodiesel-fueled vehicle compared to that of diesel-fueled vehicle. Performance of FIE components such as fuel filter, fuel injectors, and fuel pump was assessed after the conclusion of field-trials. Pressure drop at different fuel flow-rates across the fuel filter was measured for assessing the fuel filter blockage. Pressure drop across biodiesel filter was ∼30% higher than diesel filter after 10,000 km usage but almost twice after 15,000 km usage. These experimental results indicated that some additional technical measures should be taken by automotive manufacturers to offset these technical challenges before biodiesel is adapted on a large-scale in modern CRDI vehicles.

Shear strength of landfill liner interface in the case of varying normal stress

Landfills are sequentially filled by solid waste lifts, thus normal stress on the liner interface changes in different shear stages, which may affect selection of interface strength in landfill slope stability analysis. Shear tests were conducted at the liner interfaces of geomembrane/geotextile (GM/GT) and geomembrane/geocomposite/sand (GM/GC/Sand), and the normal stress changed in different shear stages. Values of friction angles on both the GM/GT and GM/GC/Sand interfaces obtained by direct and simple shear tests under increasing normal stress in the hardening, softening, and large-displacement stages were lower than those obtained by the traditional direct shear test. The reduction was greater for peak friction angles. Since the peak liner interface strength obtained by staged loading is lower than the peak interface strength by using the traditional shear test method, using the peak shear strength obtained from the traditional direct shear test for the base floor liner to conduct slope stability analysis may cause an un-conservative result. It is necessary to consider the effects of normal stress changes on the liner interface strength in landfill slope stability analysis.

A novel UV-curing liner for NEPE propellant: Insight from molecular simulations

In this paper, a new simulation strategy was proposed for constructing the UV-curing crosslinking model by using computational programming. Based on this algorithm, the UV curing model of polyurethane acrylate (PUA) liner was effectively built at a molecular scale. Molecular dynamics (MD) simulations were first conducted to estimate the mechanical properties and thermal transition behavior, and the simulated results were a good agreement with the experimentally measured values. Then, the solubility parameters and radial distribution function (RDF) were calculated to get an in-depth understanding of the interface interaction between the liner and other components. Finally, we calculated the diffusion coefficient of nitrate plasticizer molecules in the liner and explored the influencing factors. The dynamic behavior of the nitrate plasticizer in the liner interface was also investigated, and the results demonstrated that PUA liner could effectively prevent the migration of plasticizer because of the higher crosslink density. These researches help us deeply understand the structure-property correlation and provide molecular insight into the mechanisms of nitrate plasticizer migration, which was useful for the structure design and material selection of NEPE propellant liner.

Addressing Antibiotic Hip Spacer Instability via Hybrid Screw-cement Fixation of a Constrained Liner and Cement-rebar Interface Techniques: A Technical Narrative.

Prosthetic joint infection is a challenging and devastating complication after total hip arthroplasty. The benchmark for treatment remains two-stage revision arthroplasty, in which an antibiotic-impregnated spacer is used to eradicate the infection. Although several types of spacer constructs have been described, they have historically been associated with high rates of mechanical complications, namely, dislocation, spacer fracture, and periprosthetic femur fracture. Spacer dislocation is the most common, with reported rates as high as 41%. Here, the authors present a surgical technique to improve the mechanical stability of an articulating hip spacer via a hybrid screw-cement fixation technique that allows for joint motion and weight bearing during the treatment period while minimizing the risk of mechanical failure. An additional technique is described to address acetabular bone loss, which has been associated with a higher spacer dislocation rate, through a cement-rebar interface construct.