A fundamental characteristic of the fuel injection process is the amount of fuel injected as well as the instantaneous fuel mass flow rate introduced to the combustion chamber.1 The way the fuel is delivered by the injection system in modern diesel engines affects the performance, the noise, and the pollutant emissions.2,3 Hence, measurement and control of these characteristics has been one of the most important objectives in diesel engine research and many studies have been carried out to understand the behavior of the flow in the most used nozzle types.3,4 To obtain reliable injected mass quantities and mass flow rate measurements, many methods and techniques have been developed to acquire correctly these parameters; some of these methods are mentioned and explained by Arcoumanis and Baniasad.3 The measurement technique most frequently used nowadays is the Bosh method rate meter,5 which is a measurement device designed to obtain the injection rate from pressure waves created inside a fuel-filled tube.6 The data acquired with this experimental tool is carefully processed to eliminate noise and offsets from the signals. The objective of this study is to propose a methodology to correct the cumulative phenomenon in the mass flow rate signal by employing a methodology based on signal manipulation by numerical solutions combined with iterative techniques, removing the effects of the external phenomena that change the real injection development, and obtaining reliable results.
For the structural evaluation of bridges, various tests are usually performed to know the structural properties such as natural frequencies, dynamic responses, deflections, and strains.1,2 In addition, it is important to monitor the variation of these properties as well as damages to evaluate the structural integrity of bridges.3,4 One of these properties is vertical deflection of bridge girders. Thus, a lot of applications of this method to various problems can be found, such as the studies of shape memory alloys18 and time-dependent materials.19 In addition to the simplicity of measurement, the recent progress of high resolution and handy digital cameras with zoom lenses has led the method to various new applications. The effect of random pattern on an object surface is also investigated by measuring the bridge surfaces with and without random pattern because the paint of random pattern that is found in solid mechanics applications is not possible for real bridges.
A new technique has been presented to characterize the internal geometry of diesel injection nozzles. This technique is based on the impression of silicone molds. The advantages of this technique, compared with other techniques, are that it is possible to see and measure internal zones of the nozzle like the inlet curvature radius, and it is a non-destructive method. The technique has been validated, with positive results.
In the recent years, full-field measurement techniques like moiré, moiré interferometer or grid methods have become more popular in the experimental mechanics community. Here, Piro and Grediac show that advances in printing technology make it possible to produce grids with lower pitches. They also demonstrate that a suitable choice of film, glue and printing technology allows the transfer of these grids on specimens.
Railway ballast plays a vital role in ballasted railway tracks as it provides the support to the railway superstructure and redistributes train/track loads from railway sleepers to the track subgrade. This article highlights the applicable features of modal analysis, which are proven to be nondestructive, convenient, effective, and accurate, in order to replace the railway ballast as an alternative technique to the traditional criterion using the load-deflection tests.
The first paper of the present series appearing in Experimental Techniques highlighted the increased need and opportunity for applying experimental techniques in the field of pipeline integrity.1 The series' second paper2 presented the analysis of strain data acquired by using postyield strain gages bonded inside the metal loss areas of different pipe specimens loaded with internal pressure. At those points, much resistance is offered to the longitudinal strains by the thick walls parallel to the metal loss strip, as can be noticed by the small longitudinal strain values.2 A table was also introduced, summarizing tests that were performed in order to validate calculation procedures for predicting burst pressures of defective pipes, and procedures or products for repairing and reinforcing such pipes.
[...] the US Air Force's F-22 Raptor consists of 25% carbon-epoxy composites by weight, and the Joint Strike Fighter (F-35 Lightning II) is about 25-30% composite by weight.1 According to analysis presented in Committee on Materials Research for Defense After Next,2 fiber-reinforced polymer composites have the potential for achieving a 20-25% performance improvement over the next 15-25 years; it can also be argued that monolithic materials are unlikely to achieve property improvements of this magnitude. [...] a serious design concern for use of advanced composite materials as structural elements in aerospace applications is that they are more susceptible to damage due to foreign object impact, as compared to, for example, metals.3 As future aerospace systems will rely more heavily on fiberreinforced polymer composites, it is crucial that composite materials offer not only structural integrity but also impact protection.
The experimental setup and procedure for the study of the impact response of composites in the presence of an electric field are presented in this article. The experimental results obtained in this study allow us to conjecture that the maximum load capacity sustained by unidirectional carbon fiber polymer matrix composite plates during the impact increases in the presence of the DC electric current applied to the plates.
This paper presents a device, based on a split Hopkinson pressure bar (SHPB) setup, by which it is possible to obtain stress vs. strain for a wood specimen at high deformation rate, high temperature and high steam pressure. The need for determining the mechanical properties of wood not only at high deformation rate but also at high temperature and pressure is motivated by the need to model the wood chip refining process in mechanical pulp-ing. At mechanical chip refining, e.g. in thermomechanical pulping processes, preheated wood chips together with added water are fed into the centre of a refiner which in essence consists of two circular discs. Most often one disc is stationary and the other is rotating. The wood chips are transported radially between the discs due to inertia. On their way, due to impacts from radial bars on the discs, they are eventually broken down to individual fibres and fibre fragments. The device presented here is an SHPB set-up, modified so that the bars and the specimen are encapsulated in a pressure vessel within which the temperature is constant. In this way effects of temperature gradients in the bars are avoided. Pilot tests have been carried out which verify the intended per-formance of the device.
In the past, tensile/compressive tests that give the elementary mechanical properties of materials such as Young's Modulus, Poisson's ratio, yield stress, and ultimate strength were common practice. If careful attention is paid to the product specifications, one notes that the least significant bits of the analog to digital converter is corrupted by readout noise so that the sensor's actual dynamic range is estimated to be 10.5 bits.5 To have independent estimates of the displacements in the following analyses, the shift δ between consecutive ZOIs is equal to the ZOI size L^sub ZOI^. When 3 × 3 measurements are considered with an identical separation between two neighboring points of L^sub 0^/2, the constant B in Eq. 2 decreases, that is, B = [radical]2/3 [asymptotically =] 0.8.8 In terms of strains, the corresponding standard uncertainty is equal to 10^sup -5^ with a minimum gage length L^sub 0^ of 400 pixels.
The narrow distribution of fine droplets, the large diameter of the nozzle, and the direct/inexpensive operation of the printing system are the major strengths of EHD printing. Collagen pattern was firstly and successfully achieved by EHD printing. Our method is direct, rapid, and cost effective for patterning cell-adhesive proteins and subsequently for locating animal cells. EHD printing will become an important technique in the study of cell-to-cell communication and cell-to-scaffold interactions. EHD printing technique will be further developed to build three-dimensional cellular constructs for tissue engineering.
The failure pressures measured in the laboratory tests of the tubular specimens were compared with those predicted by four assessment methods, namely, the American Society of Mechanical Engineers (ASME) B31G method,9 the Det Norske Veritas (DNV) RP-FlOl for single and for complex and interacting defects,10 the RSTRENG effective area method,11 and a recently developed method called mixed type of interaction method (MTI).8 ASSESSMENT OF PIPELINE WITH CORROSION CLUSTERS Corrosion defects in pipelines are assessed as metal loss defects that are located on the internal or external pipe surfaces and are by nature irregular in shape.
Many experimental investigations show the vaned diffuser inlet condition can greatly alter the performance map of the compressor stage. The gain in efficiency and pressure ratio may be achieved by vaned diffuser in the centrifugal compressor. Because of the limitation of the operating range, this solution is not common in production compressors.
The present article deals with laboratory tests carried out to (a) fully understand and report how the reinforcement layers of composite material help steel pipe withstand pressure loading; (b) compare the behavior of different fiber-reinforced composite repair systems applied to metal loss internal and external defects in pipeline pressure test specimens; and (c) collect data to experimentally validate the application of the RSF concept as a means for measuring the effectiveness of composite sleeve repair systems applied to pipeline.