Ensuring fire safety during the operation of oil and gas equipment based on the results of compact specimens tests

The paper considers the application of the test method of compact specimens to assess the degree of damage of steel elements of oil and gas equipment. According to experimental data, an analytical dependence was obtained linking the degree of damage to the index of the specific fracture work, intended to assess the possibility of safe operation of explosive and fire-hazardous equipment.

Properties of epoxy-thiokol materials based on the products of the preliminary reaction of thioetherification

In order to improve the adhesive and physical-mechanical properties of epoxy-thiocol compositions cured without heat treatment, we propose to carry out the reaction of interaction between thiokol mercaptan groups and oxirane cycles of epoxy resin at an elevated temperature before introducing a curing agent, and then use the product of this thioetherification reaction for curing at room temperature. The temperature range of the thioetherification reaction (90–1800С) was determined by the method of differential scanning calorimetry. The optimal temperature (1600С) and duration of the preliminary thioetherification reaction (2 hours) were determined, which ensure the maximum level of adhesive strength and physical-mechanical properties. It was shown that composite materials based on the products of the thioetherification reaction significantly outperform analogs based on mechanical mixtures of epoxy resin and thiokol in terms of cohesive and adhesive strength, deformation capacity, fracture work and specific impact strength. The impact resistance and shear strength of adhesive joints are especially significantly increased during the curing of the compositions without external heat supply.

Fracture Behavior of Modified Polymer Materials by Digital Image Correlation Method

Polymer materials play an important role in today's social development, and become important materials in industry, agriculture, national defense and other fields. With the further development of modern engineering material technology, polymer materials, together with information technology and biotechnology, promote the progress and development of society. The performance and quality of modified polymer materials have also entered the research field of vision of various industries and become the focus of exploration and analysis. The following is the research on the fracture behavior of modified polymer materials with the help of digital image correlation method. The purpose of this paper is to clarify the basic fracture work, shaping work and other fracture work parameters of various modified polymer materials, and grasp the root cause of fracture work parameters of modified polymer materials, so as to clarify the modification processing parameter means of these polymer materials.

Arthroscopy of the Pediatric Elbow: Review of the Current Concepts

As surgeons have become more familiar with elbow arthroscopy, the indications for arthroscopy of the pediatric elbow have expanded to include contracture releases, fracture fixation, treatment of osteochondritis dissecans (OCD) lesions, correction of elbow deformity, and debridement of soft tissue and bony pathologies. The treatment of various pathologies via an arthroscopic approach demonstrates equal, if not better, efficacy and safety as open surgery for the pediatric elbow. Arthroscopy provides the unique advantage of enabling the performance of extensive surgeries through a minimally-invasive approach, and it facilitates staged interventions in cases of increased complexity. For fracture work, arthroscopy enables direct visualization to assess reduction for percutaneous fixations. While future research is warranted to better evaluate the indications and outcomes of pediatric elbow arthroscopy, this update article presents a review of the current literature, as well as several innovative cases highlighting the potential of arthroscopy.

Influence of Laboratory Long-Term Aging on Selected Fracture Parameters of Asphalt Mixtures

The paper presents the influence of laboratory aging simulation on fracture properties determined on 150 variants of asphalt mixtures. The fracture properties were determined by two different test approaches—semi-circular bending test (SCB test) and three-point bending test on beam specimens (3-PB test). The aging was simulated according to one of the methods defined in EN 12697-52 (storage of test specimens in chamber at temperature of 85 °C for 5 days). The evaluated group of variants covered asphalt mixtures for all road layers. The group was further divided according to used bituminous binder (unmodified vs. modified) and reclaimed asphalt content. The results showed that strength parameters (flexural strength and fracture toughness) increase with aging. It further shows that fracture work provides more complex information about the cracking behavior. For the aging indexes, it was found that for mixtures with modified binders and mixtures which did not contain reclaimed asphalt (RA), the values were higher. The aging indexes for fracture work showed different results for both performed tests.

Investigation of fracture of cast aluminum-matrix composite materials with various fillers under shock loading conditions

Aluminum-matrix composite materials based on commercial aluminum AD0 have been investigated. SiC powder, whiskers and Al2O3 nanofibers were chosen as fillers. It was found out that the selected fillers slightly increase density and have the modifying effect on the microstructure. The maximum grain refinement (by 35.3%) was achieved in the composite modified with Al2O3 nanofibers. This composite exhibits a quasi-brittle fracture pattern and the greatest fracture work.

Fiber orientation effect on fracture toughness of silk fiber-reinforced zeolite/HDPE composites

The aim of this work is to investigate the fracture toughness and deformation of silk fiber (SF)-reinforced zeolite (Z)/high density polyathylene (HDPE) composites. The chopped SFs are arranged in the thickness middle of the dry mixture of Z/HDPE powder that has been prepared in a mold. Composites were produced by the compression molding to produce double-edge notch tensile (DENT). The fracture toughness characterization was carried out based on essential work of fracture method. The results show that the presence of SF increased the essential fracture work even though the non-essential fracture work for Z/HDPE was higher than S-Z/HDPE. The evolution of plastic zone growth coincides with the growth of the fracture process zone (FPZ) whose height has no effect on energy consumption.

Method of calculating the gear ratios of the cones of tricone drill bits

The process of rock destruction under dynamic impact on it through two technological criteria in the form of specific contact and specific volumetric fracture works is evaluated. Specific contact and specific volumetric fracture work are used to study the physical and mechanical properties of rocks. The efficiency of rock destruction during well drilling with tricone bits functionally depends on the relative specific contact and specific volumetric fracture work. It is stated that the criteria for evaluating the performance of tricone bits in certain forms are functions of the triad: bit-rock-energy. The disclosed physical nature of the kinetic criteria and the obvious functional dependence on the geometric parameters of these drill bits are an objective basis for constructing a methodology for improving the dynamics of new designs and modifications. The parameters of the kinetic passport of the bit are calculated and presented in tabular and graphical forms as functions corresponding to their coordinates of the cones of the roller cutters and the bottom of the well. Experience in solving optimization problems based on a comparative analysis of kinetic (dynamic) criteria has shown that a) when improving almost any design of a cone bit, it is necessary to use the initial geometrical parameters of the buttons and their number b) to ensure that the supports of adjacent cones are equally loaded along the path of leveling the minimum volumetric fracture work of crowns adjacent cones.

Impact-Specific Essential Fracture Work of Banana Fiber Reinforced Low-Density Polyethylene Composites

The aim of this study is to investigate the behavior of banana fiber (BF)-low-density polyethylene (LDPE) composite fracture toughness. The LDPE pellets are transformed into powder form which is then functioned as a matrix reinforced with banana fiber (BF). The composites were formed by injection molding techniques which are followed by atmospheric-pressure annealing at 90°C for 24 hours. The composite fracture toughness behavior was evaluated using the essential work of fracture (EWF) approach. The results show that fracture toughness which is characterized by essential fracture work (we) value increases by the presence of BF up to 5 wt.%. However, the we value starts to decrease in the composite with BF content of 6 wt.%. There is a mismatch about the phenomenon of non-essential fracture work. Stress-whitened zones can be seen and observed but non-essential fracture work based on curves is a negative value.

Comparison of the Relative Long-Term Field Performance among Various Warm Mix Asphalt (WMA) Pavements

The use of warm mix asphalt (WMA) has increased greatly over the past decade because it provides potential to lower energy demands, reduce emissions, and increase haul distances. However, questions remain about the long-term performance of WMA pavements, including whether different WMA technologies can provide the same field performance. In this paper, field rutting and cracking (transverse and longitudinal) performance data for chemical, organic, and foaming WMA technologies are compared pairwise. Thirty-four WMA-WMA pairs from 13 field test roads are included, which cover different pavement ages, traffic volumes, pavement structures, WMA technologies, and four climate zones across the United States. For the WMA-WMA pairs that exhibited statistically different performance, their material properties were investigated further to identify potential factors that could be used to characterize such field differences. The results indicate that, generally, no statistical performance differences are evident between the WMA-WMA pairs. However, it is worth noting that over the longer term, there are individual projects whose organic pavement sections showed statistically higher amounts of cracking than the chemical and foaming sections. Based on the laboratory testing results on field cores, it is suggested that the greater amounts of transverse cracking exhibited by organic pavements may be caused by organic’s lower mixture fracture work density and lower binder failure strain values compared with those of the chemical and foaming sections. The greater amounts of longitudinal cracking exhibited by the organic pavements may be caused by organic’s higher mixture indirect tensile strength, lower mixture fracture work density, and lower binder fracture energy values compared with those of the chemical and foaming sections.