Compressive Failure Load Research Articles

Investigation of compressive strength of primitive geometries printed through the fused deposition modeling technique with different path patterns

Fused Deposition Modeling (FDM) is a material-extrusion-based technique used primarily for rapid prototyping and sometimes for an actual servicing part. In the FDM technique, input parent materials are commercial polymers. FDM also has some manufacturing parameters, and the raster pattern significantly affects the mechanical performance of the FDM products. Due to its intrinsic nature, Acrylonitrile Butadiene Styrene (ABS) is widely used in many industries, such as automobiles, medicine, etc. Producing the primitive geometry and selecting the proper infill pattern is challenging. Therefore, the current research paper investigates the effects of various infill patterns on the compressive performance of the three geometries (sphere, 3-side, and 4-side pyramids) printed through the FDM technique out of ABS material. The compressive experiments were conducted on the printed samples and load-displacement curves were evaluated. The results reveal that the concentrate path pattern in the sphere samples has the highest compressive failure load (40127 N). Also, the compressive failure loads in the 3-side and 4-side pyramids fabricated with a 45°/−45° raster pattern are 30444 N and 44396 N, respectively. Finally, comprehensive discussions about the obtained results are stated.

Biomechanical comparison of femoral neck anti-rotation and support system versus femoral neck system for unstable pauwels III femoral neck fractures

BackgroundThe optimal treatment method for managing unstable Pauwels III femoral neck fractures remains undetermined. The aim of this study was to compare the biomechanical properties of two types of Femoral Neck Anti-rotation and Support System (FNAS) and a Femoral Neck System (FNS) in unstable Pauwels III femoral neck fractures.MethodsEighteen synthetic femoral models were implanted with one of three fixation devices: FNS, FNAS I, or FNAS II. An unstable Pauwels III (OTA/AO 31-B2.3) femoral neck fracture was simulated using a custom-made needle and osteotomy guide. Torsion and axial compression loading tests were conducted, and the torque, torsion angle, load to failure, displacement, and stiffness values were recorded.ResultsFNAS II exhibited significantly higher torsional stiffness (0.67 ± 0.10 Nm/°) compared to FNAS I (0.52 ± 0.07 Nm/°, P = 0.01) and FNS (0.54 ± 0.07 Nm/°, P = 0.005). FNS demonstrated significantly greater mean axial stiffness (239.24 ± 11.38 N/mm) than both FNAS I (179.33 ± 31.11 N/mm, P = 0.005) and FNAS II (190.07 ± 34.11 N/mm, P = 0.022). FNAS I (302.37 ± 33.88 N/mm, P = 0.001) and FNAS II (319.59 ± 50.10 N/mm, P < 0.001) showed significantly higher initial axial stiffness compared to FNS (197.08 ± 33.68 N/mm). Both FNAS I and II improved resistance to deforming forces at a load level before approximately 1000 N, which is sufficient to withstand the load from most daily life activities. No significant differences were observed in compression failure load among the groups. The failure patterns at the point of failure included the pull-out of the distal locking screw and reverse oblique intertrochanteric femur fracture for FNS, while for FNAS I and II, the failures were characterized by a cleft on the calcar femorale and a decrease in the load–displacement curve.ConclusionsIn unstable Pauwels III femoral neck fractures, the FNAS II enhances stability and is easier to manage for reoperation. The results of the current study support the potential of FNAS II as an alternative option for treating unstable Pauwels III femoral neck fractures in young individuals.

Experimental study on compression properties of composite aluminum honeycomb sandwich structures

AbstractThe mechanical properties of the carbon fiber and glass fiber composite honeycomb sandwich structure were studied through compression experiments. The influence of different aluminum honeycomb edge lengths, upper and lower panel thickness, aluminum honeycomb thickness, and loading speed on the compression failure load of carbon fiber composite laminates sandwich structure is analyzed. The influence of different aluminum honeycomb edge lengths and thicknesses on the compression failure load of glass fiber composite laminates sandwich structure was studied. The results show that the thickness of the panel has a significant effect on the failure load of the carbon fiber composite laminate sandwich structure, and the loading speed has a significant effect on the failure load of the carbon fiber composite laminate sandwich structure. The greater the loading speed, the greater the value of the failure load. The edge length and thickness of the aluminum honeycomb have a certain effect on the damage load of the carbon fiber composite laminates sandwich structure, but the influence on the mechanical properties of the glass fiber composite laminates sandwich structure is much greater.Highlights The compression performance of composite sandwich structures was experimentally studied. The influence of composite panel thickness was studied. The influence of aluminum honeycomb edge length and thickness was studied. The influence of loading speed was studied.

Study on the mechanical properties and optimization methods of high-strength high-modulus carbon fibre composite with the cap structure

The application of high-strength, high-modulus carbon fiber with excellent properties such as high modulus, conductivity, and thermal conductivity has been increasingly widespread in aerospace flight, deep space exploration, and near-space vehicles. In recent years, with the continuous enhancement of functional requirements for products in these domains, there is a growing need to optimize the typical structure of such carbon fibers to enhance their load-bearing capacity. Therefore, in this study, we first conducted basic mechanical performance tests on specimens of T1100/5405 composite materials to obtain fundamental mechanical performance parameters of the material. Subsequently, compression and bending performance tests were performed on a typical hat-shaped structure to understand its actual load-bearing capacity and failure modes. The results indicate that the compressive failure load and bending failure load of the hat-shaped structure are 474.44 kN and 27.365 kN, respectively. Additionally, by combining the fundamental mechanical performance parameters of the composite material, the mechanical performance of the hat-shaped structure was simulated and verified using finite element analysis software, with the model validated using experimental data. Finally, layering parameters of the established finite element model were optimized, resulting in an increase of the structure’s load-bearing capacity under compression and bending loads to 662.629 kN and 31.9059 kN, respectively. In conclusion, the optimization approach presented in this paper for the T1100/5405 composite material’s hat-shaped structure is efficient. It yields noticeable improvements, significantly enhancing the load-bearing capacity of the typical structure in various application scenarios.

Resistance of natural stone masonry wallettes under centred and eccentric compressive loading: Experimental and numerical approaches

Masonry walls are typically subjected to eccentric compressive loadings in common buildings. However, the design of walls towards this type of solicitation remains very empirical, often leading to oversizing the structure. This is especially true for natural stone masonry, for which experimental data are quite scarce. This paper presents an experimental campaign on 15 natural stone masonry wallettes subjected to centred and eccentric compression until failure. Different values of the eccentricity of the load, ranging from h/12 to h/4 (where h is the thickness of the wallette) were investigated, highlighting the noticeable effect of such a value on the compressive failure load. During the tests, the displacements were recorded by a Digital Image Correlation system, providing insights into the different failure mechanisms that depend on the value of the eccentricity. The so-obtained experimental failure loads are then compared to the predictions of Eurocode 6. Finally, a finite-element yield-design analysis of these tests is proposed which shows that this modelling framework is suitable to find the ultimate bearing capacity of a masonry wallette.

Printing strategies to fabricate a disk through the fused deposition modeling method

The fused deposition modeling (FDM) technique is widely used in different industries due to its low cost and ability to produce complex geometries from polymers. In this technique, some manufacturing parameters are essential because of their effects on the mechanical performance of the final fabricated part. The current study investigated the impact of path strategy and printing speed, two key manufacturing factors, on the mechanical performance of printed disks. Six types of path strategies of rasters corresponding to the loading direction, namely unidirectional-vertical, unidirectional-horizontal, unidirectional-45, cross, cross-45, and concentrate, were used for printing some disks, and compressive tests were done on them. The results showed that these path strategies’ average compressive failure loads were 2955, 4957, 2342, 4640, 3971, and 5893 N, respectively. The lower compressive strength of the unidirectional path pattern was due to the weak zones that were located between the printed layers and rasters. Besides, three printing speeds of 40, 60, and 80 mm/s were considered to fabricate the disks with a concentrate path pattern, and compressive experiments were performed. The results showed that the 40 mm/s printing speed conducted a compressive failure load of 4544 N, while 60 and 80 mm/s resulted in 3008 and 2828 N, respectively. Finally, inter-layer strength as a major factor in controlling the compressive strength of the disks was comprehensively discussed.

Enhancing the mechanical performance of notched glass/epoxy composite laminates via hybridisation with thermoplastic fibres

This study examines empirically and theoretically the open-hole tension and compression characteristics of thermoset composites using hybrid glass/polypropylene and glass/innegra yarns. The Abaqus software, finite element analysis (FEA) has been adopted to predict the tensile and compressive failure loads and damage failure modes for un- and notched samples under tensile and compressive strength tests. The commingling technique was used to create hybrid yarns, which were then transformed into non-crimp preforms before the infusion procedure. It was noticed that the inclusion of thermoplastic polypropylene (PP) and innegra fibres increased the ductility of yarns and composites. Densities of hybrid composites were also reduced by up to 20% when compared to pure glass/epoxy composites. Tensile and open-hole tensile (OHT) test results revealed that hybrid composites are less notch sensitive than glass/epoxy composites due to enhanced composite ductility. For glass composites, having holes resulted in a 41% decrease in tensile strength, compared to reductions of only 25% and 26% for PP and innegra fibre composites, respectively. Further, compression and open-hole compression (OHC) tests presented similar results with OHT tests whilst compressive strength reduction was lower for hybrid composites (10% and 11%) compared to glass/epoxy (28%) ones. The results of the numerical simulation for damage failure modes and tensile and compressive failure loads for un-notch and notched composite laminates are consistent with the experimental findings both qualitatively and quantitatively.

Experimental study on the mechanical properties of three‐dimensional braided composite circular tubes with preembedded licker‐in

AbstractThis study investigates the tensile and compression properties of three‐dimensional five‐direction (3D5D) braided composite circular tubes with preembedded titanium alloy licker‐ins. The influence of the braided angle, braided thickness, and braided configuration on the bearing capacity is analyzed, and the microdamage morphology and failure mechanism of the tube structure are examined using scanning electron microscopy. Results show that the 3D5D braided tube has a larger tensile failure load than the 3D full five‐direction braided tube of the same outer diameter. In circular tubes of the same braided configuration and outer diameter, the compression failure load increases with the wall thickness, and the C‐ø30t3 circular tube achieves the maximum compression failure load. The damage morphology is characterized by the pulling‐off failure of the licker‐in joint. The T‐ø30t2.5 and T‐ø25t3 circular tubes achieve a large failure load, with an average tensile load of over 120 kN. The failure morphology is characterized by the cracking of the fiber at the end of the tube after the licker‐in joint has been pulled off. The average tensile failure load of the T‐ø30t3 circular tubes is over 105 kN, and the failure morphology reveals a broken licker‐in joint, indicating design deficiencies that require further optimization. The findings of this paper can provide an important scientific basis for the lightweight and high‐strength connection design for 3D braided composites in near‐space aerostats and their flight applications.

Enhancing the quasi-static strength of prosthetic socket made from composite laminates via hybridisation: Experimental and numerical study

This study aims to develop composite laminates for the manufacture of prosthesis socket with enhanced mechanical performance. Layered hybridisation of fabrics (i.e. glass, carbon, and Kevlar fabrics) is used to manufacture hybrid composite laminates by resin infusion via vacuum bagging method. The response of these materials to compression loading is investigated by using compression-loading testes and the load-bearing ability was examined by tensile strength tests. Moreover, finite element analysis has been carried out by using the Abaqus software to predict the compressive failure load and damage failure modes for all sockets samples. Experimental results revealed that the hybrid laminates exhibited more stability and higher absorbing energy compared to non-hybrid laminates during compressive loading tests. Furthermore, the hybridisation of fabrics layers can play key role for improving the tensile strength properties of hybrid composite laminates compared to composite laminates without hybridisation. The numerical simulation results of compressive failure load and damage failure modes are in accordance with experimental results qualitatively as well as quantitatively.

Compressive strength prediction of composite lattice structure using compression test results of subelement specimens

A cylindrical structure used in a space launch vehicle should endure the compressive load and it must satisfy the requirement of compressive strength. For the light-weight of the structure and improving the performance of launch vehicle, a cylindrical structure reinforced by composite lattice can be used. Therefore, a compressive strength prediction technique of the cylindrical composite lattice structure is required. In this paper, the failure criterion was proposed using the compression test of a composite lattice subelement and a simple finite element analysis for the subelement. The failure criterion was introduced using the effect of the out-of-plane and in-plane bending deformation of the rib constituting the grid of structure on the compressive strength. The subelement specimen was prepared from two different structures and the compression test was performed using several fixture jigs which can generate various deformation of the specimen. The test results and finite element model were used to examine the effect of out-of-plane and in-plane bending deformation of the rib on the compressive strength and the failure criterion which can predict the compressive strength was derived using the relationships between each parameter. The compressive failure load of the cylindrical composite lattice structure was predicted by using the proposed method and the validity and accuracy of this method were verified through a comparison of the predicted results with the test results. It was possible to predict the compressive strength within a 5% error of the experimental result.

Investigation of Compressive Strength of Slag-based Geopolymer Concrete Incorporated with Palm Oil Fuel Ash

The paper investigated the compressive strength of ground granulated blast furnace slag-based geopolymer concrete incorporated with palm oil fuel ash compared to portland limestone cement concrete. An appropriate geopolymer mix design was first determined. This mix entailed fine aggregates: coarse aggregates: cementitious material: liquid ratio of 2: 2.5: 1: 0.5, respectively, with 100% replacement of portland cement with ground granulated blast furnace slag (GGBS) incorporated with palm oil fuel ash (POFA). An alkaline solution was used in place of water containing sodium hydroxide and sodium silicate. Following this design, five geopolymer mixes were prepared, each of varying POFA-GGBS ratios of 0:100, 25:75, 50:50, 75:25, and 100:0, and a 14M alkaline solution was used. In addition, a control mix was determined, comprising 100% portland limestone cement (PLC) as the cementitious material and 100% water. Three cubic samples were casted for each geopolymer mix with the control mix, and then the geopolymer mixes were thermally cured for 24 hours. The compressive strength test was conducted on the test samples after ambient curing of 7 days and 28 days, and values for compressive strength (MPa) and failure load (KN) were recorded. Through comparative analysis, it was determined that the most efficient geopolymer mix was mix 2 of GGBS: POFA ratio of 75:25 with 14M alkaline solution. Mix 2 achieved the highest compressive strength of 65.41MPa, approximately 21.99% higher than the strength attained by portland cement concrete samples, measured to be 53.62MPa. Thus, geopolymer concrete can achieve greater strength than portland cement concrete. Keywords: Alkaline solution, Geopolymer concrete, cementitious material, ground granulated blast furnace slag, compressive strength, palm oil fuel ash

On damage behavior and stability of composite T-shaped stiffened panels under compression after impact considering impact locations

Impact locations play a critical role in determining the residual performance of the composite stiffened panel, since the local damage behavior at different locations is not identical. The objective of this paper is to systematically investigate the influence of impact locations on damage behavior, stability and residual compression strength of T-shaped stiffened CFRP panels. Low-velocity impact tests are carried out by impacting at the skin center or the flange tip. The damage patterns and post-buckling behavior are monitored by ultrasonic C-scan and digital image correlation. An effective computational framework with explicit formulations considering complicated damage mechanisms is proposed to investigate the details of damage behavior. The skin center impact causes severe fiber breakage and matrix squeezing, while the flange tip impact induces complex damage patterns including ply splitting, fiber breakage, matrix cracks, as well as extensive skin–rib interfacial delamination. Compression after impact results indicate that impact damage at the skin center has little effect on the residual performance of the structure, and the compression failure load is only reduced by 2.02%, from 276.8 kN to 271.2 kN. However, impact damage at the flange tip weakens the supporting effect of the stiffener, leading to early buckling of the local skin. The propagation of the interfacial delamination at the damaged flange tip directly triggers the premature compression failure, resulting in an 18.79% decrease in the failure load, 224.8 kN. Numerical predictions correlate well with experimental data. The reported results may be useful in structural design and maintenance.

Post-buckling failure analysis of composite stiffened panels considering the mode III fracture

Fully utilizing the post-buckling capacity of stiffened composite panels is important to reduce the weight of aeronautical composite structures. However, owing to the complex post-buckling failure modes and mechanisms, there are no effective analysis methods. This paper explores the impacts of the mode III fracture energy on the damage behavior of the stiffener–skin interface of composite stiffened panels under post-buckling conditions. To characterize the bonding interface damage, an interface damage initiation criterion considering the effects of through-thickness compression on the shear failure was used and combined with the Reeder damage extension criterion, which considers the mode III fracture. The mode III fracture toughness characteristics of the damage evolution of the stiffener–skin interface were obtained using the edge crack torsion (ECT) test method. Moreover, the compressive deformation response, buckling load, buckling modes, failure load, and failure modes of the panel were obtained by a compression test of I-shaped stiffened panels. Based on the aforementioned experimental data and numerical model, the post-buckling behavior of the I-shaped stiffened composite panels with an open cross-section stiffener was studied. It was found that the mode III fracture energy caused by the longitudinal shear stress τ31 played a major role in the stiffener–skin interface damage extension of the stiffened panels. Therefore, the mode III fracture behavior should not be ignored in the post-buckling analysis. The numerical analysis method developed can accurately predict the damage initiation and evolution processes of the composite panel interface. The method can be effectively used for post-buckling analysis of aeronautical composite panels.

Study of matrix modifications by nano-clay on the mechanical properties of AA3003 honeycomb sandwich panels

Face/core debonding is one of the crucial problems of composite sandwich panels which consist of AA3003 aluminium honeycomb and glass fiber reinforced polymer face sheets. The panel was prepared by a hand-lay process at different nano-clay weight addition of 0%, 2%, 4%, and 6% with the objective of improving face/core adhesion. Interface bonding between face sheets and honeycomb core composite sandwiches and their mechanical behavior were investigated under in-plane compression and bending load. The flexural property of sandwich panels due to the influence of variation in strain rate is further determined. The morphologies of fractured samples were investigated by scanning electron microscope (SEM). The results revealed a significant improvement in mechanical characteristics when nano-clay was loaded to the composites at a concentration from 2 to 4 wt%, and the in-plane compression and flexural failure load values increased by 45% and 81%, respectively, when compared to a pristine sample. It was observed that increasing strain rate led to the increase in failure load of the sandwich panel. SEM images of fractured surfaces showed residual aluminium honeycomb was present in the face sheet, which indicates better adhesion between aluminium honeycomb core and face sheets.

Failure modes of bonded wrapped composite joints for steel circular hollow sections in ultimate load experiments

The concept of an innovative bonded joining technology where welding is not required is presented as an alternative to traditional welded connection for steel circular hollow section (CHS). Wrapped composite joints have potential to greatly improve fatigue endurance when applied in multi-membered truss structures, e.g. offshore jackets for wind turbines. This paper focuses on characterization of resistance and understanding of failure modes of wrapped composite joints in static experiments, as the prerequisite for harvesting its potential for high fatigue endurance. Wrapped composite joints at two scales and with two different angles of X-joint geometry are made with GFRP composite material wrapped around steel sections without welding, and tested in 3 monotonic loading cases, tensile, compression and in-plane bending, until failure. Counterpart welded joints are tested at the smaller scale for stiffness, elastic limit and ultimate load comparisons. Two general failure modes of wrapped composite joints, debonding and fracture of the composite material are identified and quantified by surface strain measurements through 3D digital image correlation (DIC) technique. Testing results indicate that wrapped composite joints have 30% to 56% larger stiffness and 3% to 68% larger ultimate load compared to welded counterparts. Debonding and final pull-out of steel brace member from the composite wrap is predominant failure mode in tensile experiments at both scales while cracking of the composite material is the governing failure mode in the bending experiment. In tensile, compressive and bending experiments failure load of wrapped composite joints exceeds the yield resistance of the steel CHS indicating opportunity to optimize the composite wrapping thickness and length.

Influence of resin removal treatments on the surface topography and strength of de-bonded lithium disilicate ceramic.

This study aims to assess the influence of resin removal treatment regimes on the surface topography and compressive strength of de-bonded ceramic surfaces. Sixty-five lithium disilicate ceramic (LDC) discs were prepared, cleaned, and polished with carbide paper. All samples were etched using 9.6% hydrofluoric acid (HFA). Fifteen samples were taken as positive controls; the remaining 50 samples were subjected to the process of silanization. Resin build-up using dual-cure cement was performed incrementally and light cured. Based on different methods of resin cleaning from de-bonded LDC, the samples were divided into five groups, n=10 each: group 1 (no treatment), group 2 (slow-speed diamond bur), group 3 (1 min heat treatment), Group 4 (6 min heat treatment), and group 5 (sandblasting with Al2O3). Following resin removal, LDC samples were tested under compressive failure load in a universal testing machine. Five disc specimens from each group were sputter coated with gold for scanning electron microscopy (SEM). Analysis of variance (ANOVA) and Tukey's post hoc test was used for descriptive statistics. Level of significance was established at p<0.05. The highest compressive strength with significant difference among all experimental groups was found in group 5 (321.54 ± 13.25 MPa) (p<0.05). The lowest compressive strength values, presenting significant difference compared with all other groups, were displayed in group 1 (158.57 ± 5.22 MPa) (p<0.05). Compressive strength among group 2 (231.54 ± 15.55 MPa), group 3 (237.81 ± 10.81 MPa), and group 4 (255.53 ± 8.95 MPa) specimens was statistically comparable (p>0.05). On SEM, heat-treated specimens confirmed coarser granules, with mild porosities and roughening, whereas sandblasted specimens exhibited consistent evenness with moderate porosity and loss of glazed surface. De-bonded LDC surface, treated with heat treatment and sandblasting procedures, exhibited removal of residual resin and significantly high compressive strength compared with non-cleansed ceramic surface.

Numerical study on fiber waviness defect and sensitivity analysis of the parameters

The presence of fiber waviness defects is well-known to reduce the compressive strength. A FE model was established and the results of failure load and mode were compared with the test results to demonstrate the validity and accuracy. The influence of two parameters L and offset Angle θ of fiber waviness defect was studied. The simulation results show that the compression failure load increases with the increasing of L at constant A/H for convex and concave fiber fold by 33.0% and 20.1% respectively, but there is no significant effect on the failure load with θ within 5%.

Repairing sharp delamination cracks in CFRP through capillary action of acetone-diluted resin solution

Shape delamination cracks in carbon fiber composites were successfully repaired utilizing the capillary action of acetone-diluted resin solutions (without hardener). Resin pre-coating (RPC) solutions with 5, 10, 15, 30 and 45 wt% resin were tested and their repair effectiveness were compared. Resin curing inside narrow delamination cracks was achieved by applying the normal resin/hardener mixture at the open delamination edge so the hardening process could take place inside the resin-filled delamination cracks with time. Compressive tests were performed after 7, 21 and 42 days of repair to study the influence of curing period. The edge delamination was introduced through light impact at the edge of CFRPs panels. Compressive failure loads after repair showed that the 30 wt% of RPC solution yielded the most favorable repair result for the 7-day curing time. With 21- and 42-day curing times, even the least favorable repair condition of 5 wt% of the RPC solution produced significantly improved repair results. X-ray scanning was used to reveal the internal delamination before and after repair.

Behavior of ECC columns confined using steel wire mesh under axial loading

Engineered Cementitious Composite (ECC) is a high-efficiency composite material that possesses work-hardening behavior in addition to its multiple-cracking specifications. It overcomes toughness and cracking problems caused by concrete brittleness due to the tight crack width it has. This paper studies experimentally the behavior of axially loaded reinforced ECC columns, with additional internal confinement using Steel Wire Mesh (SWM), to enhance ultimate capacity, durability, the crack pattern, and reduce the brittleness of traditional columns. Sixteen circular columns, one Normal Concrete (NC) specimen, and fifteen ECC specimens were subjected to axial compression up to failure. The main parameters of the study were the volume fraction of the polypropylene fibers (1%, 1.5%, and 2%), SWM arrangements, and number of SWM layers. Experimental findings demonstrated that ECC specimens exhibited better performance compared to NC specimen concerning crack control efficiency, load capacity, and ductility. As the ECC specimens presented very thin cracks and higher ultimate load in the range of 65.57%–107.39%, with greater ductility in the range of 0.87%–17.39% compared to the NC specimen. Additionally, ECC columns with 1.5% of polypropylene fiber, showed the highest compressive strength, superior durability, and maximum failure load. Moreover, the SWM contributed enhancing the capacity of ECC columns due to its confinement effectiveness. Besides, the full confinement scheme of SWM around the core of ECC columns, regardless of the fiber ratio, exhibited the maximum strength while maintaining appropriate flexibility. Moreover, the ultimate load increased by 16.82%, 13.22%, and 12.86% for fully confined ECC specimens containing PP fibers ratio of 1%, 1.5%, and 2%, respectively compared to their control specimens.

Experimental and Numerical Study on the Compressive Failure of Composite Laminates with Fiber Waviness Defects.

Fiber waviness defects are found in the inner surface of the hat-shaped stringers manufactured by a process system. In order to establish the acceptance criterion for the stringers with the fiber waviness defects, experimental testing and numerical simulation were carried out in this study. Specially induced fiber waviness defects of four pre-defined severity levels were manufactured and tested. A maximum of a 58.1% drop in compressive failure load is observed for the most severe level in the experimental results. A finite element model with progressive damage method and cohesive zone technique was developed to simulate the failure process and the impact of fiber waviness defects. The numerical simulation results of compressive failure load have a good agreement with experimental results qualitatively and quantitatively. In addition, two simple parameters, i.e., aspect ratio A/H and the number of plies with fiber waviness, are proposed to characterize the influence of the fiber waviness on the compressive failure load for the purpose of fast engineering quality checks.