bluuebunny/crossref_metadata_2025 huggingface dataset:
Pipe Stress and Deflection During an Integrity Dig
Authors: Naderi Ali , Deng Ruoqi , Yu Deli , Kania Richard , Li LePing
Published: January 2021

During a pipeline excavation, additional pipe stress and deflection can be produced due to altered soil support beneath the exposed pipe, which might bring in additional integrity concerns for the pipe under assessment. Classical beam theories and soil-spring modeling are inadequate for the complex pipe-soil interactions and boundary conditions. The objective of the present study was to develop a computational model that can be used to predict pipe stress and deflection during an integrity dig. The pipe-soil interaction was modeled with 3D elements using surface-to-surface contact approximation in ABAQUS. The pipe was assumed to be initially buried, then exposed for 12, 20, 30 and 34 m subsequently to mimic a buried pipeline under step-by-step excavation. The results indicated that the depth of soil support is a dominant factor for the pipe stress and deflection during an integrity excavation, which has not been previously investigated. Significant axial stress and strain in the longitudinal direction were produced by excavation, which may increase the risk of failure for the pipe that is suspected of circumferential defects. Furthermore, nonuniform soil support could cause substantial pipe deflections and stresses that may trigger an integrity dig. The model may be used to estimate the pipe stress and deflection prior to an integrity dig based on the soil conditions.
Full Encirclement Engineered Laminated Steel Sleeve System for Repairs and Augmentation of Pipelines: The Engineering Development, Validation Test Results, and Implications for Mitigation of Both Stress and Strain Dependent Integrity Threats
Authors: Laughlin Shawn , Leewis Keith , Alexander Chris
Published: January 2021

A full encirclement thin layer steel laminated sleeve system has been designed, developed, and optimized for pipeline integrity management applications. Development goals included the elimination of thixotropic concerns as well as the exclusion of the degradation of material properties of composite repairs. Elimination of cyclical fatigue of welded repairs and safety concerns associated with hot work were also considerations. The use of thin layer steel with a modulus matched to base pipe and steel’s homogenous isotropic properties enable axial calculations and evaluation of strain-based concerns. The thin layer steel laminated design results in extremely high fracture toughness and promotes intrinsic mitigation of potential future third party damage. The resulting system has demonstrated the reliable engineering data and analysis required for pipeline repairs and demonstrates applicability for the augmentation of existing pipes without defects.

An Engineering Critical Assessment (ECA) has been completed. This ECA follows the industry’s precedents of ASME B31G and ASME PCC-2 Article 4 type assessments and provides operators with greater functionality. This ECA has been named the Leewis Augmentation Analysis (LAA) and is presented, reviewed, and discussed.

Third party full scale ASME PCC-2 style burst testing has been completed. The results are presented. Highly instrumented tests were also conducted to determine an effective modulus of elasticity of the installed system as well as a determination of any delay in system acceptance of load. As installed, an effective modulus of 14 million psig (96526.60 MP)a with loading in layer 3 of the laminate at only 50 micro strain is reviewed. Long term creep and cyclical fatigue testing of the steel/adhesive laminate is presented and reviewed. 10 million cycles at 50% of ultimate lap shear has been achieved, which exceeds current industry practice by several orders of magnitude. The classic metal loss defect mitigation principle is reviewed and updated in light of these available technical advances. Finally, the implications for mitigation of both stress and strain dependent integrity concerns is discussed.
Relief Tanks: Parameters to Consider When Designing Relief Systems and Connections to Tanks
Authors: Perez Emma
Published: January 2021

Oil Storage facilities (terminals) are usually designed with a pressure rating lower than the rating of the pipeline transporting the fluids. During abnormal operations, terminal piping can be subject to unexpected transient pressure surges that can exceed the allowed values. Mitigations are required a common one is installing a relief system.

When a relief valve is installed, it is connected to a tank and the location of this relief tank is critical for the proper operation of the relief system and the overall mitigation of pressure surges. Relief design needs to take into account the length and layout of the piping. Facilities in the northern hemisphere contain pipes installed above ground and prone to experiencing cold temperatures during winter months. If the fluid is stagnant in these pipes, the cold weather increases the viscosity of the fluid. If the relief valve activates, the fluid that has been stagnant in the pipe needs to be pushed out of the pipe and into the tank. This requires a high pressure from the system and is directly affected by the distance of the pipe and the properties of the stagnant fluid.

This paper will show how transient pressures change for length of pipe and for varied viscosities of the stagnant fluid. With these findings, engineers can improve their understanding of the effects of temperature and length on surge pressures and they can design safer systems for liquid transportation and storage.
A Case Study of Predicting Tensile Strain Capacity of In-Service Pipelines
Authors: Lu Junfang , Fathi Ali , Yoosef-Ghodsi Nader , Tetteh-Wayoe Debra , Hill Mike
Published: January 2021

Strain-based design (SBD) method has evolved over the years for use in the construction of large-diameter, high pressure gas and liquid transmission pipelines. It has not been widely materialized for major construction projects because of the technical complexity which requires multidisciplinary expertise including, but not limited to, pipeline material properties, welding processes, mechanical testing, field construction, and weld inspection. The industry has been showing more interest in using this methodology for strain capacity assessment of in-service stress-based pipelines, especially those that are subjected to ground movement. The strain capacity assessment of the stress-based pipelines is essential to ensure structural integrity and operational safety of the pipeline. This has become more apparent due to recent incidents in pipeline industry caused by geotechnical hazards.

This paper provides a case study of assessing the tensile strain capacity (TSC) of existing modern linepipes manufactured through thermomechanical controlled process (TMCP). The TSC was predicted using two main methodologies in the public domain: the CSA Z662-11 Annex C approach and the PRCI-CRES TSC model. Actual pipeline information and construction data are used to perform TSC assessment when possible. This includes pipe material properties, welding procedures qualified on the project pipe, and test weld properties.

The predicted TSC and the estimated strain demand will allow for effective remediation decisions. This work helps to enhance pipeline strain management systems in response to the geotechnical and hydrotechnical issues and therefore fills the gaps in present day’s pipeline threat management programs in addition to crack, corrosion and mechanical damage threats. Through such a program, prevention, monitoring and mitigation strategies can be deployed to existing stress-based pipelines, especially in areas where pipeline strain is identified as a potential risk.
Automated Error Identification During Nondestructive Testing of Pipelines for Strength
Authors: Kornuta Jeffrey A. , Thorsson Solver I. , Gibbs Jonathan , Veloo Peter , Rovella Troy
Published: January 2021

The United States Pipeline and Hazardous Materials Safety Administration (PHMSA) recently revised the federal rules governing natural gas transport. PHMSA added a new section on the verification of pipeline material properties for pipeline assets with insufficient or incomplete records. This section permits the use of nondestructive examination (NDE) technologies to estimate material properties, which include yield strength (YS) and ultimate tensile strength (UTS), if several conditions are satisfied. These include that NDE measurement accuracy and uncertainty be conservatively accounted for, that the NDE technology be validated by experts, and that proper calibration procedures be implemented. One such NDE technology is Instrumented Indentation Testing (IIT), which can be used to estimate YS and UTS.

Precise quantification of any NDE technology’s precision and accuracy requires consistent identification of test errors: if an error occurs during a measurement such that the data should be excluded from subsequent analyses, analysts need to be alerted to the data characteristics prior to including these results. These testing errors are distinct from the inherent measurement uncertainty due to both random error and systematic error. Any NDE measurement will contain some degree of uncertainty; however, faulty measurements exhibiting clearly identifiable errors must be excluded from subsequent analyses to maintain the integrity of the data set.

Accordingly, this paper extends Pacific Gas and Electric’s (PG&E’s) previously reported efforts on IIT uncertainty quantification by presenting observations of a specific type of IIT error related to tool fixturing that has occurred during in-situ testing and describing the characteristics of how this error was exhibited in the test data. Once this test error was clearly identified, isolated, and was found repeatable; pre-processing algorithms were adapted to detect and alert NDE technicians to this error during testing, ultimately evolving NDE work procedures. This paper discusses this process from the initial recognition of a test error, to the adaptation of appropriate detection algorithms, and then finally to resulting revisions in operator procedures. Ultimately, these modifications have improved validation data quality and reduced the error rate of IIT measurements collected in the field.
Comparison of Feasibility of a Standard Reliability-Based Approach and a Bayesian Network Approach for Integrity Management of a Northern Canadian Liquids Pipeline
Authors: Koduru Smitha D. , Abdolrazaghi Mona , Yoosef-Ghodsi Nader
Published: January 2021

Integrity management of a northern Canadian liquid pipeline required a unique approach due to the presence of methanol-induced, short, axially-oriented, internal stress corrosion cracking (iSCC) adjacent to girth welds. Previous studies focused on investigation of the susceptibility to iSCC, crack detection performance of inline inspection tools, and leak rates due to iSCC. The current feasibility study aimed to identify an approach to estimate the probability of leak due to iSCC that uses information from previous investigations and handles the data gaps. Two probabilistic approaches — a standard reliability-based approach and a Bayesian Network approach — were compared based on a number of criteria related to effective use of existing data, flexibility of the framework, and ability to iteratively improve the results. The results of the comparison indicate that a hybrid of the two approaches is an ideal way to develop a comprehensive integrity management tool.
Composite Sleeve Repair in the North American Regulatory Environment
Authors: Ortiz Xavier , Jungwirth Dan , Behnamian Yashar , Sharahi Hossein Jiryaei
Published: January 2021

Composite sleeve repairs have been used in the pipeline industry for the last 25+ years. Fiberglass sleeves (e.g., Clock Spring®) were initially introduced in the market and are still being used as a proven pipeline repair method. For the last 15+ years, new composite materials have been introduced in the industry to provide a wider variety of repair options depending on the type of imperfections being repaired. Regulations in the U.S.A. and Canada share some requirements regarding design, installation, testing, and assessment of composite sleeve repairs. The U.S. Department of Transportation (DOT) through the Pipeline and Hazardous Materials Safety Administration (PHMSA) recommends the use of repair methods consistent with industry standards. The 2019 version of the Canadian CSA Z662 Oil and Gas Pipeline Standard includes requirements for testing and qualification according to the American Society of Mechanical Engineers (ASME) regulation PCC-2 or ISO/TS 24817, and requirements for conducting an engineering assessment to determine the subsequent maximum stress on the pipe sleeve. This paper compares the regulatory requirements for pipeline composite sleeve repairs in the U.S.A. and Canada; it describes some of the options for composite sleeve repair, and reviews engineering assessments of methodologies for composite sleeve repair.
Deer Mountain Case Study: Integration of Pipe and Ground Monitoring Data With Historical Information to Develop a Landslide Management Plan
Authors: Babcock Joel , Dewar Doug , Webster Joel , Lich Tyler
Published: January 2021

Deer Mountain is an active landslide complex near Swan Hills, AB. Pembina owns two pipelines that traverse the landslide. Prior to abandonment, four leaks occurred on the NPS 8 pipeline due to interaction of circumferential stress corrosion cracking and ground movement. The NPS 10 pipeline is operating and has not leaked, but has previously been strain relieved in several locations.

To develop and execute a geohazard management plan for the operating pipeline, Pembina integrated pipe and ground monitoring data with historical information into a geographic information system. Locations of bending strain areas, strain gauges, pipe wall assessment (PWA) anomalies, slope inclinometers, and piezometers were cross-referenced with previous leak sites, historical dig sites, historical strain reliefs, and areas of shallow pipe burial.

Overlaying the PWA with pre-existing pipe data allowed for identification of segments with a higher density/magnitude of suspected soil to pipe interactions. Strain monitoring, strain relief, and a surface pipeline segment were prescribed. A detailed monitoring plan was also produced for the landslide complex.

This case study presents the process of integrating data, specifying monitoring/mitigative measures, and implementing strain relief at four locations. Additionally, the paper will discuss the design of the surface pipeline segment.
Material Properties and Flaw Characteristics of Vintage Girth Welds
Authors: Jia Dan , Wang Yong-Yi , Rapp Steve
Published: January 2021

Vintage pipelines, which in the context of this paper refer to pipelines built before approximately 1970, account for a large portion of the energy pipeline systems in North America. Integrity assessment of these pipelines can sometimes present challenges due to incomplete records and lack of material property data. When material properties for the welds of interest are not available, conservative estimates based on past experience are typically used for the unknown material property values. Such estimates can be overly conservative, potentially leading to unnecessary remedial actions. This paper is a summary of PRCI-funded work aimed at characterizing material properties and flaw characteristics of vintage girth welds. The data obtained in this work can be utilized to understand and predict the behavior of vintage pipelines, which is covered in a companion paper [1].

The material property data generated in this work include (i) pipe base metal tensile properties in both the hoop (transverse) and the longitudinal (axial) directions, (ii) deposited weld metal tensile properties, (iii) macrohardness traverses, (iv) microhardness maps, and (v) Charpy impact transition curves of specimens with notches in the heat-affected zone (HAZ) and weld centerline (WCL). These data provide essential information for tensile strength, strength mismatch, and impact toughness. In addition to the basic material property data, instrumented cross-weld tensile (ICWT) tests were conducted on CWT specimens with no flaws, natural flaws, and artificially machined planar flaws.

The ICWT tests provide an indication of the welds’ stress and strain capacity without and with flaws. For welds with even-matching or over-matching weld strengths, the CWT specimens usually failed outside of the weld region, even for specimens with natural flaws reported by non-destructive examination. Having over-matching weld strength can compensate for the negative impact of weld flaws.

All tested girth welds were inspected using radiography and/or phased array ultrasonic testing. The inspection results are compared with the flaws exposed through destructive testing. The ability of these inspection methods to detect and size flaws in vintage girth welds is evaluated.
Operational Modal Response Characterization of a Buried Pipe Structure
Authors: Chen Haobin , Hugo Ron , Wong Ron Chik-Kwong , Park Simon
Published: January 2021

As a novel non-invasive structural health monitoring (SHM) technique for application to buried pipelines, in-situ vibration-based detection offers an approach to achieve continuous monitoring. Modal characteristics are often quantified using vibration signals, with traditional modal analysis performed using either impact-response testing or mechanical-shaker excitation. Both methods, however, are not suitable for a buried pipeline. In this research work, the operational modal response of a buried-pipe structure is investigated, and the application of transient flow event detection is presented. Experiments are conducted on a buried 160-inch horizontal stainless-steel pipe section with an inner diameter of 2-inch. Soil compaction is performed to 95% of the maximum dry density (proctor compaction). During experiments, water flow rate through the pipe (Reynolds number) is increased and turbulent pressure fluctuations provide the varying structural excitation source. Vibration measurements are made using one tri-axial and four single-axis accelerometers. Accelerometers directly mounted to the pipe are to perform on-pipe measurement to investigate the operational modal response of the buried pipe structure. Accelerometers positioned in soil are to investigate the vibration transmission through the soil in both the horizontal and vertical directions, examining the feasibility of the modal response characterization through non-contact measurement. The operational modal response collected through on-pipe measurement showing that vibration energy is decreased due to the soil and the vibration of the axial direction (along the pipe) has highest sensitivity than the other two directions with increasing Reynolds number. The abnormal signal induced by a transient flow event is visualized using short-time spectral analysis, and its propagation and source are determined using acoustic methods. The vibration transmission of the buried pipe propagating through the soil is heavily attenuated both horizontally and vertically.
Qualitative and Semi-Quantitative Model for Estimating the Probability of Failure at River Crossings
Authors: Sancio Rodolfo B. , Varela Patricia , Vance David , Abdolmaleki Kourosh , Sen Millan
Published: January 2021

Pipeline river crossings are typically managed by using a combination of flood monitoring, ground inspections, integrity assessments, and remediations. Using a probabilistic model to assess the likelihood of failure at river crossings would enable combined consideration of all factors that contribute to the failure threat, provide site rankings to support discrete mitigation prioritizations, allow for evaluation of whether a crossing is acceptable in regard to a risk target, and provide a “check” to the deterministic integrity management methods. This paper describes two models for estimating the pipeline probability of failure at river crossings.

The first model is a qualitative scoring model that can be easily implemented by operators and consultants. This model employs a weighting-factors approach to consider the multiple variables that contribute to pipeline exposures and overstress given exposure. The results may be applied to threat rank diverse crossings, as well estimate the probability of failure at a crossing relative to that at historical failure sites.

The second model is a semi-quantitative model that 1) estimates the likelihood of a crossing exposure occurring, 2) estimates the associated scour length, 3) assesses the pipelines critical span length, and 4) quantifies the probability that a span length longer than the critical span length could form. This model may be applied to achieve the same goals as the qualitative model, and also compare the probability of failure at a river crossing to a reliability target. Due to the complexity of this model and the paper length limits, it is conceptually described within this paper.

The results demonstrated that the model output site rankings correlated reasonably with those estimated by pipeline integrity program managers, the scour depth and length prediction results were consistent with measured historical scours, and the pipeline probability of failure at the assessed river crossings were within expected ranges.
Free Vibration and Thermal Fluid Structure Interaction Simulation of Functionally Graded Pipe by Modeling As Layered Structure
Authors: Su Ziyi , Inaba Kazuaki , Karmakar Amit , Das Apurba
Published: January 2021

Functionally graded materials (FGMs) are advanced class of composite materials which can be used as the thermal barrier to protect inner components from the outside high temperature environment. In FGMs, the volume fraction of each constituent can be tailored made across the thickness for desired applications. In this work, the simulation of FGMs in pipes is considered. Despite the wide application of pipes in machinery, those pipes would suffer from many safety problems, such as thermal stress, cavitation, fracture etc. Application of FGMs to the piping systems could lead to some new solutions accounting for safety measures and higher service life. However, the complex phenomena within the fluid structure interaction are hard to describe with the theoretical solution. The visualization of results from simulation will be helpful in understanding the distribution of kinds of physical quantities within the concerned model. For the simulation, FGMs are modeled as the layered structure in the standard finite element method (FEM) package based on FGM constituent law. The free vibration of the FG pipe is simulated and the accuracy of layered model is verified by numerical calculations. Further, based on the layered model, conjugate heat transfer simulations in a heat exchanger with FGMs are conducted.
On-Machine Metrology System Using Confocal Chromatic Probe and Motion Error Correction for Ultra-Precision Machine Tool
Authors: Duan Hao , Morita Shinya , Hosobata Takuya , Takeda Masahiro , Yamagata Yutaka
Published: January 2021

Aspherical or free-form optical surface machining using an ultra-precision machine tool is a common and effective method in precision optics manufacturing. However, this method sometimes causes waviness due to the machine’s motion in mid-spatial frequency (MSF) form deviations. This waviness lowers the quality of the optical surface. To address this problem, we use the waviness of the axial displacement of the ultra-precision machine tool. The waviness is obtained by a non-contact on-machine metrology (OMM) system that measures an optical flat as a correction reference curve, which is used to correct the surface of the workpiece to reduce the effect of waviness in advance. The OMM system consists of a displacement probe and a machine tool axis position capture device. The probe system uses a confocal chromatic probe on an ultra-precision machine tool to evaluate the form deviation of the workpiece with 1 nm resolution. The axis position capture system uses a signal branch circuit of linear scale on each axis from the ultra-precision machine tool. The OMM system is tested in terms of accuracy and repeatability. In comparison to the results of the shaper cutting of an oxygen-free copper (OFC) workpiece with feed-forward correction, we were able to reduce the profile error from 125.3 nm to 42.1 nm in p-v (peak to valley) and eventually also reduced the waviness.
Improvement of Thermal Deformation in a Newly Developed Steel CFRP Composite Ball Screw
Authors: Yoshioka Hayato , Saito Shunya , Kato Jun , Shinno Hidenori , Goto Shunsuke , Hori Nobumitsu
Published: January 2021

Machine tools are required to realize high precision and high efficiency machining by various industry sectors. A machine tool has some driving systems to position cutting tools and workpieces, and hence driving units are required high speed and precision positioning. However, high speed feed motion causes thermal deformation due to generated heat at friction surfaces such as guideway, feed screw, and bearings, it deteriorates positioning accuracy of driving units. Thermal deformation of a ball screw is one of large error factors of lower positioning accuracy, and a cooling system for reducing thermal deformation is installed into machine tools. Since the cooling system needs additional cost and space in machining systems, a new method for minimizing thermal deformation is required. In this study, a new structure of ball screw is proposed in order to meet these requirements. A new ball screw which has a core pipe made of CFRP was developed. CFRP is one of composite materials which have light weight and low thermal expansion. This paper presents analysis results of a simplified FEM model of the ball screw and the basic experimental results of the developed ball screw. These results confirmed that the proposed ball screw was applied to high performance positioning system in machine tools.
Performance of the Plastic Injection Molding Mold Heating and Cooling System Using Hydrogen Absorbing Alloys
Authors: Kosaka Masataka , Fukushima Yoshio
Published: January 2021

Hydrogen is expected to become one of the major secondary energy sources and to be treated as important as conventional secondary energy such as electrical energy, thermal energy and so on. Effectively, to use the hydrogen energy leads to the achievement of the low carbon society that is one of the goals of the sustainable society that is aim at the modern society. However, in the industry, there are few precedents of practical use that is using hydrogen energy. In this study, hydrogen energy is applied to plastic injection molding mold heating using LmNi4.90Mn0.10 hydride. In this paper, the thermal characteristic of heating and cooling processes of the proposal system with using the heat of formations by exothermic/endothermic reversible reactions was investigated and the effectiveness of this method has been evaluated from relationship between measured surface temperature change and amount of hydrogen absorption. As results, using this proposal system, when the time cycle of the heating and cooling processes was set about 162 seconds, the mold surface temperature difference of the heating system between these processes became 55 K and the average amount of hydrogen transfer of three cycles except for first cycle was 0.80g which was 80% value of maximum amount of hydrogen absorption.
The Proposal of Two Different-Sized Abrasives to Shorten Polishing-Process-Time and Reduce Manufacturing Cost
Authors: Tokoroyama Takayuki , Takeno Hiroaki , Umehara Noritsugu , Murashima Motoyuki , Chiba Shogo
Published: January 2021

Polishing manufactures use abrasives such as diamond or other hard materials to flatten several materials. Generally, diamond abrasive is most popular and it is costly. Although, diamond abrasives are costly, manufacturer have to use it to reduce surface roughness such as high hardness ceramics and others. In the polishing process, it is unpopular to retrieve those abrasives from reservoir of after-using them. Therefore, using diamond abrasives account for majority of processing cost. One of the concept to overcome the cost problem, it is suggested that reducing high-cost diamond abrasives and replacing cheap and soft abrasives can reduce processing-cost. In this study, to reveal the possibility of such two different-sized abrasives polishing process, polishing tests were conducted to unearth an effect of two-hardness-abrasive polishing technique to a glass disk on reducing surface roughness. An average diameter of 127 μm GC, and 1.0 μm diamond abrasive were prepared as concept abrasives. As a result, the arithmetic mean roughness of the glass quickly decreased in the case of using 127 μm GC abrasive with 1.0 μm diamond abrasive compared to only GC or only diamond abrasives.
Sensor-Less Tool Wear Estimation Based on Change in Value of Identified Parameter in Cutting Force Prediction Model
Authors: Kaneko Kazuki , Nishida Isamu , Sato Ryuta , Shirase Keiichi
Published: January 2021

Several methods have been proposed to detect tool wear in milling operation using AE (Acoustic Emission) signals or cutting force signals. However, these methods require additional sensors such as an AE sensor or a dynamometer, which incurs additional costs. For this reason, a simple tool life estimation method based on machining time is used. In this study, a sensor-less tool wear estimation method is proposed. In this method, the parameters required for the cutting force prediction are identified continuously from the spindle motor torque signal, which can be monitored within the computer numerical controlled (CNC) machine. The tool wear progress can be estimated by the continuous change in the identified parameters during milling operation. To identify the parameters continuously, a real-time virtual milling simulation is performed in parallel with a physical milling operation. In the experimental results, it was confirmed that the identified parameter corresponding to the edge force component has linear relationship with the flank wear width of cutting edge. Thus the flank wear can be estimated without any additional sensor.
Microstructure Affected Residual Stress in Direct Metal Deposition
Authors: Mirkoohi Elham , Liang Steven Y.
Published: January 2021

Residual stress build-up in metal additive manufacturing (AM) is a well-known problem that can impede the applicability of the AM parts. Residual stress may cause the part to fail due to the crack or fall out of the specified dimension. Thus, in order for a part to be used in a mission-critical application, it is important to predict the stress state within the AM part accurately and rapidly. During the thermal loading, the grain size is altered at the subsurface through dynamic recrystallization (DRx) and subsequent recovery. The yield strength of the alloys is largely determined by the size of nucleated grains, and it has a substantial influence on residual stress build-up. In this work, a physics-based analytical model is proposed to predict the residual stress considering the microstructure of the additively manufactured part. A moving heat source approach is used to predict the temperature field. Due to the high-temperature gradient in this process, the material properties are considered temperature-sensitive to capture the properties gradient affected thermal distribution. The energy needed for solid-state phase change is also considered by modifying the heat capacity using the latent heat of fusion. Due to the high-temperature gradient, the thermal stress is obtained using Green’s function of stresses due to the point body load. The total stress is the combination of three main sources of stress known as body forces, normal tention, and hydrostatic stress. High thermal stress may exceed the yield strength. The yield surface is obtained by modifying the Johnson-Cook flow stress to incorporate the effect of DRx on grain size using the Hall-Patch equation. The DRx and subsequent recovery affected grain size is predicted using Johnson-Mehl-Avrami-Kolmogorov (JMAK), model. The residual stress is then predicted using incremental plasticity and kinematic hardening behavior of the metal according to the property of volume invariance in plastic deformation and in coupling with equilibrium and compatibility conditions. The predicted residual stress considering microstructure evolution is validated by measuring the residual stress via X-ray diffraction for the In718 parts manufactured via the direct metal deposition process.
Quickest Change Point Detection in Shape Inspection of Additively Manufactured Parts Under a Multi-Resolution Framework
Authors: Jin Yu , Liao Haitao , Pierson Harry
Published: January 2021

In-situ layer-by-layer inspection is essential to achieving the full capability and advantages of additive manufacturing in producing complex geometries. The shape of each inspected layer can be described by a 2D point cloud obtained by slicing a thin layer of 3D point cloud acquired from 3D scanning. In practice, a scanned shape must be aligned with the corresponding base-truth CAD model before evaluating its geometric accuracy. Indeed, the observed geometric error is attributed to systematic, random, and alignment errors, where the systematic error is the one that triggers an alarm of system anomalies. In this work, a quickest change detection (QCD) algorithm is applied under a multi-resolution alignment and inspection framework 1) to differentiate errors from different error sources, and 2) to identify the layer where the earliest systematic deviation distribution changes during the printing process. Numerical experiments and a case study on a human heart are conducted to illustrate the performance of the proposed method in detecting layer-wise geometric error.
Feasibility and Characterization of Large-Scale Additive Manufacturing With Long Fiber Reinforced Composites
Authors: Thakur Aditya R. , Leu Ming C. , Dong Xiangyang
Published: January 2021

A new additive manufacturing (AM) approach to fabricate long fiber reinforced composites (LFRC) was proposed in this study. A high deposition rate was achieved by the implementation of a single-screw extruder, which directly used thermoplastic pellets and continuous fiber tows as feedstock materials. Thus, the proposed method was also used as a large-scale additive manufacturing (LSAM) method for printing large-volume components. Using polylactic acid (PLA) pellets and continuous carbon fiber tows, the feasibility of the proposed AM method was investigated through printing LFRC samples and further demonstrated by fabricating large-volume components with complex geometries. The printed LFRC samples were compared with pure thermoplastic and continuous fiber reinforced composite (CFRC) counterparts via mechanical tests and microstructural analyses. With comparable flexural modulus, the flexural strength of the LFRC samples was slightly lower than that of the CFRC samples. An average improvement of 28% in flexural strength and 50% in flexural modulus were achieved compared to those of pure PLA parts, respectively. Discontinuous long carbon fibers, with an average fiber length of 20.1 mm, were successfully incorporated into the printed LFRC samples. The carbon fiber orientation, distribution of carbon fiber length, and dispersion of carbon fiber as well as porosity were further studied. The carbon fibers were highly oriented along the printing direction with a relatively uniformly distributed fiber reinforcement across the LFRC cross section. With high deposition rate (up to 0.8 kg/hr) and low material costs (< $10/kg), this study demonstrated the potentials of the proposed printing method in LSAM of high strength polymer composites reinforced with long carbon fibers.
Smart Agent-Based Priority Dispatching Rules for Job Shop Scheduling in a Furniture Manufacturing Workshop
Authors: Wang Hao , Peng Tao , Tang Renzhong , Qin Wei
Published: January 2021

To meet the increasingly diversified demand, multi-variety and small-batch production has been widely acknowledged in manufacturing industry, which raises higher requirements for production scheduling. Priority dispatching rules have been widely used in job shop scheduling with many advantages, including low computational cost, high flexibility and good portability. However, it is usually hard to guarantee a globally optimal solution. Multi-Agent-based priority dispatching rules for scheduling are available to handle real complex and dynamic production environment, in the meanwhile hold a comprehensively satisfactory performance. In this paper, multi-agents are designed representing production jobs, production machines, and especially packaging process. A composite priority dispatching rule considering working conditions of job agent, machine agent and packaging agent is proposed, where the packaging agent plays a significant role in developing the proposed dispatching rule. Then, this priority rule is compared with four widely-applied rules in literature, FCFS, SPT, COVERT, and ATC. Four measures of performance, i.e. maximum completion time, tardiness time, equipment utilization, order waiting time, are employed. The results show that the proposed priority dispatching rule performs better overall, particularly in reducing order waiting time. Finally, an agent-based simulation model of a furniture manufacturing workshop is constructed using AnyLogic, to verify the proposed priority rule in dealing with random order arrivals.
Modeling and Simulation of the Phase Coarsening Process for Cocontinuous Polymer Blends
Authors: Shen Hangming , Yao Donggang
Published: January 2021

Among different phase structures in immiscible polymer blends, the cocontinuous phase structure is considered to be advantageous for load transfer and achieving good mechanical properties. Due to the presence of an interpenetrating interface, phase coarsening naturally occurs during melt processing of cocontinuous polymer blends, and harness of the coarsening kinetics is important for structural control. Existing models for phase coarsening are mostly founded on the basis of scaling or dimensional analysis while computational models embodying more realistic phase geometries are demanded. In this paper, we present a two-step computational approach for prediction of the coarsening kinetics. First, a phase-field transport equation is solved to establish an initial phase geometry. Second, a moving-boundary flow model is implemented to solve the hydrodynamic problem. Case studies are presented both in 2D and in 3D domains. An empirical model on the basis of fractional calculus is also proposed to fit the computational results. Once verified by experimental data, this approach can provide an integrated tool for assisting in the processing of cocontinuous polymer blends where phase coarsening is of concern.
Inter-Cell Scheduling Optimization With Limited Transportation Capacities for Optimization of Vehicle Numbers
Authors: Liu Qiong , Ye Qin , Mei Xu
Published: January 2021

Inter-cell manufacturing could quickly respond to market changes and save investments on equipment. The number of vehicles in an inter-cell manufacturing system is one of important factors affecting results of inter-cell scheduling and related costs. Previous literatures on inter-cell scheduling with limited transportation capacities assumed that numbers of vehicles in a manufacturing system are fixed and simply set as numbers of manufacturing cells. However, numbers of vehicles generally are determined by decision makers and might be different in different manufacturing systems. Reducing the number of vehicles could save investments and latter operation costs. To help decision makers make decisions on the number of vehicles, it is needed to explore relationships among the number of vehicles, makespan, and total costs. An inter-cell scheduling model is proposed for an inter-cell manufacturing system with flexible routes and limited transportation capacities to optimize the number of vehicles, makespan and total costs. A Shuffled Frog Leaping Algorithm (SFLA) is designed to solve the proposed model. A four-segment coding method is proposed to encode operation sequence of parts, manufacturing cells, and machines for processing operations, and vehicle allocation. A case is used to analyze relationships among the number of vehicles, makespan, and total costs. Conclusions are yielded, which would help decision makers to make decisions on the number of vehicles.
Digital Twin Enabled Mass Personalization: A Case Study of a Smart Wetland Maintenance System
Authors: Aheleroff Shohin , Zhong Ray Y. , Xu Xun , Feng Zhenan , Goyal Pulkit
Published: January 2021

Mass personalization has been an essential paradigm in the Industry 4.0 era. Mass personalization has long been a question of great interest in a wide range of industries. There is a recognized need for a cost-effective approach for dealing with a high number of unique products and services. There has been substantial research undertaken on the role of Industry 4.0 for mass customization. The contribution of Digital Twin (DT) has received little attention within mass personalization. No known empirical research has focused on exploring relationships between DT and mass personalization. The principal objective of this project was to utilize DT for a significant number of unique wetlands. In this study, a Digital Twin architecture was developed and applied to address challenges in regards to a massive number of distinct wetlands. This study is based on an industry-led case with significant value, including scheduled maintenance, real-time monitoring, remote controlling, and predicting functionalities. The findings indicated that there was a positive relationship between Digital Twin capabilities and mass personalization. The present results highlight the detrimental value that Digital Twin has on mass personalization. The results represent a further step towards developing Digital Twin research and development.
Decomposition and Sequencing for a 5-Axis Hybrid Manufacturing Process
Authors: Xiao Xinyi , Joshi Sanjay
Published: January 2021

Hybrid Manufacturing (HM) combining Additive Manufacturing (AM) and subtractive machining (SM) technologies have recently been introduced and have the potential to address the shortcomings of AM, such as the poor surface finish and requires post-processing of the support structures. One such example of an HM machine is the DMG Mori Lasertec 65. These 5-axis HM machines allow for rapid deposition of material during additive manufacturing and address the issues of feature resolution, surface finish, and tolerances by subtractive machining. Additionally, these processes allow for the creation of complex geometries not possible with standard 5-axis machining. Process planning for HM is a reasonably complex manual task and could benefit from automation. Critical steps in process planning are the decomposition of the part into additive and subtractive features, sequencing all features and assigning the tool-paths for these features. This paper presents algorithms for decomposing the part and sequencing the additive and subtractive features in an automated manner, paving the way for a fully automated system for HM. Examples of a wide range of parts demonstrating the capability of the algorithm are presented.
Design of Stochastic Lattice Structures for Additive Manufacturing
Authors: McConaha Matthew , Anand Sam
Published: January 2021

With recent development of additive manufacturing methods, topology optimization, an increased focus on the generation of designs which maximize material efficiency by lightweighting has gained considerable interest. Lattice structures are one of the popular methods chosen by design engineers for constructing highly complex, functional geometries which are only manufacturable by additive processes. Stochastic lattices have been finding their way into additively manufactured geometries due to their strength at low volume fraction, as well as the ease of implementation with various generative design tools on the market. However, optimization of these stochastic lattices for maximizing part strength and stiffness is a research topic that has been largely overlooked. By tweaking stochastic lattice generation procedures, non-isotropic structures can be generated and these directional strength properties can be exploited. This paper describes a method for homogenizing the effective properties of non-isotropic stochastic lattices generated using stretched Voronoi tessellations, optimization of the stretching aspect ratio and angle within a part design space, and generation of the non-isotropic and smoothly graded Voronoi-based stochastic lattice structures for that design space. The method was applied to a case study of a cantilever beam with nine different Voronoi lattice configurations. Stiffness of parts designed using this procedure was found to be significantly higher than parts designed using an isotropic design.
Deformation Behavior of Grains Near Defects in Direct Metal Laser Sintered Inconel 718 During Indentation
Authors: Rifat Mustafa , Basu Saurabh
Published: January 2021

The present work utilizes Orientation Imaging Microscopy and Finite Element Modelling to analyse microstructure evolution in grains near defects during plane strain indentation of direct metal laser sintered Inconel 718. Defects are inevitably produced during printing of metals and they degrade the mechanical behaviour of parent components. Understanding microstructure evolution of grains present near defects can help create better predictive models of mechanical behaviour of components resulting from additive manufacturing. In this work, an ex-situ study of microstructure evolution during plane strain indentation of DMLS Inconel 718 specimens is performed. Regions that lie near volumetric porosity defects were studied. Grain Orientation Spread was utilized as a metric to quantify intra-granular deformation. It was seen that microstructure evolution of grains near defects is enhanced due to strain concentrations whereby they exhibit larger orientation spread after plastic deformation. Finite Element Analysis was used to simulate the plane strain indentation test on the specimen in which, porosity defects and roughness textures similar to those seen in the as-received specimen were programmed using the python scripting interface of Abaqus. Results from finite element analysis were compared with insights from microstructure analysis to describe evolution of microstructure during deformation near defects.
Verification of a Novel Position Verification Sensor to Identify and Isolate Robot Workcell Health Degradation
Authors: Weiss Brian A. , Kaplan Jared
Published: January 2021

Manufacturing processes have become increasingly sophisticated leading to greater usage of robotics. Sustaining successful manufacturing robotic operations requires a strategic maintenance program. Maintenance can be very costly, especially when some manufacturers unnecessarily spend resources (i.e., time, money) to maintain their equipment. To reduce maintenance costs, manufacturers are exploring how they can assess the health of their robot workcell operations to enhance their maintenance strategies. Effective health assessment relies upon capturing appropriate data and generating intelligence from the workcell. Multiple data streams relevant to a robot workcell may be available including robot controller data, a supervisory programmable logic controller data, maintenance logs, process/part quality data, and equipment/process fault and/or failure data. This data can be extremely informative, yet the extreme volume and complexity of this data can be both overwhelming, confusing, and paralyzing. Researchers at the National Institute of Standards and Technology have developed a test method and companion sensor to assess the health of robot workcells, which will yield an additional and unique data stream. The intent is that this data stream can either serve as a surrogate for larger data volumes to reduce the data collection and analysis burden on the manufacturer or add more intelligence to assessing robot workcell health. This article will present the immediate effort focused on verifying the companion sensor. Results of the verification test process are discussed along with preliminary results of the sensor’s performance during verification testing.