Foam Fracture Research Articles

Investigating the Mechanical Behavior and Energy Absorption Characteristics of Empty and Foam-Filled Glass/Epoxy Composite Sections under Lateral Indentation.

In this study, the crashworthiness behavior and energy absorption capacity of composite tubes under lateral indentation by steel rods aligned parallel to the specimen axis are investigated using experimental methods. Key parameters such as tube diameter, length, wall thickness, and indenter diameter are systematically examined and compared. Additionally, the influence of polyurethane foam fillers on damage modes and energy absorption capacity is rigorously analyzed. Contrary to conventional findings, smaller diameter specimens filled with foam demonstrate superior energy absorption compared to their larger counterparts, primarily due to enhanced compression of the foam volume. Experimental results reveal a complex interplay of damage mechanisms in composite specimens, including matrix cracking, fiber breakage, foam crushing, foam densification, foam fracture, and debonding of composite layers, all contributing to enhanced energy absorption. Increased tube thickness, length, and indenter diameter, alongside decreased tube diameter, are correlated with higher contact forces and improved energy absorption. Smoother shell fractures are promoted, and overall energy absorption capabilities are enhanced by the presence of foam fillers. This investigation provides valuable insights into the structural response and crashworthiness of composite tubes, which is essential for optimizing their design across various engineering applications.

Research and performance optimization of carbon dioxide foam fracturing fluid suitable for shale reservoir

Compared to conventional fracturing techniques, foam fracturing has numerous advantages, including good shear resistance, strong sand carrying capacity, low fluid loss, low damage, and fast return rates. It is particularly suitable for stimulation in low pressure, low permeability, and water-sensitive formations. Specifically, CO2 foam fracturing is crucial in energy savings and emission reductions, controlling the expansion of reservoir clay minerals, reducing crude oil viscosity, and improving the production of water-locked reservoirs. In this paper, we investigate the foam fracturing fluid and evaluate its performance. We selected thickeners with good foaming stability and foaming agents with excellent performance at low dosage levels, based on experimental evaluation. We finally determined the formulation of the foam fracturing fluid by analyzing the experimental data, such as foam half-life, foam mass, and viscosity. We experimentally evaluated the viscosity, static sand settling properties, and rheological properties of the fluid. After being tested on the reservoir core, the foam fracturing fluid has a viscosity of 2 mPas. Moreover, the residue content is 1.1 mg/L, the surface tension is 24.5 mN/m, and the interfacial tension is 1.5 mN/m. The fluid-carrying sand experiment of 40–70 mesh ceramic particles, commonly used in shale gas fracking, was evaluated. The sand-to-liquid ratio was set at 40% for the static sand-carrying experiment. The flow of the fluid-carrying sand was good, and the settling property was satisfactory for 3 h. We used shale reservoir cores from well W-1 to assess the rate of foam fracture, which was less than 19%. Under the experimental conditions of a shear rate of 170 S−1 and a temperature of 90°C, the viscosity of fracturing fluid was measured to be greater than 50 mPas, 90 min after shear, demonstrating the excellent temperature and shear resistance of the foam fracturing fluid. Using CO2 foam fracturing fluid can significantly improve the reconstruction effect of low permeability hydrocarbon reservoirs (especially unconventional reservoirs) and solve problems related to water resources and environmental protection during the process of oil and gas reservoir development. It will be a major factor in improving construction impacts and addressing water and environmental concerns for low permeability hydrocarbon reservoirs, particularly unconventional ones that utilize CO2 foam fracturing fluids.

Gas-Liquid Foam Dynamics: From Structural Elements to Continuum Descriptions

Gas-liquid foams are important in applications ranging from oil recovery and mineral flotation to food science and microfluidics. Beyond their practical use, they represent an intriguing prototype of a soft material with a complex, viscoelastic rheological response. Crucially, foams allow detailed access to fluid-dynamical processes on the mesoscale of bubbles underlying the large-scale material behavior. This review emphasizes the importance of the geometry and interaction of mesoscale structural elements for the description of the dynamics of entire foams. Using examples including bulk flow of foam under steady shear, interfacial instabilities, and foam fracture through bubble rupture, this article highlights the wide variety of available theoretical descriptions, ranging from network modeling approaches coupling structural element equations of motion to full continuum models with elastoviscoplastic constitutive relations. Foams offer the opportunity to develop rigorous links between such disparate descriptions, providing a blueprint for physical modeling of dynamical multiscale systems with complex structure.

Failure initiation and progression of sandwich beams under cyclic bending tests

This study presents experimental results and analysis of failure of sandwich beams with steel face sheets and polyurethane core tested in three-point bending. Firstly, a series of experiences are conducted in order to obtain the mechanical properties of the metallic face sheets and the foam core. To model the foam behavior, quasi-cyclic tests were performed by increasing the punch stroke. An exponential model is proposed describing the variation of the elastic modulus as a function of the strain. Secondly, the quasi-static and quasi-cyclic bending tests are carried out leading to failure of the sandwich beam. The results of the quasi-cyclic bending show that the behavior of the sandwich beam is similar to the foam behavior in quasi-cyclic compression. Thirdly, a Finite Element Analysis (FEA) is performed in order to predict the observed foam fracture in bending test using a shear damage criterion for the foam core. The comparisons show a satisfactory agreement between the experimental results and the FEA predictions.

Numerical investigation of high velocity impact on foam-filled honeycomb structures including foam fracture model

An appropriate finite element model is developed to simulate the high velocity impact of projectiles on polyurethane foam filled aluminum honeycomb. First, the numerical model of the high velocity impact of the projectiles on the empty aluminum honeycomb is developed using a strain rate dependent material model. A VUMAT subroutine including two different fracture criteria proposed by researchers is developed. The fracture criterion that shows similar behavior to experimental observations, is selected. The numerical model of the projectiles impact on the foam-filled honeycomb is compared with available experimental results, and the ballistic limit velocities are predicted with good accuracy.

Modelling the Strength of Cellulose Nanofiber-Filled Rigid Low-Density PU Foams

Rigid low-density closed-cell polyurethane (PU) foams are used primarily as a thermal insulation material. The foams have to possess a sufficient strength and stiffness in order to ensure their mechanical integrity and dimensional stability in service. The mechanical characteristics of foams are enhanced by adding cellulose nanofibers to the polyol system, which both modify the foaming process and act as a reinforcement of cell struts and walls. A model of composite foam strength is developed based on a regular unit cell and assuming the onset of strut failure as the foam fracture criterion. The load-bearing capacity of foam struts is estimated by the modified Fukuda and Chou model considering the orientation of nanofibers along the strut axis. The model developed is shown to provide a reasonably accurate prediction for the nanofiber loading effect on the strength of composite foams.

Low-velocity impact characteristics of closed cell AA2014-SiCp composite foam

Deformation behaviour of closed cell aluminium alloy (AA2014) −10 wt % silicon carbide particles (SiCp) composite foam is studied under static and impact loading conditions. Foam is fabricated through liquid metallurgy route. Static compression tests are performed at an equivalent strain rate of 0.01/s and drop-weight impact tests are performed at an impact velocity of about 0.80 m/s. Based on these tests, Young's modulus, plateau stress, and densification strain of the foam are determined. Finite element analysis is used to simulate the static and impact tests and numerical simulation results are compared with the experimental results for fracture behavior of the foam. Results show the brittle but high strength characteristic of the foam. Further, experimental and simulation results shows good conformity. Based on this study, it is found that a peak load of about 520 N is required to cause the foam fracture and complete perforation under the impact test.

Fixation strength of a polyetheretherketone femoral component in total knee arthroplasty

IntroductionIntroducing polyetheretherketone (PEEK) polymer as a material for femoral components in total knee arthroplasty (TKA) could potentially lead to a reduction of the cemented fixation strength. A PEEK implant is more likely to deform under high loads, rendering geometrical locking features less effective. Fixation strength may be enhanced by adding more undercuts or specific surface treatments. The aim of this study is to measure the initial fixation strength and investigate the associated failure patterns of three different iterations of PEEK-OPTIMA® implants compared with a Cobalt–Chromium (CoCr) component. MethodsFemoral components were cemented onto trabecular bone analogue foam blocks and preconditioned with 86,400 cycles of compressive loading (2600 N–260 N at 1 Hz). They were then extracted while the force was measured and the initial failure mechanism was recorded. Four groups were compared: CoCr, regular PEEK, PEEK with an enhanced cement-bonding surface and the latter with additional surface primer. ResultsThe mean pull-off forces for the four groups were 3814 N, 688 N, 2525 N and 2552 N, respectively. The initial failure patterns for groups 1, 3 and 4 were the same; posterior condylar foam fracture and cement–bone debonding. Implants from group 2 failed at the cement–implant interface. ConclusionsThis study has shown that a PEEK-OPTIMA® femoral TKA component with enhanced macro- and microtexture is able to replicate the main failure mechanism of a conventional CoCr femoral implant. The fixation strength is lower than for a CoCr implant, but substantially higher than loads occurring under in-vivo conditions.

Two-scale study of the fracture of an aluminum foam by X-ray tomography and finite element modeling

An aluminum foam can be characterized by its architecture and by the solid phase’ microstructure. Our aim is to link the foam's morphological and microstructural features with its mechanical properties thanks to X-ray tomography and finite element (FE). An approach combining X-ray tomography at different resolutions, image processing, and FE modeling was developed to take into account the influence of the intermetallics on the foam's fracture. First, the samples were scanned with “local” tomography, where the specimen is placed close to the X-ray source. These images allowed for observing intermetallics. Then an in situ tensile test was performed in the tomograph to follow the sample's deformation at low resolution. The images obtained from local tomography were processed to create one low-resolution image of the initial sample including details from high resolution. This was done by a series of thresholding and scaling of the high-resolution images. This image was used to generate a FE mesh. A FE input file was obtained thanks to Java programs associating the elements to the phases. At the local scale, the calculated stress distribution and the images of the struts were analysed. Our work confirms that the presence of inclusions can explain the fracture of struts.

Experimental investigation and evaluation on influence of foam flow resistance in porous media

With an aim to investigate foam flow resistance in porous media, batch tests were carried out based on soil column. Foam resistance factor and foam injection pressure were selected to evaluate foam resistance ability. The influencing factors including liquid/gas/foam flow rate on foam resistance factor were studied on the basis of single-factor experiments. Also, a 2k factorial design was utilized to identify the most relevant process variable for foam injection pressure. The process variables such as injection foam size, foam quality, foam rate, and surfactant concentration in injection fluid were investigated. The results showed that foam resistance factor gradually diminished as liquid flow rate increased with a constant gas flow rate, while it increased with gas flow rate increasing with a constant liquid flow rate. The pressure distribution showed a steady downtrend across the soil column, which showed the flow uniformity of foam in soil column. It also indicated that dynamic equilibrium was reached between foam fracture and regeneration. The effects of process variables on foam injection pressure followed the order of foam quality > foam rate > injection foam size > surfactant concentration under the experimental conditions. The results indicated that the major effect on foam injection pressure was foam quality. The obtained results would provide useful information and technical support for actual in situ soil remediation when using foam-flushing technique.

Mixed-Mode Testing for an Asymmetric Four-Point Bending Configuration of Polyurethane Foams

Many efforts have been made recently to determine the fracture toughness of different types of foams in static and dynamic loading conditions. Taking into account that there is no standard method for the experimental determination of the fracture toughness of plastic foams, different procedures and specimens were used. This paper presents the polyurethane foam fracture toughness results obtained experimentally for three foam densities. Asymmetric four-point bending specimens were used for determining fracture toughness in mode I and in a mixed one, and also the influence of the loading speed and geometry of the specimen were investigated.

Refinements on fracture toughness of PUR foams

Many efforts have been made in recent years to determine the fracture toughness of different types of foams in static and dynamic loading conditions. Taking into account that there is no standard method for the experimental determination of the fracture toughness of plastic foams different procedures and specimens were used. This paper presents the polyurethane foam fracture toughness results obtained for different foam densities. Two types of specimens were used for determining fracture toughness in modes I, II and a mixed one, and also the size effect, loading speed and loading direction were investigated. The paper proposed correlations for density, cell orientation and mixed mode loading based on the experimental testing results.

A Simulation Trainer for Complex Articular Fracture Surgery

The purposes of this study were (1) to develop a physical model to improve articular fracture reduction skills, (2) to develop objective assessment methods to evaluate these skills, and (3) to assess the construct validity of the simulation. A surgical simulation was staged utilizing surrogate tibial plafond fractures. Multiple three-segment radio-opacified polyurethane foam fracture models were produced from the same mold, ensuring uniform surgical complexity between trials. Using fluoroscopic guidance, five senior and seven junior orthopaedic residents reduced the fracture through a limited anterior window. The residents were assessed on the basis of time to completion, hand movements (tracked with use of a motion capture system), and quality of the obtained reduction. All but three of the residents successfully reduced and fixed the fracture fragments (one senior resident and two junior residents completed the reduction but were unsuccessful in fixating all fragments). Senior residents had an average time to completion of 13.43 minutes, an average gross articular step-off of 3.00 mm, discrete hand motions of 540 actions, and a cumulative hand motion distance of 79 m. Junior residents had an average time to completion of 14.75 minutes, an average gross articular step-off of 3.09 mm, discrete hand motions of 511 actions, and a cumulative hand motion distance of 390 m. The large difference in cumulative hand motion distance, despite comparable numbers of discrete hand motion events, indicates that senior residents were more precise in their hand motions. The present experiment establishes the basic construct validity of the simulation trainer. Further studies are required to demonstrate that this laboratory-based model for articular fracture reduction training, along with an objective assessment of performance, can be used to improve resident surgical skills.

A double cantilever beam specimen for foam core fracture characterization

This article presents the analysis and test results for a new sandwich double cantilever beam specimen for foam fracture characterization. The foam is sandwiched between two stiff and strong aluminum adherends. The specimen is analyzed using a modified version of the classical Kanninen elastic foundation model. Finite element analysis is conducted to determine the stress state near the crack tip and compliance of the double cantilever beam sandwich specimen. Model predictions are compared to experimental compliance data and crack growth paths for double cantilever beam specimens with polyvinyl chloride and polyethersulfone foams. The elastic foundation model and finite element analysis compliance results were in close agreement with experimental data over a range of crack lengths. The experiments revealed crack kinking for double cantilever beam specimens with 25.4 mm thick cores, whereas the crack path was stable in specimens with thinner (12.7 mm) cores. The distributions of T-stress ahead of the crack tip indicate crack instability for thicker cores while thinner cores promote stable growth, in agreement with experimentally observed crack paths. Hence thinner foam cores should be considered when conducting fracture testing of foam cores. An expression for the minimum admissible length of the uncracked specimen region was determined from the foundation model.

Enhancing tensile strength and toughness in syntactic foams through nanoclay reinforcement

Nanoclay hybrid syntactic foams are developed for applications requiring high energy absorption and damage tolerance. Four types of hollow glass particles with different densities are used for fabrication. All foams are fabricated with a constant (35%) volume fraction of resin. Eight types of nanoclay hybrid foams are made by combining two volume fractions of nanoclay particles (2 and 5%, respectively) with each microballoon type. Results from tensile testing of hybrid and pure syntactic foams are compared. Microstructural characterization is performed to determine the interaction of nanoclay particles with the surrounding matrix and to study their role in altering the fracture behavior of microballoons. Results indicate that tensile strength has increased upon the addition of nanoclay particles. Modulus has decreased, which indicates a large increase in fracture strain and toughness of syntactic foams due to the presence of nanoclay particles. Presence of nanoclay particles plays a significant role in delaying crack initiation and growth, resulting in enhanced tensile strength and toughness. Low density foam fracture due to microballoon failure and crack propagation. High density foams fracture due to matrix–microballoon debonding and crack propagation around intact microballoons.

3D quantitative image analysis of open-cell nickel foams under tension and compression loading using X-ray microtomography

The deformation behaviour and fracture of an open-cell nickel foam were analysed using X-ray microtomography at the ESRF, Grenoble, France. In situ tensile and compression tests were performed at a resolution of 2 and 10 μm. The initial morphology of the foam was studied using 3D image analysis. Parameters such as the cell volume and strut length distributions, number of faces per cell, number of nodes per face and the shape of the most representative cells were determined. The cells are shown to be non-spherical due to the initial geometrical anisotropy of the polyurethane foam template and to the load applied to the nickel foam during processing. This geometrical anisotropy is shown to be related to the observed anisotropy of the elastic properties of the material using a simple beam model. In tension, bending, stretching and alignment of struts are observed. A tensile test in the longitudinal direction is shown to reinforce the privileged orientations of the cells. In contrast, a tensile test in the transverse direction leads to a more isotropic distribution of the cells. These features are illustrated by pole figures of the three axes of equivalent ellipsoids for all cells at different strain levels. Compression tests are associated with strain localization phenomena due to the buckling of struts in a weaker region of the foam. Finally, study of open-cell nickel foam fracture shows that cracks initiate at nodes during tensile tests and that the damaged zone is about five cells wide. Free edge effects on crack initiation are also evidenced.

Simulation of Hydraulic Fracturing in Low-Permeability Reservoirs

AbstractComputer-based numerical simulation can be used as a tool for analysis of fracturing treatments and prediction of postfracturing well performance. The physical problem studied involves fracture mechanics, fluid flow, and heat transfer both in the fracture and in the reservoir. The numerical model predicts fracture extension, length, and width; proppant transport and settlement; fracture closure; cleanup; and postfracturing performance under different producing conditions.The number of physical features that are customarily neglected in fracture designs have been incorporated in the present model. These include stress-sensitive reservoir properties, proper two-phase calculation of leakoff and cleanup, stress-dependent fracture permeability and temperature- and time-dependent fracturing fluid rheology.The utility and a priori predictive capability of the model is illustrated with two examples of fracturing jobs. The first example is a marginal gas well stimulated by a medium-size gelled-water fracturing job. The second example is a massive foam fracture in the Elm worth basin. In both cases, the simulator predicted results that are in good agreement with the observed productivity.

The Niobrara Gas Play: Exploration and Development of a Low-Pressure, Low-Permeability Gas Reservoir

Summary The Niobrara gas play in eastern Colorado, northwestern Kansas, and western Nebraska is a successful economic development involving an integrated, interdisciplinary exploration and exploitation strategy. This comprehensive study of the Niobrara formation gives a concise description of methods for exploration, development, production and evaluation of the Niobrara reservoirs. Introduction In 1912, the Osborne and Dunn Co. encountered a strong flow of gas in the Niobrara formation while drilling the Goodland No. 1 well (Sec. 24-T8S-R40W) near the town of Goodland, KS. The well subsequently was plugged and abandoned. In the 1930's and 1940's, several small Niobrara gas wells were drilled in the Goodland field area by Industrial Gas Co. and others for local use only. The Beecher Island field discovery well was Midfields No. 1 well (Sec. 14-T2S-R43W) in Yuma County, CO, drilled in 1919 by the Midfields Oil Co. It had estimated flow rates of up to 2 MMcf/D (57×10-3 m3/d) of gas. In the 1920's, four additional Niobrara wells were drilled in Beecher Island; however, connection to a pipeline could not be justified. By 1970, two of the four dry holes drilled to deeper formations had gas shows while penetrating the Niobrara formation. Following a study in 1972 of the known gas shows in the Beecher Island field, Midlands Gas Corp. and Mountain Petroleum Corp. air-drilled six wells in Beecher Island. Five were completed without stimulation as producers and then were connected to a pipeline. The wells averaged 20 Mcf/D (565 m /d) each, which at $0.35/Mcf ($0.35/30 m) was uneconomical. However, they proved the existence of significant gas reserves. Further investigation revealed many resistivity log anomalies and reported gas shows in the Niobrara of eastern Colorado and western Kansas. However, the play began when, in early 1974, the new high-quality foam fracture stimulation process was used for the completion of the Beecher Island field State 1-29 well (Sec. 29-T2S-R42W). The well had a prestimulation drillstem test rate of only 5.6 Mcf/D (160 m3/d). After the treatment, it had an initial potential of 721 Mcf/D (20×10 M /d), with a sustained rate of more than 150 Mcf/D (4250 m3/d). The play now extends from Chadron, NE, and south to Kit Carson County, CO (Fig. 1). The major concentration of drilling remains in the original producing area in Yuma County, CO, and in Cheyenne and Sherman counties, KS. Since 1974, 919 Niobrara wells have been drilled, of which 454 are producers in more than 60 fields; 465 wells are dry holes. At this time, very few fields are developed fully. Geology and Gas Origin The Niobrara formation chalks were deposited during the last major transgression of the western interior Cretaceous sea, which extended from the Gulf of Mexico to the Arctic Ocean. The lower member of the Niobrara is the Fort Hays, which is 40 to 85 ft (12 to 25 m) thick. The upper member is the Smoky Hill, which averages 600 ft (180 m) (Fig. 2). JPT P. 2863^

Rock mechanics aspects of hydraulic fracturing in the devonian shale : Advani, S H; Komar, C A; Chang, H Y Proc 21st US Symposium on Rock Mechanics, Rolla, Missouri, 28–30 May 1980, P701–709

The Eastern Gas Shales Project (EGSP) is investigating optimum methods and supporting rationale for stimulating gas production from Devonian shale. Innovative hydraulic fracturing techniques such as foam, dendritic, and cyrogenic fracturing are being field tested to develop commercial technology for transfer to the oil and gas industry. The supplementary model studies presented provide a rational basis for stimulation treatment design and fracture geometry prediction. This work summarizes results from a developed structural, fracture mechanics, and fluid flow model with the influence of in situ stress and shale bi-material properties. Selected comparisons with the models investigated are presented along with simulation results for a foam fracture experiment. In addition, rationale for dendritic fracturing experiments is sought by investigating the spalling zone and stress intensities associated with branched cracks. Supporting numeric results are given also. 26 references.

Analyses of an Elmworth Hydraulic Fracture in Alberta

Summary A tight gas sand with 1-µd permeability was produced, after a large hydraulic foam fracture, at rates close to predicted values. The rates of about 300 Mcf/D (8495m3/d) after 23 days would not bear the cost of development at 1979 Canadian prices. However, it is estimated that, with higher netbacks and longer fractures, commercial development would be feasible. Introduction The Elmworth gas field is located within the Deep basin near Grande Prairie, Alberta (Fig. 1). The Deep basin covers about 26,000 sq miles and appears to contain an enormous amount of gas in different-quality rocks. Masters1 has estimated the Deep basin could contain more than 400 Tcf of gas, recoverable at various levels of price and technology. Canadian Hunter visualizes the gas distribution in the Deep basin as a resource triangle. In such a distribution, the sands and conglomerates of highest porosity and permeability are at the very top of the triangle. As reservoir quality decreases, the resource triangle indicates larger and larger quantities of gas in lower-porosity and lower-permeability rocks. Near the bottom of the triangle are sands approaching 7% porosity and 1 µd in-situ permeability. Within these lower porosity rocks (7 to 11%) resides a huge ultimate potential. Detailed analyses were made of logs, cores, and tests of about 20 zones from 57 wells in a 60-township area around the Elmworth field. This study indicated that, with sufficient but reasonable economic incentives, it would be possible to recover more than 200 Tcf from the lower-quality rocks within the Deep basin.2 To obtain more information on the technology and economics required to recover this gas, Canadian Hunter performed a large hydraulic fracture over the Cretaceous Falher Zones A and B in the Canhunter Texcan Elmworth Well 11–12–71–13W6. This paper presents a description and analysis of the fracture. Petrophysical Properties The Falher Zones A and B were cored completely, and a full suite of openhole logs was run. This suite included the induction-electrical, acoustic with variable density display, compensated neutron-density, and microlog. Selected logs and the core analysis (made at atmospheric conditions) are shown in Fig. 2. Although the entire cross section of 164 ft is considered gas-bearing, less than one-half of the section is estimated to be net pay, based on analysis of logs, cores, and pressure buildups. Sixty-six feet of this section have measured core porosities equal to or above 7%; this is shown by the shaded area on the porosity curve in Fig. 2. Permeabilities above 0.1 md also are shaded. Sonic log and pressure buildup analysis indicate a net pay closer to 45 ft. The relation between fractional core porosities (f) measured at 200 psi and sonic travel time (?t) in µs/ft is described byf=0.0054?t-0.2865.