Brittle Crack Research Articles

Preparation of epoxy resin elastic particles and their application in oil well cement

AbstractTo solve the problem of high brittleness and easy cracking of cement stone, epoxy resin powder elastic particles (HEEP) were developed to improve the elasticity of cement stone. HEEP was prepared from epoxy resin and trimeric anhydride by solution polymerization. The surface wettability and particle size of HEEP were analyzed by contact angle test and laser particle size analysis respectively. Mechanical performance tests, scanning electron microscope (SEM) analysis and x‐ray diffraction analysis were conducted on the cement stone containing HEEP. The results showed that HEEP was the target product, with a hydrophilic surface and a water contact angle of 75.2° on the HEEP surface. The particle size distribution of HEEP was uniform, and the median particle size was 36.5 μm. The initial decomposition temperature of HEEP was 300°C, indicating a good thermal stability. The stress–strain curve showed that when the HEEP dosage was 3%, 6%, and 9%, the elastic modulus of the cement stone was 6.382, 4.017, and 3.148 GPa, respectively. Compared with the blank cement without HEEP, the elastic modulus was reduced by 28.3%, 54.9%, and 64.6%, respectively. This showed that HEEP could effectively improve the elasticity of cement stone. In addition, the compressive strength and flexural strength of cement stone containing HEEP can meet the requirements of on‐site applications. SEM analysis of cement stone showed that HEEP was well filled in cement stone. When the cement stone was subjected to complex stress, HEEP could effectively buffer and disperse the stress, thereby enhancing the resistance of cement stone to external force impact.

Mechanical Performance of Alkali-activated Stabilized Sandy Soil Reinforced with Glass Wool Residue Microfibers

Alkali-activated binders have been introduced as promising alternatives to conventional binders such as lime and ordinary Portland cement (OPC). However, alkali-activated materials exhibit a brittle behavior and crack formation due to tensile stresses is inevitable. To overcome these limitations, incorporation of fibers into the cementitious matrix is among the well-known techniques to improve the flexural behavior and energy absorption of the corresponding composites. The present study aimed to investigate the feasibility of using reinforced alkali-activated metakaolin as an alternative to common stabilizers to improve the engineering characteristics of sandy soil. Calcium carbide residue (CCR) was used as an alkali activator, and glass wool residue (GWR) microfibers were used as reinforcement elements to maximize waste stream utilization. Unconfined compressive strength (UCS), California bearing ratio (CBR), and three-point bending tests were performed to evaluate the mechanical behavior of the alkali-activated products. Moreover, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were employed to determine the microstructure and elemental composition of these products. The results indicate that the compressive strength and ductile behavior of the stabilized soil samples improved significantly. Furthermore, the SEM/EDX analysis of the reinforced alkali-activated samples revealed the interfacial bond between the microfibers and alkali-activated binding gel, enhancing the mechanical performance between the microfibers and cementitious matrix.

Electrochemical hydrogen permeation in wrought and electron beam melted Ti-6Al-4V alloys

Ti-6Al-4V is one of the most widely used titanium alloys. However, it is susceptible to hydrogen embrittlement, e.g. due to hydride formation. Hydrogen permeability through Ti-based alloys is affected by the rapid formation of hydride or oxide surface layers as well as by trapping in the bulk alloy. Here, we analyze and compare the electrochemical hydrogen permeation (EHP) through wrought and electron beam melted (EBM) Ti-6Al-4V alloys. Hydrogen diffusion coefficients are calculated from the permeation current transients. The effective diffusion coefficient of hydrogen in the wrought alloy is found to be an order of magnitude higher than in the AM’ed alloy. The different microstructures of the wrought and EBM alloys are found to play an important role in hydrogen distribution and phase transformation in the alloy. In the EBM alloy, hydrogen is distributed more uniformly and, consequently, more pronounce phase transformations occur, eventually leading to brittle cracking. In the wrought alloy, on the other hand, hydrogen is distributed unevenly in the bulk of the membrane, forming hydride clusters, most probably at α/β interphase boundaries. These findings suggest that the EBM Ti-6Al-4V alloy is more susceptible to HE than its wrought counterpart.

In-situ fracture toughness measurement of multilayer graphene

Understanding the fracture and failure properties of graphene is a critical step towards integrating graphene into electromechanical devices and flexible electronics. However, the exact fracture properties of graphene are hard to measure due to the atomic level thickness of graphene and its brittle nature which tends to cause it to break before accurate measurements of its properties can be made. In this paper, a method is presented for measuring the fracture properties of graphene with varying number of layers. This method utilizes a custom designed MEMS tensile tester and an effective and repeatable graphene transfer process that enables the transfer of patterned graphene structures onto MEMS devices. The fracture properties of graphene samples with different numbers of graphene layers were tested and the critical strain energy release rate of fracture was measured to be 22 J/m2, 71.3 J/m2, and 145 J/m2 for ∼ 7 layer, ∼12 layer, and ∼ 15 layer graphene, respectively. These results show that the fracture toughness of the graphene increases as the number of layers increases. This is likely due to the need for brittle cracks to propagate through multiple, weakly connected layers of the graphene for ultimate failure to occur in the graphene.

Fracture-toughness estimation from small-punch test in hydrogen exhibiting ductile and ductile–brittle fracture modes

In this study, an energy-based fracture toughness estimation method based on a small-punch test in a hydrogen environment, exhibiting either ductile or combined ductile and brittle fracture modes is proposed. For the ductile fracture mode, the energy term due to gas pressure in the small-punch test in hydrogen environment is simply added to the existing energy-based fracture toughness estimation equation. For the combined ductile and fracture mode, modified equations for the plastic energy term are proposed to correct overestimation due to brittle cracking. The estimated fracture toughness values are shown to consistent with the published API X70 and X42 test data.

A novel dealloying assisted machining method to improve the machinability of NiTi alloy as a typical high toughness difficult-to-machine material

High quality and high efficiency cutting process is of great significance to the components manufacturing related to machinability of workpiece materials. As a typical difficult-to-machine material induced mainly by high toughness, NiTi alloy faces challenges such as high cutting force and difficult chip breaking during the cutting process. To solve these problems, this paper presents a novel surface dealloying assisted machining method, i.e., the preparation of nanoporous structures on the workpiece surface with dealloying treatment, to improve the machinability of NiTi alloy. Based on high speed in-situ imaging of material removal process, the presence of dealloyed layer leads to a segmented flow mode instead of homogeneous severe plastic deformation without dealloying treatment. The change in material removal mode is beneficial to decrease the cutting force and energy and improve the machined surface quality. The embrittlement effect of dealloyed layer inhibits material plastic flow and promotes periodic crack nucleation and propagation. An analytical model is developed to characterize the brittle crack propagation, which provides theoretical basis for explaining embrittlement effect of dealloyed layer. This work verifies the feasibility and effectiveness of the proposed method to modify the machinability of NiTi alloy and provides new ideas for the development of manufacturing processes.

Effect of Heating Temperature, Holding Time and Stabilization Temperature on the Al-Foam Properties

The interest in metallic foam is increasing since their cellular structures have a unique combination of properties such as high stiffness, low density, lightweight, high specific strength, and thermal insulation. Commonly, the performance of metallic foam can be improved by the heat treatment process. However, the previous heat treatment methods still present the brittle crack path and the research on heat treatments of the metal foam properties is very limited. In this study, individual parameters in stress relieving treatment that contribute to Al-Foam properties were investigated. The stress-relieving process of the samples was performed using a vacuum furnace. The composition of aluminium foam was determined by X-Ray Fluorescence (XRF). The hardness test was conducted using a microhardness tester. Quasi-static compression test was conducted by a universal testing machine. From the SEM-EDX elemental images, it can be observed that traces of Ca, Fe, Ti, and Si have a homogeneous distribution in the Al-matrix. In the result obtained, the mechanical properties of aluminium alloy foam decrease when the heating temperature is enhanced. The mechanical properties of closed-cell aluminium alloy increase with the reduction of the holding temperature. This was due to the recovery and recrystallization process which depended on time and temperature during the heat treatment process. The mechanical properties of aluminium foam were raised after increasing the stabilization temperature. This finding was due to the vibrational atomic motion in the recovery process.

Crystallographic characteristics and mechanical behavior of laser welded joints of hot roll bending parts

In this work, laser welding was performed on the hot roll bending parts obtained by local-induction-heating bending forming. The influence of the crystallographic characteristics of the phase transformation products in different regions of the laser welded joint on the mechanical properties was systematically studied, and the reasons for the performance degradation were discussed in detail. The results show that upper-critical HAZ (UCHAZ) forms coarse prior austenite grain (PAG) and bainite, resulting in the lowest dislocation density of 2.5 × 1014 m−2 and the lowest impact toughness value of 46 J/cm2. Sub-critical HAZ (SCHAZ) forms tempered martensite, causing the joint to soften and the tensile strength to decrease by 18%. The number of variants in SCHAZ is the lowest, where short laths with smaller misorientations merge into long laths, and precipitates nucleation and growth occurs. The uniform orientation of the variants in SCHAZ forms low-angle grain boundaries (LAGBs), which reduces the hindrance to crack propagation, so the mechanical properties of SCHAZ decrease. In addition, the texture analysis found that UCHAZ has the highest 〈001〉//RD orientation volume fraction, indicating that UCHAZ is most prone to rapid expansion of brittle cracks on the {001} cleavage plane, so the toughness of UCHAZ is reduced. SCHAZ has the highest {001}〈110〉 texture volume fraction and the lowest proportion of high-angle grain boundaries (HAGB), indicating that the deformed grain structure with the {001} cleavage planes distributed along the LAGB after welding heat tempering is the main reasons for the delamination of SCHAZ.

Surface treatment by crystalline Co-P coating with ultra-thin CoTe2 layer for improved electrical and mechanical properties of the n-type Bi2Te3/Sn TEG electrode

Bismuth telluride-based thermoelectric generators (TEG) were widely used in the clean recovery of waste heat, but frequent failure problems at the hot-end electrode interface limited the reliable service of TEGs. Diffusion at the electrode interface between n-type Bi2Te3 and Sn-based solder seriously damaged the performance of the TEGs. In this work, the crystalline Co-4 at.% P coating was deposited to protect the n-type thermoelectric material Bi2Te3. The microstructural characterization proved that the Co-P coating effectively resisted the diffusion of Sn, Bi, Te and Cu atoms, and prevented the generation of brittle intermetallic compounds (IMC) and cracks at the interface. Ultra-thin CoTe2 layer was formed between Co-P and Bi2Te3, much thinner than the brittle Ni-Te layer reported in the literatures. It not only showed that a good metallurgical bond was formed between Co-P and Bi2Te3, but also implied the Co-P only consumed little thermoelectric elements. After the 150-hour aging test at 423 K, the shear strength of the electrode joints did not decrease, and the power generation sustainability of thermoelectric pillars was significantly improved compared with uncoated pillars. Overall, the crystalline Co-P coating would be an excellent candidate to protect the n-type Bi2Te3 pillars of the TEGs.

The Properties and Microstructure of Na2CO3 and Al-10Sr Alloy Hybrid Modified LM6 Using Ladle Metallurgy Method.

In this work, Al-10Sr alloy and Na2CO3 were added to LM6 (reference alloy) as hybrid modifiers through ladle metallurgy. The microstructure enhancement was analyzed using an optical microscope (OM). The results were further confirmed with Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) spectroscopy. The results showed that Na2CO3 and Al-10Sr alloy successfully hybrid modified the sharp needle-like eutectic Si into fibrous eutectic Si. Soft primary Al dendrites were also discovered after the hybrid modification. The formation of β-Fe flakes was suppressed, and α-Fe sludge was transformed into Chinese script morphology. A 2.13% density reduction was recorded. A hardness test was also performed to investigate the mechanical improvement of the hybrid-modified LM6. 2.3% of hardness reduction was recorded in the hybrid-modified LM6 through ladle metallurgy. Brittle cracks were not observed, while ductile pile-ups were the main features that appeared on the indentations of hybrid-modified LM6, indicating a brittle to ductile transformation after hybrid modification of LM6 by Na2CO3 and Al-10Sr alloy through ladle metallurgy.

Effects of Stress State, Crack—γ/γ′ Phase Interface Relative Locations and Orientations on the Deformation and Crack Propagation Behaviors of the Ni-Based Superalloy—A Molecular Dynamics Study

In this study, we systematically investigate the influence of stress states, relative locations, and orientations of crack—γ/γ′ phase interfaces on the deformation and crack propagation behaviors of the Ni-based superalloy through molecular dynamics simulations. The stress state with high stress triaxiality will impede the plastic deformation process of the system, thereby promoting brittle crack propagation within the system. But the stress state of low stress triaxiality results in obvious plastic deformation and plastic crack propagation behaviors of the system. The deformation system with cracks located in both the γ and γ′ phase exhibits the slowest growth rate, regardless of applied stress states. Additionally, the deformation process demonstrates prominent plastic behavior. For the deformation system with cracks perpendicular to the γ/γ′ phase interface, the γ/γ′ phase interface will hinder the crack propagation. Our research provides interesting observations on deformation and crack propagation behaviors at an atomic level and at a nano-scale which are important for understanding deformation and fracture behaviors at a macroscopic scale for the Ni-based superalloy.

Cold resistance of steel beam prestressed by wall drawing

Introduction. The purpose of the article is a generalized analysis of existing methods for determining of structural steel elements behaviour in extreme conditions of subzero temperatures and their use to assess the cold resistance of steel beams prestressed by drawing of a thin wall. Subject of study is structural steel. Object of study is bimetallic steel beam prestressed without rods.Materials and methods. The study is based on the mechanics of deformable solid bodies, studies of the mechanical characteristics of steel and its behaviour at considerable subzero temperatures, taking into account stress concentrators and the probability of brittle cracks in the beam elements.Results. The impact strength analysis of steels C440 and C245 used in the flange plates and wall of prestressed beam was carried out. It is found that during the structure operation in the temperature range from minus 45°C to minus 55°C, cold resistance of the beam elements is ensured. It is proved that actual normal stresses in the extreme fibers of the prestressed beam web section are lower than the allowable stresses during plastic deformation of the wall material and, according to the theory of M. Huber, R. Mises and H. Hencky, the probability of brittle cracks in stress concentrators zone is low. It is found that the absence of stiffeners along the beam wall reduces plastic deformations caused by welding, reduces the number of extra elements in the structure and increases the material’s cold resistance.Conclusions. The high stability of prestressed beam wall enables designing it quite thin and increasing its cold resistance. The stressed state of the structure, reduction of its weight, thinning of wall, absence of welding stress concentrators, and reduction of the number of extra elements in the beam testify to the cold resistance of the material of the beam pre-stressed by wall drawing.

Small punch creep test reveals the differences of high-temperature creep behaviours for laser powder bed fusion and Rolled Inconel 718 alloys

The laser powder bed fusion (LPBF) additive super alloy is with the manufacturing advantages in high temperature equipment, but their creep behaviour especially for the effective heat treatment is not well understood. In this paper, small punch creep test (SPCT) is used to compare the creep properties of Inconel 718 fabricated by LPBF and the counterpart processed via rolling, considering different heat treatments. After aging heat treatment, both creep deformation and life of LPBF Inconel 718 are much lower than those of rolled nickel-base alloy. In contrast, after solution and aging heat treatment, the creep deformation capacity and life of LPBF Inconel 718 are significantly improved, and the difference of creep resistance between them is greatly reduced. Based on the Chakrabarty membrane stretching model, the equivalent creep strain and equivalent creep stress are estimated. The equivalent creep strain-time curve proves that the solution and aging heat treatment effectively improves the creep resistance of LPBF Inconel 718. Then, based on Norton creep model, Larson Miller model and Monkman Grant model, the creep life equations of LPBF Inconel 718 and Rolled Inconel 718 under two heat treatment conditions are obtained. Finally, the fracture mechanism of Rolled Inconel 718 under aging heat treatment is the creep induced brittle intergranular cracking, while LPBF Inconel 718 is dominated by the creep induced layered brittle cracking with serrated propagation along columnar grains. After solution and aging heat treatment, intergranular brittle cracking caused by microcracks at grain boundaries occurs in Rolled Inconel 718, accompanied by the appearance of creep micro-voids. In comparison, the fracture mode in LPBF Inconel 718 is the zigzag cracking along columnar grain with the elongation and stagger of long columnar grains.

A robust interface finite element formulation for modeling brittle material failure problems

AbstractFailure of many brittle materials and structures can be modeled using interface‐oriented finite elements combined with intrinsic cohesive zone models. The discontinuous Galerkin (DG) finite element method provides an innovative framework for modeling brittle crack propagation with zero‐thickness interface elements, which can accommodate extrinsic cohesive laws to avoid the artificial compliance required in intrinsic cohesive models. However, robust formulations and implementations of DG methods are critical in alleviating the well‐known convergence issues for both crack nucleation and propagation with reduced instability. This paper presents a robust interface element formulation by modifying the incomplete interior penalty Galerkin (IIPG) method, which successfully avoids the initial element interface penetration across elements that occurs prior to crack nucleation, and thereby greatly reduces the instability issue as cracks open. We further verified and validated our implementation by using a bar tension test and a beam fracturing benchmark. The robustness of our proposed interface element method was demonstrated by a micromechanics fiber/matrix debonding problem with 64 fibers embedded in a bulk matrix.

Enhancing durability of ASTM A416 prestressed steel wires against hydrogen embrittlement

In the face of aggressive environment, cathodic protection shows promise as a solution to reducing the risk associated with corrosion initiation and propagation of prestressed concrete structures. This can be achieved by applying an impressed current to the system that brings the electrical potential of steel members to such a level where localized corrosion does not occur. However, atomic hydrogen that evolves at negative potential can cause hydrogen embrittlement of ASTM A416 steel wires used in prestressed concrete, leading to system failure without warning. To reduce the risks of brittle failures, nickel–cobalt alloy was applied to steel wires. The corrosion properties of the coated specimens were studied in simulated concrete and corrosive environments. The steel wires were also placed in an aggressive environment to predict the time to failure of the samples due to hydrogen embrittlement. A brittle crack developed in wires tested in the as-received condition, but samples coated with the proposed coating passed the embrittlement test. Nickel–cobalt coated specimens not only showed corrosion properties similar to as-received samples, but also did not fail the embrittlement test.

Testing of Post‐fire Brittleness for Certain Standard Duplex and Lean Duplex Stainless Steel Grades

AbstractThe results of post‐fire brittle cracking susceptibility tests conducted on samples made of selected duplex type stainless steel grades exhibiting austenitic‐ferritic structure, in particular on standard duplex X2CrNiMoN22‐5‐3 steel and on lean duplex X2CrMnNiN21‐5‐1 steel, are presented and widely discussed. General conclusions are based on the force‐displacement graphs obtained by the instrumented Charpy impact test. Prior to the test all samples have been subjected to simulated fire action following the steady‐state heating regime and then cooled down to room temperature. Two heating levels have been considered, namely 600°C and 800°C. The first of these levels has been considered as to low, while the second as sufficiently high, to induce in the considered steel structural changes of permanent character. For comparison, two groups of samples have been tested. Samples belonging to the first group have been heated for one hour (simulation of a short fire), while the ones belonging to the second group have been heated for ten hours (simulation of a long fire). In addition, two alternative cooling modes have been considered, i.e. slow cooling in the muffle furnace and rapid cooling in water mist. The toughness tests on samples made of both steel grades have been conducted at two different temperature values, that is at +20°C to simulate the continued service in summer conditions and at ‐20°C to simulate this future service in winter conditions.

Effects of thermal aging at 873 K on the impact properties of an ODS ferritic steel

This investigation presents the effects of long-term thermal aging on the impact properties of an ODS reduced activation ferritic steel. The ODS ferritic steel, with composition Fe–14Cr–2W–0.4Ti–0.3Y2O3 (wt. %), was manufactured by mechanical alloying, compacted by hot isostatic pressing and hot cross rolled. A 1273 K annealing treatment was applied, followed by thermal aging at 873 K for 2000 h in Ar, to evaluate the thermal stability of the alloy. Charpy impact testing was performed from 77 to 473 K to investigate the mechanical response of the material under dynamic loads. The ductile-to-brittle transition temperature (DBTT) showed a slight increase with values of 255 ± 12 K before aging, and 270 ± 20 K after aging. The aging treatment softened the steep character of the Charpy impact curves inducing a wider transition regime with mixed brittle and ductile fracture mechanisms. This behavior was confirmed by the analysis of Force vs. Displacement Charpy curves and fractographic observations. Hot cross rolling induced a crack divider geometry and secondary cracks formation by delamination. Ductile fracture was less evident after aging due to the redistribution and transformation of Cr-W-rich precipitates along grain boundaries. Electron Backscattered Diffraction highlighted the features of transgranular brittle cracks at temperatures below the DBTT and showed misoriented and deformed regions near the fracture surface at temperatures above the DBTT.

Superior crack propagation inhibitory effectiveness of MWCNT reinforced SBS toward improving oil/gas well cement integrity

The brittleness and low cracking resistance of oil- and gas-well cement threaten its integrity, specially under the high stress concentrations at bottom-hole conditions. Fortunately, the excellent mechanical properties of carbon nanotubes and elastomers motivate researchers to utilize them as versatile candidates that can positively modify the breakage behaviors of cement-based materials. Herein, we investigated the hybridization effects of multi-walled carbon nanotubes (MWCNTs) and styrene–butadiene–styrene (SBS) on the mechanical properties and breakage behaviors of oil- and gas-well cements. MWCNTs and SBS were synthesized and then, characterized with a wide range of techniques, signifying successful syntheses of these two materials. Afterward, SBS was dry mixed with cement powder and then added to the aqueous suspension of MWCNT prepared via sonication method. The mechanical testing (e.g., uniaxial, triaxial, and Brazilian tests), numerical simulation, and imaging analysis showed that incorporation of the SBS into the cement matrix promoted the ductility and macro-scale cracking resistance. The introduction of MWCNTs improved the cohesion, micro-scale cracking resistance, and strength properties of the cement matrix. Thereupon, the hybridization of 0.075 wt% of MWCNT and 9 wt% of SBS endowed great mechanical behavior and cracking resistance to the conventional oil-well cement in both micro and macro structures. These specifications can maintain cement’s durability under the critical thermal and mechanical stress concentrations at various bottom hole conditions. This improvement contains the increasing of strain energy, tensile strength, cohesion, and Poisson’s ratio by 219.27%, 141.17%, 750% and 100%, respectively and reducing the elastic modulus by 41.67%. Fourier Transform Infrared Spectroscopy (FTIR) analysis exhibited that these enhancements can be attributed to favorable interactions between MWCNT and SBS in the cement matrix.

Oxygen-induced brittle cracking and low steady stress in Mo10Nb alloy during hot deformation

Mo10Nb alloy is susceptible to brittle cracking during hot deformation due to a small amount of oxygen. In order to find out the mechanism of oxygen-induced cracking and low steady stress, here we investigate the influence of oxygen on the microstructure and hot deformation of Mo10Nb. Results show that the high chemical affinity with Nb makes the O atoms tend to dissolve inside the grains of Mo10Nb, instead of the segregation at grain boundaries of Mo. The steady stress of Mo10Nb is decreased by the interstitial oxygen during hot deformation, which increases the diffusivity of the alloy at high temperature. The O element induces the low cleavage energy and dislocation pile-up, and thus causes the transgranular embrittlement in Mo10Nb during hot deformation. Our investigation is enlightening to better understand the oxygen-induced embrittlement of Mo10Nb alloy.

Monotonical mechanical behavior of thermo-pressure-activated geopolymeric composites in the indirect tensile test using digital image correlation

There is an increasing interest in alternatives to Ordinary Portland Cement (OPC) for plug and abandonment of oil wells, aiming to obtain more reliable and durable well barriers, with reduced CO2 footprint. Geopolymers can have lower permeability and higher chemical resistance to downhole fluids, compared to OPC-based systems. However, there are concerns about their mechanical behavior, in particular their brittle cracking in tension, which may lead to continuous flow paths for escape of fluids. Fibers can improve this behavior by arresting the growth of cracks, reducing their width, and distributing the strain over a larger area. This work aims to study the tensile behavior of a neat metakaolin-based geopolymer system formulated for well applications, before and after addition of 2%v./v. polypropylene fiber or 2%v./v. wollastonite. The indirect tensile test (ITS) was performed in 11.3 mm diameter cylindrical samples cured under high pressure to minimize macroscopic defects. We used digital image correlation (DIC) to monitor the samples at the millimeter scale, aiming to quantify the efficiency of fibers as crack arrestors. We demonstrated a procedure to obtain reliable and quantitative strain and stress fields for the ITS using DIC, enabling the investigation of local stress heterogeneity. First, a penalized spline-based smoothing scheme is used to compensate random errors and to regularize the strain field. Then, two different approaches are used to determine the average elastic properties and calculate the stress field. A three-dimensional finite element model was used to compare the theoretical strain distribution in the sample to the observable strains at the surface. The experimental results were closer to the simulation than to the analytical solution, which is more representative of the behavior inside the specimen. Hot spots of stress concentration were analyzed to obtain the monotonic stress-strain behavior of the material until failure, showing that local stresses were 33% larger that the macroscopic strength measured in the ITS. The neat geopolymer had higher stiffness and tensile strength, but the samples displayed surface delamination in compression, near the force application points. Wollastonite prevented this superficial phenomenon, but the samples had lower tensile strength. Polypropylene, on the other hand, was very effective in arresting crack opening, allowing significant post-peak deformation. These polypropylene-reinforced geopolymer systems are more suitable for downhole applications, since they can withstand higher strains before the formation of continuous cracks and subsequent loss of hydraulic isolation. The methodology proposed in this paper enabled us to observe and quantify the performance of the reinforcement.