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The purpose of this paper is to present a novel reflow profile optimization method using mechanical reliability estimation of micro‐ball grid array (μBGA) solder joints, based on the heating factor, Q_η is introduced, where the coupling effect of reflow temperature and time on the mechanical reliability of μBGA joints is considered.

The method presented is actualized through vibration fatigue tests. First, a two‐parameter Weibull distribution is used to model the collected data of vibration fatigue lifetime for different Q_η. After that, two explicit functions are deduced in a unified mathematic expression form, which give an intuitionistic description of the mean time to failure and reliability of solder joints against induced variable Q_η, thus revealing definitely the effect of Q_η on the mechanical fatigue lifetime of solder joints suffering from cyclic vibration loading. Finally, for a specified reliability goal, how to choose proper Q_η values, based an improved Golden Section Search arithmetic, is discussed.

Numerical analysis and calculation are performed. The results show that the solder joints made at Q_η near 510 have higher mechanical reliability, and those reflowed farther away this optimal value have less reliability.

This paper presents a useful and applicable solution to achieve reflow profile optimization and process control for a quantitative mechanical reliability estimation of μBGA solder joints.

Improving reliability is a key factor in reducing the cost of wind energy, which is strongly influenced by the cost of maintenance operations. In this context, this paper aims to propose a degradation model that describes the phenomenon of fault propagation to apply proactive maintenance that will act on the cause of failure to prevent its reoccurrence as well as to improve future system designs.

The methodology adopted consists in identifying the different components of a wind turbine, their causes and failure modes, and then, classifying these components according to their causes of failure.

The result is a classification of the different components of a wind turbine according to their failure causes. From the obtained classification, the authors observed that the failure modes for one component are a failure cause for another component, which describes the phenomenon of failure propagation.

The different classifications existing in the literature depend on the nature, position and function of the different components. The classification of this study consists in grouping the components of a wind turbine according to their failure causes to develop a degradation model considering the propagation of failure in the field of wind turbines.

The purpose of this paper is to formulate a benchmark to increase the tyre curing press production rate while minimizing tyre curing press downtime and maintenance cost with the help of a maintenance management technique based on overall equipment effectiveness (OEE).

The methodology is based on determining the OEE of tyre curing press before and after rectifying the causes of failures. The failure mode and effect analysis (FMEA) technique is used to find out the root causes of repetitive failures in tyre curing press by using the risk priority number.

A significant change in the value of OEE is observed after rectifying the repetitive failures, which were determined using the FMEA technique. Thus, it is concluded that the OEE and FMEA assist in improving the industrial performance and competitiveness of the production equipment studied.

This study is limited to determining the OEE of single equipment only, not the whole production system. Manufacturing facilities are dependent on the operating environment; therefore a comparison of two different manufacturing plants based on the OEE value would not be justified.

This study can be applied in any tyre manufacturing industry in order to take competitive benefits, such as reduction in equipment downtime, increased production and reduction in maintenance cost.

The angle from which the paper approaches the bottleneck problem in a tyre production line is original for the studied company and shows positives results. It allows the company to apply the same approach in its other production equipment, lines and factories to achieve improvement in industrial performance and competitiveness.

To solve the reinforcement congestion, mechanical anchorage is increasingly popular in use instead of conventional hook rebar. However, the bond performance between the rebar and concrete and the range of stress transfer between the two are still not well understood. The purpose of this study is to study the bond performance and failure mechanisms between reinforcement and concrete around an anchorage zone in a structural element.

In this study, simulations were carried out by 3D RBSM (Rigid Body Spring Model). This approach divided a problem of interest into elements, namely concrete and steel elements. And to simulate the failure of anchorage of RC, the steel element size is set according to the geometry complexity of the reinforcing bar. By using this method, two simulation cases of anchorage failure were carried out.

This paper shows that simulations demonstrated good agreement with experimental data in terms of anchorage capacity, crack pattern, and failure mode. This indicates that RBSM analysis can simulate the failure behavior governed by complex cracks.

This paper indicates the analytical approach to investigate the anchorage performance of RC.

Polymer rapid tooling (PRT) inserts can be used as injection moulding (IM) cavities for prototyping and low volume production but lack the robustness of metal inserts. Metal inserts can withstand high injection pressure and temperature required, whereas PRT inserts may fail under similar parameters. The current method of parameter setting starts with using the highest pressure setting on the machine and then fine-tuning to optimize the process parameters. This method needs modification, as high injection pressures and temperatures can damage the PRT inserts. There is a need for a methodical process to determine the upper limits of moulding parameters that can be used without damaging the PRT inserts.

A case study analysis was performed to investigate the causes of failure in a PRT insert. From this, a candidate set-up process was developed to avoid start-up failure and possibly prolong tool life. This was then tested on a second mould, which successfully avoided start-up failure and moulded 54 parts before becoming unusable due to safety issues.

Process parameters that are critical for tool life are identified as mould temperature, injection pressure, injection speed, hold pressure and cooling time.

This paper presents a novel method for setting IM process parameters for PRT inserts. This has the potential to prevent failure at start up when using PRT inserts and possibly extend the operating life of the PRT inserts.

The purpose of this paper is to implement the six sigma (SS) strategy in a bag sector under actual operating circumstances based on defining-measure-analyze-improve and control (DMAIC). During the project, several statistical tools and methods have been used efficiently to create inferences. Thus, to measure and enhance system efficiency, the author calculate reliability, availability and maintainability (RAM) indices. Based on this research, the author show how the SS method and RAM analysis are very helpful in determining maintenance intervals, as well as in planning and organizing the appropriate maintenance strategy.

This study introduces the step-by-step application of the DMAIC methodology for the identification and reduction of bag production line downtime and examines the present operations management. Thus, statistical techniques are used to analyze the failure and repair database. Pareto analysis, histograms and descriptive statistics at the machine and line-level of the historical data were conducted. Trend and serial correlation testing validated the hypothesis of independence and identical distribution of database was performed. In addition, with their best fit allocation, the RAM of both the bag production line and its machines was estimated at separate mission times.

The main goals of the applied method are to understand the nature of the downtime patterns and to accurately and quantitatively estimate the RAM characteristics of the bag production system. The assessment defines the production line's critical points, requiring further enhancement through an efficient maintenance approach. Therefore, by improving plant efficiency and safety, the author can decrease unplanned downtime and equipment failures.

This research is expected to serve as an attempt to conduct SS DMAIC methodology through RAM assessment and its impact on system efficiency under actual circumstances. The benefit of the methodology is that the manufacturing process is continuously monitored by suitable indicators, the use of which leads to a continuous improvement cycle.

Manufacturing organisations are expected to produce their products with prompt delivery using better supply chain activities. Starting from the procurement of raw materials to the delivery of final products, there are inevitable losses occurring due to major time delays in supply chain activities. Hence it is essential to study, understand and track these major time delays by developing futuristic supply chain risk management strategies. This paper reports a research which was conducted to meet this requirement. During this research, major time delays were investigated by conducting a questionnaire supported interview based survey in 15 manufacturing organisations. On analysing the responses, pilot strategies for achieving loss reduction have been proposed. The paper is concluded by pointed out the necessity for developing dynamic models for achieving loss reduction and continuous improvement.

This paper presents the results of a case/simulation study that evaluated a number of potential maintenance policies for a flexible manufacturing system (FMS). Empirical data were used to structure the operation of the FMS, and to simulate its failures and repairs on the shop floor. Five maintenance policies – corrective, 30‐day preventive, 90‐day preventive, on‐failure opportunistic, and 30‐day opportunistic – were compared on four performance criteria: equipment utilization, machine downtime, through‐put, and average flow time. The “30‐day opportunistic” policy performed best overall, although the “corrective” policy was a close second, outperformed only in the area of equipment utilization. The “on‐failure opportunistic” policy performed poorly on every measure of system performance.

The purpose of this paper is to investigate the mechanical behavior and propagation of cracks of numerical granite samples through the Brazilian split test and to provide a reference for predicting the behavior of real granite samples.

The numerical models of granite containing two fissures are established using the parallel bond model (PBM) and the smooth joint model (SJM) in PFC2D. The peak stresses, number of cracks and anisotropic ratios are obtained to study the influence of the mineral composition and the angle of inclination of rock bridge on the strength, failure mode and deformation characteristics.

The numerical results obtained show that the mineral composition has a marginal influence on the peak stress. When the angle of inclination of rock bridge β increases, the peak stress drops to its minimum value at β = 90° and then gradually increases to a relatively low level. The behavior of cracks falls into three categories based on the distribution of cracks. By analyzing the stress–strain curve and the process of crack propagation for sample No. 4 with β = 60°, it is found that the process of failure can be divided into four stages and tensile cracks dominate. The anisotropic ratios of peak stress and a number of cracks obtained show that the peak stress is low anisotropic and the number of cracks is medium anisotropic.

This paper presents a numerical simulation method to analyze mechanical behavior and propagation of cracks under different conditions. The proposed method and the results obtained are useful for predicting the behavior of real granite samples in laboratory and engineering projects.

The purpose of this paper to study the tensile strength of the fused deposition modelling (FDM) printed PLA part. In recent times, FDM has been evolving from rapid prototyping to rapid manufacturing where parts fabricated by FDM process can be directly used for application. However, application of FDM fabricated part is significantly affected by poor and anisotropic mechanical properties. Mechanical properties of FDM part can be improved by proper selection of process parameters.

In the present study, three process parameter, namely, raster angle, layer height and raster width, have been selected to study their effect on tensile properties. Parts are fabricated as per ASTM D638 Type I standard.

It has been observed that the highest tensile strength obtained at 0° raster angle. Lower value of layer height is observed to be good for higher tensile strength because of higher bonding area between the layers. At higher value of raster width, tensile strength is improved up to certain extent after which presence of void reduces the tensile strength.

In the present investigation, layer height and raster width have been also varied along with raster angle to study their effect on the tensile strength of FDM printed PLA part.