Numerical FEM Analysis Research Articles

Mechanism of Rock Mass Detachment Using Undercutting Anchors: A Numerical Finite Element Method (FEM) Analysis.

Undercutting anchors are structural elements used in construction and geotechnics to stabilize both structures and soils. Their main applications include stabilizing slopes and embankments, reinforcing foundations, and providing support during tunnel construction and other underground works. The authors propose the use of these anchors in rock mass detachment technology. This article presents a comprehensive analysis of the mechanism behind rock mass detachment using an undercutting anchor. Particular attention is given to the influence of parameters such as the fracture energy of the medium and the coefficient of friction between the medium and the anchor head on the detachment process of rock elements during anchor expansion in the drilled hole. Numerical FEM analysis was employed to model the effect of changes in the shape and size of failure cones under varying simulation conditions. The discussed problem is crucial for evaluating the effectiveness of this anchor design under non-standard conditions, particularly in the unconventional destruction of rock media.

Multidisciplinary design and manufacturing of a Tesla pump prototype

To widen the range of hydraulic efficiencies of boundary layer pumps, a full design methodology has been proposed in order to identify critical issues for their performance and manufacturing. The methodology integrated a 2D numerical code, CFD and FEM analyses, coupled with manufacturing assessments as feedback mechanism. Considering budget constraints and in-house machining capabilities, a quick first prototype was produced. Analyses of the design are pointing out that the volute design initially chosen will not help to achieve an increase in the overall efficiency. The curves of head achieved with 2D and CFD are in agreement, but the latter determines the losses with larger accuracy, thus achieving lower values of head. The 2D model shows limits in the determination of the efficiency, effectively corrected by the CFD analysis. Critical parameters as disc thickness and gap between discs will require a more sophisticated assembly process and materials outsource. The proposed methodology could be used as a reference for the design and performance evaluation of this kind of turbomachinery in the future. The procedure lead to a prototype design, whose optimal efficiency slightly lower than 30 % was achieved at 5000 rpm with 0.3 mm disks gap.

A Model of an Extending Front Loader

Front loaders used in agriculture are characterized by a compact structure, which limits the scope of their application. The loading possibilities are expanded by designing front loaders equipped with telescopic arms. This design increases the loader’s working area, making it easier to load trucks. It is necessary to work on the arm extension drive and perform strength analyses on the new structures. This article presents a FEM numerical analysis of the structure of an extending front loader and an assessment of the state of stress and the value of displacements under the influence of load. This study discusses the advantages and disadvantages of front loaders compared to telehandlers and the legal requirements and standards for the design of front loaders in Europe. This work presents the concept of loader arm movement and assesses the effectiveness of using hydraulic motors coupled with a screw gear. The obtained results prove that the newly designed extending front loader system is safe and stable.

Development of a FEM procedure for evaluating the pressure profile in the industrial wheel and fatigue strength analyses

Industrial wheels are heavily loaded components that undergo severe cyclic stress conditions. Thus, the design of the rims must include a wide fatigue study which articulates in laboratory and field tests, analytical and numerical analyses and comparison of the experimental and computational results. This paper presents the study approach applied in the study of a 25 in rim for earth-moving machines manufactured by Moveero. The rim was subject to a design update which provided the reduction of the thickness from 11 mm to 9 mm. We decided to study the interaction tire-rim because it's a critical zone. The failures affected the area of the seat radius of the fixed flange of the rim, which resulted to be the most stressed part of the rim because of the bending actions of the tire on the flange. In order to deepen the cyclic mechanical behaviour of the component, laboratory inflation and rolling tests were carried out in Woodridge USA considering several combinations of inflation pressure and radial load applied to the wheel. The strain data from the tests were analysed to develop a reverse empirical model for the contact pressure between tire and rim. Once the load diagram applied to the flange for each test was estimated, FEM static simulations could be performed on a 3D model of the rim through SolidWorks Simulation. The stress fields obtained were then used for fatigue FEM numerical analyses which could return an evaluation of the predicted life of the component under several load conditions.

Deformative Response of Sheltering Structures Under the Debris Flow Impact

A relevant issue in the development of disaster risk reduction strategies is played by design of mitigation measures aimed at reducing risk to acceptable values. For rapid landslides, such as debris flows, sheltering structures are very common mitigation measures realized in exposed areas that allow to protect elements at risk and to stop flowing mass. For the design of these works, the debris flow–structure interaction mechanism is very important. The paper focuses on the evaluation of debris flow–structure interaction mechanism in earth reinforced embankments based on an uncoupled analysis of the interaction in two flow cases (dominant static and dynamic). In particular, a novel approach to evaluate the horizontal stress distribution at different time of the impact phenomenon along the upstream face height of deformable sheltering structures considering the dominant flow component has been proposed. First, impact force over the time against structure is calculated. Subsequently, assuming that debris flow is completely stopped by embankment according to a scheme of accumulation of material behind the obstacle, the deformative response of different geometrical types of embankment is obtained by FEM numerical analysis for considered flow cases. The results of numerical analyses are discussed in terms of horizontal displacements in different control points in sheltering structures. The analysis showed that the deformative response of two geometries of embankments depends on dominant static or dynamic components of impact force.

Morphology of cracks and comparison of load‐bearing capacity of joints of AAC masonry walls

AbstractStructural problems of wall joints in masonry structures are often neglected. This has its historical justification: with the traditional binding of the walls and relatively durable walls, the damage was rare. Currently, with the constant striving to simplify the structure, the introduction of new technologies and materials, damage and failures are becoming commonplace. Replacing the traditional masonry bond with fasteners significantly affects the operation of the entire structure and its possible cracking. The paper presents the results of experimental tests of wall joints made of autoclaved aerated concrete (AAC) masonry elements. Reference models consisting of two wall panels connected perpendicularly with a traditional masonry bond and models with the same geometry but with a modified connection method—using various types of connectors popular on the market (plates, rods, nets) were tested. The shape and size of the research models and the construction of the test stand were determined on the basis of the analysis of current knowledge, pilot studies and FEM numerical analyses. The mechanisms of cracking and damage as well as the behavior of different types of fasteners were compared. The analyses concerned load‐bearing capacity and the morphology and damage mechanism of the models.

Evaluation of rockburst energy capacity for the design of rock support systems for different tunnel geometries at El Teniente copper mine

Rockburst events have been a serious problem for many years in many mines worldwide, and in particular at El Teniente mine in Chile. El Teniente is the largest copper mine in the world, located in the Andes Cordillera where high stress levels are present due to intensing mining activity in addition to complex geology. Consequently, the study and management of the rockburst threat are necessary. In this work, the case of the Diablo Regimiento (DR) mine within El Teniente is studied. The energy capacity of dynamic support systems is determined for different tunnel geometries based on two kinetic methodologies, using data from DR. Initially, rockburst potential is determined by means of a stress analysis around different tunnel geometries through the boundary elements method. In the first methodology a yielding zone (YZ) is estimated for each excavation geometry using the finite element method FEM. The second methodology involves the definition and determination of a critical strain energy (SE) around each excavation geometry using a FEM numerical analysis. In both cases, peak particle velocity PPV is estimated by a scaling law, which is subsequently adjusted due to tunnel amplification effects. According to the results, and knowing the working energy capacity applied in DR mine, it was found that the values of energy capacity for the rock dynamic supports were better estimated by the YZ-PPV approach than by the SE approach.

A Study of Lateral Resistance of Block Breakwater Combined with Piles

Three-dimensional FEM numerical analysis was performed to understand the behaviors of blocks and piles according to the horizontal load for the block breakwater combined with piles. The Modified Mohr-Coulomb model, the improved version of the Mohr-Coulomb model, was applied for the ground modeling. The cases when the pile is embedded only into the block, embedded to the riprap layer (H = 4.29 cm), and embedded to the ground down to 2H, 3H, and 4H were examined. The results of the laboratory model experiment and the numerical analysis showed similar horizontal resistance force-displacement behaviors. The pile showed rotational behavior up to the embedment depth of 1H~2H and bending behavior in the case of 3H~4H depth embedment. When the embedment depth of the pile is 3H or more, the pile shows a bending behavior, so it can be considered that the pile contributes significantly to the horizontal resistance of the block breakwater. The results of this study will be used for various numerical analyses for real-size structure design.

Ring Hoop Tension Test for yield strength estimation: Numerical analysis for a novel correlation method and applicability for mechanical testing of tubes and pipes

The tubes and pipes manufacturing industry characterizes the mechanical properties of their products with a wide selection of standards, but most of them are qualitative testing methodologies. To estimate the mechanical properties from a quantitative point of view there are limited options in standards. In that sense, the standard tensile test is the preferred alternative by the manufacturers, but this option limits the mechanical estimation for the longitudinal direction of the tube–pipe product. Particular efforts have been made to design an alternative mechanical testing procedure to characterize the mechanical properties in the hoop direction of pipes and tubes. The Ring Hoop Tension Test (RHTT) was designed to fill this gap, but it shows limitations related to the required tooling and the influence of the frictional contact between the tooling and the ring specimen. In the nuclear industry, the Small Ring Test (SRT), a miniature test derivated from the RHTT, has been investigated in recent years. In this investigation, a novel RHTT was designed to overcome the limitations of SRT and RHTT, and a new procedure was implemented to estimate the yield strength of tubes and pipes. Numerical FEM simulations were performed to reach an optimum estimation method for the yield strength with the specific geometry of the SRT and a wide selection of pipe geometries with the RHTT. A set of hypothetical materials were designed to perform these analyses, taking into account the influence of Young’s modulus, proportional limit, hardening coefficient (based on the Ramberg–Osgood law), and presence of Lüders bands straining. To verify the results obtained from this numerical FEM analysis, experimental tests (standard tensile tests and RHTTs) and metallographic analysis were performed on aluminum Al 6063 T6 and copper C12200 R360 tubes, showing the capability of this optimized RHTT to estimate the yield strength in the hoop direction for anisotropic tubes and pipes.

Non-Contact Diagnostics of the Geometry of a Historic Wooden Building as an Element of Periodic Safety Assessment.

The article presents a method of non-invasive diagnostics of a historic wooden church, built in the 18th century. Over the hundreds of years of its use, changes in the geometry of the structure have been observed. This article presents the requirements of so-called architectural and geodetic survey and the method of using terrestrial laser scanning to create a three-dimensional solid model of an object. The diagnostic tests performed made it possible to perform analysis based on a so-called point cloud, which is a virtual representation of a real object. In order to determine the basic parameters of the building, the area and volume of all rooms were determined. It was found that the object exhibited deformations that cannot be explained solely as a result of imperfections during climb and normal wear and tear during operation. Therefore, the changes in shape were assessed in detail by means of an assessment of the verticality of the pillars supporting two levels of the church, the verticality of the walls, and the inconsistency of the floors, as well as the shape and horizontality of the roof edge. Additional InSAR and FEM tests of the object’s location on the ground allowed identification of the cause of the object deformation as the influence of inhomogeneous groundwater relations under the building. Without prophylactic measures, this deformation phenomenon can be expected to worsen. The tests described should therefore be considered as essential in subsequent diagnostic cycles and permit future extended numerical FEM analysis.

Calculation Model and Numerical Validation of Horizontal Capacity of Micropiles with Different Section Forms

With the popularized application of micropile for slope reinforcement, there are many kinds of pile section form, such as single steel bar, multisteel bar, and tube. In order to obtain the theoretical calculation model of horizontal capacity of micropiles with different types, numerical simulations for two common conditions, namely, soil‐soil and soil‐rock, were carried out to study micropile reinforced slope’s deformation and failure regulation. The dominated indicator for micropile horizontal capacity was acquired. By using the equivalence principle, four kinds of micropiles’ capacity calculation model were deduced. Then, FEM numerical analysis was used for validation. The results show that the flexural capacity of micropile is a critical and dominated indicator which should be considered seriously in slope reinforcement design. When the ultimate flexural capacity is reached, the displacement of micropile reinforced slope will increase rapidly. The primary factor affecting the flexural capacity of micropiles is pile diameter, followed by section reinforcement ratio. The calculation results of the calculation model of flexural capacity proposed in this paper are close to those of numerical ones and are safer. The calculation model can provide reference for micropile selecting and slope reinforcement design, especially for quick design of emergency engineering.

Numerical analysis of the effect of embedment depth on the geometry of the cone failure

This paper presents the results of a numerical FEM analysis of the effect of embedment depth on the extent of the failure zone (cone failure) under the effect of an undercut anchor. For the establishment of the other affecting quantities, the formation of the value of the cone failure angle of the rock medium depending on the embedment depth was analysed. The problem is interesting as regards aspects of rock mass loosening during pull-out of undercut anchors. As a result of the analysis, a significant effect of embedment depth on propagation and the extent of cone failure has been found. The increasing value of embedment depth significantly decreases the extent of the failure zone measured on a free rock surface. The increasing value of cone failure angle limits the potential interaction of failure zones in multi-anchor systems.

A Method to Optimise Semi-Trailers with the Use of FEM Analysis and Durability Tests with a Road Simulator

This paper presents a method developed by Wielton company – a manufacturer of trailers and semi-trailers – for the optimization of semi-trailer’s construction, supported by FEM analysis and the modern road simulator – a test stand included as part of the method for optimising semi-trailers. The aim of the research was to optimize the process of developing a technical measure in terms of shortening the time of implementing new products while guaranteeing high durability and functionality of the products. As a result of the optimization of the construction with the use of FEM analysis and the road simulator, the semi-trailer as a new product for sale is delivered quickly and possible defects of construction are eliminated on early stage of new product development. The method assumes the following stages of the development process: determination of input data to the process, development of a 3D model, FEM numerical analysis (static and dynamic), development of an optimized 3D model based on numerical analyses, construction of the first prototype, prototype validation tests using the road simulator and other test stands. Important feature of the developed method to optimise construction is connected with specific data achieved from FEM analysis and used in tests with the road simulator. The effect of using presented method is the elimination of 98% errors in construction and technology. These errors concern not only the key parts of the semi-trailer, i.e. the body and the frame, but also less important components, i.e. fixing of tanks and boxes, ladder, spare wheel basket, extinguisher mounting. The method to optimise semi-trailers developed in Wielton have many advantages, such as: limiting the risk of launching breakthrough solutions on the market, faster increase in vehicle competitiveness, optimizing vehicle construction, reduction of production time and costs, and as a consequence - faster implementation of new products, reducing the number of complaints and service costs, increasing the value and prestige.

Fatigue tests and numerical analyses of the PAWO autonomous electric vehicle

The following article presents fatigue testing and FEM numerical analysis of an autonomous electric vehicle, PAWO autonomous operational support platform. The purpose of the study, which was carried out in the ŁUKASIEWICZ – Automotive Industry Institute, was to verify the structure of the platform by forcing in three axes on the position: a table with six degrees of freedom "MAST", as well as conducting fatigue numerical analyses, allowing to determine places critical for fatigue endurance. This will be the starting point for the modification of the structure, and also will allow you to identify places that you need to pay attention to during tests and subsequent operation. The results of these tests allow us to determine critical places due to fatigue strength and possible intervention before starting field tests with a complete vehicle, as well as to detect places that should be noted during tests, inspections and tests, and in development versions of the vehicle.

Systematic Analysis Method for the Unusual Large Displacement in the Excavations in Soft Soil Area

Based on a subway station excavation construction project in the soft soil area in Nanjing, an informationized monitoring scheme was conducted during the construction of excavation, and the theories of displacement prediction were introduced into the scheme for the evaluation of the horizontal displacement of the retaining structure and the settlement of the surroundings around the excavation. Based on these theories and the monitoring data, a numerical simulation based on the commercial FEM numerical analysis software, Midas GTS NX, was conducted to simulate the whole construction process. To handle the large displacement of the retaining structure observed during the construction, the actual soil layers’ status discovered by excavating, which can reflect the physical characteristics of the soil, the construction condition, and the variation trend of the monitoring data, was used in the back analysis of the factors that induced the large deformation of the retaining structure, and the analysis result was fed back to the countermeasurement organization and design such as erecting temporary steel strut. The effectiveness of these measurements in the aspect of the reduction of the deformation rate was verified, which can provide reference to the design and construction of a similar project in soft soil area.

Maximising the efficiency of Menard pressuremeter testing in cohesive materials by a cookie-cutter drilling technique

Menard pressuremeter testing has been widely used in geotechnical engineering applications for 40 years and is an important technique in determining in-situ horizontal stress distributions. In this study, Menard pressuremeter testing is combined with a “cookie-cutter” insertion technique to determine horizontal stresses for a soft-rock in an operational Australian mine. The method presents an alternative to the Self-Bored Pressuremeter, with cookie-cutter drill rods allowing for sample recovery and further laboratory testing. The method accommodates for the presence of gravel and hard layered materials that present a risk of damage to cutting shoes of Self-Bored Pressuremeter devices. The combination of a sonic drill rig, coupled with the cookie cutter rods produces a close tolerance pocket resulting in “pseudo self boring pressuremeter tests”. The undrained shear strength, unload-reload shear modulus and in-situ horizontal stress are presented from pressuremeter tests conducted in the region for the first time. The undrained shear strength was observed in the range of 0.47–0.57 MPa, the unload-reload shear modulus between 17.43 and 18.25 MPa, the lift-off pressure in the range of 0.35–0.61 MPa. The K0 of coal was equal to 1, with interseam materials ranging from 2.1 to 3.5. Results of the cookie-cutter insertion method are compared with conventional drilling methods, with the cookie-cutter insertion test providing results in good agreement with both advanced triaxial laboratory tests and FEM numerical analysis. Cookie-cutter pressuremeter tests were conducted on cohesive soils at Australia's second-largest open-pit mine, with pressuremeter test results presented for Victorian brown coal for the first time.

Experimental and numerical investigations on slender panels with holes under symmetrical localised loads

Perforated steel girders under a single or combined in plane loading have been largely studied in the literature. However, such investigations were trusted on the numerical modelling and FEM analysis and due to the lack of experimental results in most cases, the accuracy of the numerical model and the consideration of imperfections in the FEM analyses are open to reflexion. In this paper, a series of experimental tests are performed to study the post-critical behaviour of perforated steel girders. Ten full scales steel girders were tested under uniaxial compressive force. Amongst them, four were used as control specimens whereas a circular hole was located in the center of the other six. The parameters such as the geometry of the web plate, the position of the hole and the plate slenderness are found as those most influencing the post-critical behaviour. Finally, the experimental results were used to validate the intensive numerical analyses. The results obtained showed the strong influence of combined geometrical imperfections and residual stresses on the mid-plane Von Mises stresses.

Vertical continuous compound casting of copper aluminum bilayer rods

A vertical continuous compound casting technology for the production of rotationally symmetric bilayer rods consisting of brass CuZn37 and aluminum AA7075 was developed. The interface of the metallurgically bonded semi-finished products was composed of four intermetallic layers and an anomalous eutectic area of Al2Cu (θ-AlCu), Al solid solution (α-Al), and other intermetallic precipitates. The intermetallic layers were CuZn (β-CuZn), a suggested two-phase region of Al3Cu5Zn2 (τ-AlCuZn) and Cu5Zn8 (γ-CuZn), Al4Cu3Zn (τ′-AlCuZn), and AlCu (η2-AlCu). The correlation between the process parameters casting speed, cladding temperature, and tool tempering and the interface formation was studied. The experimental investigations were accompanied by a numerical FEM analysis. The casting speed and the cladding temperature were found to be key factors, that influence the formation of a cohesion between the joining partners.

A FEM analysis of the settlement of a tall building situated on loess subsoil

Abstract In order to correctly model the behaviour of a building under load, it is necessary to take into account the displacement of the subsoil under the foundations. The subsoil is a material with typically non-linear behaviour. This paper presents an example of the modelling of a tall, 14-storey, building located in Lublin. The building was constructed on loess subsoil, with the use of a base slab. The subsoil lying directly beneath the foundations was described using the Modified Cam-Clay model, while the linear elastic perfectly plastic model with the Coulomb-Mohr failure criterion was used for the deeper subsoil. The parameters of the subsoil model were derived on the basis of the results of CPT soundings and laboratory oedometer tests. In numerical FEM analyses, the floors of the building were added in subsequent calculation steps, simulating the actual process of building construction. The results of the calculations involved the displacements taken in the subsequent calculation steps, which were compared with the displacements of 14 geodetic benchmarks placed in the slab.

Generating the cloud of points from the phase images

This article deals with the generating the cloud of points from the phase images. These phase images are similar to phase images which are generated during non-destructive testing using an infrared camera. In the first step the model of sample with the defects is created in the CAD software. Next the lock-in method is applied to the results from the numerical thermal FEM analysis and the phase images are created in the software MATLAB. Phase image representing the 2D image of the material at a certain depth under the surface of the model. From these phase images the coordinates of the cloud of points are generated in the MATLAB.