Thin Liner Research Articles

Analytical expressions for stress distributions in lined pipes: Axial stress and contact pressure interaction

Lined pipes are Carbon Manganese pipes (backing steel) with a thin liner of corrosion resistant alloy, mechanically bonded to the backing steel. Lined pipes are cheap to produce compared to clad pipes, where the liner is metallurgically bonded to the backing steel, but they are also more complex to design for. One particularly challenging aspect is to determine load/displacement levels for potential disbondment between the liner and the backing steel. In that context, the strength of the metallurgical bond between the backing steel and the liner in a lined pipe may have an important influence. The metallurgical bond may be characterized by residual stresses in the liner and the friction coefficient between the inner surface of the backing steel and the outer surface of the liner. Current industry testing practice to determine the magnitude of residual stresses is defined in API 5LD, but these tests fail to consider boundary effects and Poisson’s ratio effects which have a substantial impact on the measured stress levels. An analytical formulation for stress levels in the liner close to free boundaries, and interaction between axial and hoop stresses are presented in this paper and validated by detailed finite element analyses. This formulation provides excellent transparency in terms of understanding which physical parameters are important in the surface interaction between the liner and the backing steel, and, among several applications, they are a highly useful tool to reinterpret the test regimes suggested in API 5LD.

Fracture mechanics interpretation of thin spray-on liner adhesion tests

Thin spray-on liners (TSLs) are relatively thin (2–5mm) fast setting liner materials that are sprayed onto rock surfaces to support mining excavations. The adhesive strength between a TSL and a rock surface is an important property controlling the design and performance of TSL rock support systems. In this study, direct pull-off TSL adhesion tests were interpreted based on a fracture mechanics approach. An edge crack propagation equation for a generic case (ν≠0.5) was derived and the failure modes of TSLs were studied. It was found that the current TSL adhesion test sample geometries show confined behaviour, the failure mode of the tests are edge crack propagation. Bulk cavitation of TSLs can only occur for very compliant samples (E<0.6MPa). Adhesion tests done on a TSL product, Tekflex, applied on concrete substrates were examined to verify the edge crack propagation.

Comparison of five approaches to keeping power line maintainers’ hands warm during work in the cold

Electric utility workers in Canada must frequently work in the cold and must wear thick rubber gloves which can result in rapid fatigue and reduced performance. The purpose of the study was therefore to document the challenge of working in the cold wearing the standard five-finger rubber gloves and covers and compare them to two equipment options, mitten style gloves or a prototype wool liner, and two heating options, glove or torso heating. The dependent measures were grip force, temperature, dexterity (modified Purdue pegboard test and a simulated occupational task), finger sensitivity (Von Frey hair test), perceived effort and thermal sensation. The study population consisted of 10 experienced male utility workers. They worked in a controlled temperature walk-in chamber (-20 degrees Celsius) and performed simulated utility work for 45 minutes with interspersed test batteries. The mitten style glove and woolen liner in a standard glove reduced the effects of working in the cold compared to the standard five-fingered variety with a thin cotton liner. We found that the mitten style glove showed lesser drops in skin temperature for the 3rd and 5th digits than the other conditions (p < 0.05).

Evaluation of modeling techniques for a type III hydrogen pressure vessel (70 MPa) made of an aluminum liner and a thick carbon/epoxy composite for fuel cell vehicles

Stress distributions in the composite layers of a Type III hydrogen pressure vessel composed of a thin aluminum liner (5 mm) and a thick composite laminate (45 mm) were calculated by using three different modeling techniques. The results were analyzed and compared with the plausible stress distribution calculated by a full ply-based modeling technique. A laminate-based modeling technique underestimated the generated stresses especially at the border between the cylinder and dome parts. A hybrid modeling technique combining a laminate-based modeling for the dome part with a ply-based modeling for the cylinder part was also tried, but it overestimated the generated stresses at the border. In order for the ply-based modeling technique to carry out precise analysis, a fiber trajectory function for the dome part was derived and the composite thickness variation was also considered.

Design of Pressure Relief Valves for Protection of Steel-Lined Pressure Shafts and Tunnels Against Buckling During Emptying

Using high-strength steels for pressure shafts and tunnel liners and taking into account significant rock mass participation allows the design of comparatively thin steel liners in hydropower projects. Nevertheless, during emptying of waterways, these steel linings may be endangered by buckling. Compared with traditional measures such as increased steel liner thickness and stiffeners, pressure relief valves are a very economical solution for protection of steel liners against critical external pressure and therefore buckling during emptying. A calculation procedure has been developed for the design of the required number and arrangement of pressure relief valves, and this has been used successfully in practice. Systematic model tests enabled the assumptions of the design method to be verified.

Local Buckling of Tight Fit Liner Pipe

Abstract A promising possibility to reduce costs in pipelines that require corrosion resistant alloys (CRAs) is the use of lined pipe, consisting of a carbon steel outer pipe and a CRA liner pipe. Research has been carried out into the local buckling behavior of the thin walled liner pipe. Important parameters are the wall thickness and material properties of the liner pipe, the contact force between the liner pipe and the outer wall, the coefficient of friction between the two walls, and the imperfections. Local buckling of the liner pipe due to combinations of bending and normal force is one of the failure modes to be considered in offshore installation of line pipe. The results of axial compression tests are presented: on liner pipe only (I), on liner pipe while positioned in the outer pipe (II), and on the joined liner and outer pipe (III). Thanks to the support of the outer pipe, local buckling of the liner pipe occurs at much higher stresses and strains than without that support. The measured buckling strains of the tests on liner pipe only (I) are in reasonable agreement with local buckling equations. Finite element calculation results are presented and compared with test results. The influence of the determining parameters for the different load cases is discussed.

パラダイムシフト 20 : 半導体デバイスのトレンド(基調講演,OS16 東京ブロック・山梨ブロック共同企画 機械工学が支援する微細加工技術(半導体・MEMS・NEMS)1(半導体・MEMS・NEMS),オーガナイズド・セッション)

Although semiconductor device has been developed by design rule scaling and wafer size enlarging, there are still many difficult challenges such as new material introduction, 3D integration etc. Problems and developments in 45nm device are introduced herein as Paradigm Shift 45. Now is the time to challenge 20nm devices. There are many new challenges in 20nm device such as thin and conformal liner integration. Etc. Those problems are introduced as Paradigm Shift 20.

Elastic stability analysis of loosely fitted thin liners – A proposed simplified procedure and evaluation of existing solutions

The paper reports the results of an extensive numerical simulation to estimate the elastic buckling pressure and the corresponding thrust and bending moment induced in loosely fitted thin liners. The study is conducted numerically using a two-dimensional (2D) non-linear finite element model that accounts for the effects of large deformations on the stability of loosely fitted liners. The finite element results together with a non-linear multi-variant regression analysis are used to develop simplified non-dimensional formulae that provide the critical pressure, thrust and bending moments, at buckling, based on the liner’s geometry and material properties. In addition, several other analytical and numerical solutions for the same problem are revisited and critically reviewed. For comparison purposes, two of such methods are extended to allow for the calculation of the thrust and bending moment developed at the most heavily stressed point in the loosely fitted liners at the onset of buckling. In general, the comparison reveals the appropriateness of the proposed regression models in predicting the critical pressure and the associated thrust and bending moment induced in imperfect loosely fitted liners. Developed formulae provide designers with a simple and reliable means for ensuring stability and safety of such special type of structures.

Deformation of metal-backed acetabular components and the impact of liner thickness in a cadaveric model

Shell deformation of resurfacing and all-metal modular cups following press-fit implantation has been reported, but not for conventional metal-backed cups with polyethylene liners. The deformation of acetabular components with historical and thin polyethylene inserts after press-fit insertion was evaluated using a cadaveric model. All shells and liners deformed upon implantation. Following joint loading, shell pinch decreased from 0.32 to 0.22 mm (p = 0.019) and from 0.29 to 0.13 mm (p = 0.003) for the thin and thick liner groups, respectively. Liner pinch also decreased from 0.17 to 0.04 mm (p = 0.031) and from 0.06 to 0 mm (p = 0.103) for the thin and thick liner groups, respectively. There were no significant differences between the thin and thick liners. Liner deformation was influenced by the initial shell deformation and donor bone quality. Shell and liner pinch decreased following joint loading, suggesting a settling in effect.

Polyethylene in total hip arthroplasty: half a century in the limelight

Polyethylene in total hip arthroplasty: half a century in the limelight

Routine Surveillance of Modular PFC TKA Shows Increasing Failures after 10 Years

A 10-year survivorship of 100% was reported for patients with PFC cruciate-retaining prostheses. Beyond 10 years, we observed additional polyethylene wear likely related to thin liners gamma-irradiated in air and were concerned this wear might predispose to implant construct failure. We therefore determined (1) the functional scores at a minimum of 15 years followup, (2) rates of radiographic failure, (3) overall revision rates, and (4) mode of failure after 10 years and the fate of the revised implants. We retrospectively reviewed 75 patients with 101 press-fit condylar posterior cruciate-retaining prostheses. At a minimum followup of 15 years, 35 patients (47 knees) were living and evaluated clinically. No patients were lost to followup. There were no revisions during the first 11 years and six reoperations subsequently were performed in five patients (6% overall rate of revision but 12.8% in patients who survived more than 15 years). Three of six revisions had concerning liner wear at 10 years and all six were revised for polyethylene wear. Polyethylene exchange was performed in four of the five patients who underwent revisions, all of whom were doing well at an average of 7.2 years (range, 4.7-9.1 years) after the revision procedure. At long-term followup, the overall revision rate remained low (6%). For patients surviving 15 years or more, the rate of revision was 12.8% and all revisions were secondary to aseptic sequelae of polyethylene wear. All revisions occurred more than 10 years after the initial procedures. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Ultrathin DPN STI SiON liner for 40nm low-power CMOS technology

At sub-40 nm CMOS technology nodes, the implementation of shallow trench isolation (STI) becomes more challenging due to shrinking geometries and stricter device leakage requirements. As device geometries are shrinking, STI liner is also becoming thinner and plays an important role for the minimal consumption of device active area while effectively rounding the STI corner and minimizing stress-induced defects. Consequently, STI stress is enhanced by the scaling of STI-pitch, the volume expansion induced by STI liner and film stress of filling materials. This paper discusses the benefits of SiON liner growth by decoupled-plasma-nitridation (DPN) and SiON liner induced stress compared to conventional pure oxide liner growth by in situ steam generation (ISSG). Thin STI SiON liner offers lower sub-threshold leakage current without drive current loss for transistor performance. Moreover, junction leakage current is also reduced with scaling device active area. Thus, better device performance results in better minimum operation voltage (Vcc_min) of low-power 6T-SRAM. This paper demonstrates the influences of thin STI SiON liner growth by DPN in STI manufacture.

Letter to the Editor: THA with the ABG I Prosthesis at 15 Years: Excellent Survival with Minimal Osteolysis

To the Editor: I read the paper by Baker et al. [1] with great interest. The authors reported high survival with minimal osteolysis using the ABG-1 prosthesis in total hip arthroplasties (THA). Their 15-year survival rates of the acetabular and femoral components were 86.9% and 98.6%, respectively, and they concluded that the ABG-1 prosthesis continues to show excellent long-term results. Unfortunately, I cannot confirm these positive findings for the ABG-1 prosthesis, especially regarding the cup. Poor survival of ABG-1 prostheses implanted from 1994 to 1995 was observed, with periprosthetic osteolysis and aseptic cup loosening being leading reasons for revision [7]. The overall 12-year cumulative survival was 0.55 (95% CI, 0.443–0.659), which is much poorer than the survival reported by Baker et al. This also disagrees with reports from other centers [2, 4, 5, 10]. The Swedish hip arthroplasty register’s annual 2007 report [13] found an increased risk of revision with ABG-1 cups (1.28 [95% CI, 1.06–1.54], Cox regression). Similarly, the 10-year survivorship was 80.5% ± 4.5%. In contrast, several studies [3, 9, 12] report data consistent with that provided by Baker et al.; therefore, I think the issue deserves careful comment. Baker et al. reported the experience of one center and a single-surgeon patient group, which could point toward patient selection and surgical factors that could favor these patients over those receiving surgery performed by several surgeons at several different centers. However, the findings of Herrera et al., in a multicenter study of the ABG-1 prosthesis [9], are consistent with those of Baker et al., suggesting that this variable may not play an important role. Baker et al. did not report on variables that could influence implant survivorship such as primary diagnosis or cup size. The latter is closely associated with a risk of premature failure, especially in cementless THA, as it determines the thickness of the polyethylene (PE) liner. In earlier studies [6, 7], a thin PE liner increased the risk of premature failure, and patients with a cup < 50 mm (ie, with 5.9 mm maximal PE thickness) had an odds ratio and relative risk for revision of 4.278 and 2.135, respectively. Given these findings one wonders whether the patients in the study by Baker et al. could have received larger cups and thus achieved better survivorship because of this. Presuming selected patients, their conclusions may not be generalizable to a broader ABG-1-patient group and the readers should take selection into consideration. Baker et al. stated they observed no “high volumes of osteolysis” in their patients, regardless of revision. The reason might lie in a possible role of resistance to osteolysis development in their patients compared with those of Gallo et al. [8] and of others [11, 14]. Readers and authors of any study of the ABG-1 prosthesis should consider the contradictory data regarding survivorship, increased risk of revision, PE wear rate, and osteolysis until the reasons for these discrepancies can be explained. The article by Baker et al. should be read with caution and patients with ABG-1 prostheses should be closely monitored.

The Applicability of GRP and NRP Composites in Rehabilitation of Unpressurized Pipes

Glass fiber reinforced polymer (GRP) and needle reinforced polymer (NRP) composites have been used to produce a new kind of thin cross section liner for rehabilitation of in ground sewer pipes. The liner made from resin impregnated glass fiber woven (or plastic needle felt) is in-placed and cured for the rehabilitation of deteriorated pipe. This technique is entitled as cured in place pipe (CIPP) and penetrating to all over the world. Among the renovation technologies, CIPP appears less expensive and more promising than other techniques. CIPP liners are made up of several reinforcement layers impregnated with various thermosetting resins such as epoxy, vinyl ester and unsaturated polyester. Different woven geometries can be used for the felt and tube. In this study, the experimental results obtained from cured composites are given. The mechanical characteristics of CIPP tubes manufactured with different materials were given. Specifically glass fiber and synthetic felt impregnated in thermosetting unsaturated polyester resin were investigated. Standard three point flexural tests were carried out on specimens cut out from the cured liners. Beside these three point flexural tests, abrasive and erosive wear tests were also performed on these samples.

High Stress Conditions Do Not Increase Wear of Thin Highly Crosslinked UHMWPE

Introduction of highly crosslinked polyethylene has increased interest in large femoral heads, because thin acetabular liners can be used while maintaining low wear rates and larger heads decrease the incidence of instability. However, crosslinking and subsequent thermal treatments can cause decreased mechanical properties that might obviate the reduced wear under extreme conditions. To examine whether increased contact pressures would adversely affect wear in thin liners, we tested thin and thick highly crosslinked liners (3.8 mm thickness/44-mm head and 7.9 mm thickness/36-mm head, respectively) to 5 million cycles on a hip simulator under near impingement conditions. Conventional polyethylene liners (7.9 mm thickness/36-mm head) served as controls. Large femoral heads with highly crosslinked polyethylene liners as thin as 3.8 mm in thickness do not wear at a higher rate than a thicker liner of the same material, even when subjected to large contact pressures such as occur under near-impingement conditions. Crosslinked polyethylene may allow for liners that are thinner than has been traditionally accepted. This conclusion, however, is based solely on wear test results with idealized cup position, no intentional edge loading, no head subluxation, and no artificial aging. Continued monitoring will be necessary to elucidate the clinical efficacy of these devices.

Differences in Highly Cross-Linked Polyethylene Wear Between Zirconia and Cobalt-Chromium Femoral Heads in Japanese Patients: A prospective, randomized study

The purpose of this study was to compare highly cross-linked polyethylene wear between the zirconia head and the cobalt-chromium head in Japanese patients. A prospective, randomized study was performed to evaluate the outcomes in 32 hips that had zirconia heads and in 30 hips that had cobalt-chromium heads. The mean follow-up periods of both groups were same (5 years). There were no significant differences between the zirconia head and the cobalt-chromium head in the mean polyethylene linear wear per year and the mean volumetric polyethylene wear per year in the steady phase. This study indicates that zirconia head offers no benefits over metal head in terms of wear reduction at 5 years in Japanese patients who have lightweight and thin polyethylene liners.

J– T characterized stress fields of surface-cracked metallic liners bonded to a structural backing – I. Uniaxial tension

Surface crack-tip stress fields in a tensile loaded metallic liner bonded to a structural backing are developed using a two-parameter J–T characterization and elastic–plastic modified boundary layer (MBL) finite element solutions. The Ramberg–Osgood power law hardening material model with deformation plasticity theory is implemented for the metallic liner. In addition to an elastic plate backed surface crack liner model, elastic–plastic homogeneous surface crack models of various thicknesses were tested. The constraint effects that arise from the elastic backing on the thin metallic liner and the extent to which J–T two parameter solutions characterize the crack-tip fields are explored in detail. The increased elastic constraint imposed by the backing on the liner results in an enhanced range of validity of J–T characterization. The higher accuracy of MBL solutions in predicting the surface crack-tip fields in the bonded model is partially attributed to an increase in crack-tip triaxiality and a consequent increase in the effective liner thickness from a fracture standpoint. After isolating the effects of thickness, the constraint imposed by the continued elastic linearity of the backing significantly enhanced stress field characterization. In fact, J and T along with MBL solutions predicted stresses with remarkable accuracy for loads beyond full yielding. The effects of backing stiffness variation were also investigated and results indicate that the backing to liner modulus ratio does not significantly influence the crack tip constraint. Indeed, the most significant effect of the backing is its ability to impose an elastic constraint on the liner. Results from this study will facilitate the implementation of geometric limits in testing standards for surface cracked tension specimens bonded to a structural backing.

Ultra High-Stress Liner Comprising Diamond-Like Carbon for Performance Enhancement of p-Channel Multiple-Gate Transistors

We report the demonstration of strained p-channel multiple-gate transistors or FinFETs with a novel liner-stressor material comprising diamond-like carbon (DLC). In this work, a DLC film with very high intrinsic compressive stress up to 6 GPa was employed. For FinFET devices having a 20 nm thin DLC liner stressor, more than 30% enhancement in saturation drain current I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Dsat</sub> is observed over FinFETs without a DLC liner. The performance enhancement is attributed to the coupling of compressive stress from the DLC liner to the channel, leading to hole mobility improvement. Due to its extremely high intrinsic stress value, significant I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Dsat</sub> enhancement is observed even when the thickness of the DLC film deposited is less than 40 nm. The DLC liner stressor is a promising stressor material for performance enhancement of p-channel transistors in future technology nodes.

The increase of sustainability in cylinder manufacturing

To satisfy the needs of a demanding and competitive market, Amtrol-Alfa decided to allocate its resources in a new innovative composite cylinder. The CoMet cylinder consists of a thin steel inner liner, wrapped in a commingled glass and polypropylene fibre inside a plastic jacket, which exceeded our expectations. Safety and environment are on the top of Amtrol-Alfa’s priorities. As such, the manufacturing of the CoMet cylinder has no dangerous emissions to the environment, in comparison with thermoset traditional processes, and uses inert products such as PP and HDPE. Regarding recyclability, the steel can be reprocessed, the commingled fibres can be chopped and used in injection processes, including the HDPE exterior jacket that can also be chopped and re-injected. The use of only recyclable products contributes to a better environment. The design was thoroughly studied, so that the handling is less aggressive to the costumer. The cylinder exterior is also very important, not only because the new design may look more ergonomic and elegant, but also because it is cleaner and safer. CoMet lightweight cylinder integrates in one cylinder, the Past and the Future, the Proven and the Innovation, in an elegant compromise.

Preventing Mercury Vapor Release from Broken Fluorescent Lamps during Shipping

Fluorescent lamps are estimated to annually release 1 t of mercury into the air in the United States; transport of used lamps may play an important role in these emissions. In 1999, the U.S. Environmental Protection Agency added lamps to the universal waste rule to encourage recycling by allowing shipment to recycling facilities by common carrier. The rules required that lamp packaging must be structurally sound and adequate to prevent breakage but did not address vapor release. In 2005, a requirement was added that packaging must be designed to prevent the escape of mercury into the environment, but this change does not apply to fluorescent lamps. The goal of this research was to compare mercury vapor containment among different packaging configurations. In 10 replicate experiments of 5 different packages containing 40 broken, used, low-mercury lamps, two 6-hr samples of airborne mercury vapor concentrations were taken in a well-mixed sealed chamber held at 83 ±2 °F. Average chamber concentrations ranged from 0.977 mg/m3 for a single cardboard box to 0.004 mg/m3 for a double cardboard box with a plastic-foil laminate bag sandwiched between the boxes. In comparison to the single cardboard box, a single box with an unsealed thin plastic liner lowered mercury concentrations in the chamber by 52%, single or double boxes with a thicker tape-sealed plastic bag lowered concentrations by 90–92%, and a double box with a ziplock plastic-foil laminate bag lowered concentrations by 99.7%. The latter was the only configuration capable of maintaining airborne concentrations below all occupational exposure levels. Standards more specific to mercury containment are needed for packages used to ship fluorescent lamps to recyclers. Results from this study suggest that an effective packaging design should minimize the effect of cuts from broken glass while also preventing the release of mercury vapor from broken lamps.