Increasing Thickness Ratio Research Articles

Effect of thickness ratio on microstructure evolution and coordinated behavior of Mg/Al composite plates in one-pass asymmetric rolling with differential temperature rolls

To explore how varying matrix thicknesses influence interfacial morphology, microstructure, and mechanical properties of Mg/Al composite plates, this study prepared composite plates with distinct thickness ratios using an asymmetric rolling process featuring differential temperature rolls. The findings indicate that the Mg alloy largely exhibits significant recrystallization and sub-grained, while the Al alloy largely demonstrates a sub-grained characteristic. Notably, there exists a strong positive correlation between bonding strength at the interface and thickness ratio. As the thickness ratio increases, enhanced shear deformation at the interface triggers more slip system initiation, resulting in a gradual reduction of texture intensity in both the Mg and Al layers. Specifically, when the AZ31B/Al6061 thickness ratio reaches 5, the recrystallization level of the Mg layer is relatively elevated, accompanied by a fine and uniform grain size in the Al layer. This situation decreases the likelihood of stress concentration at the interface, which results in exhibiting relatively optimal elongation and bonding strength.

Mechanical behavior and cement sheath damage characteristics of casing pullout based on peridynamics

In petroleum exploration and production, the recovery and replacement of casing are crucial. However, difficulties often arise during casing pullout operations due to the strong bonding strength between the casing and the cement sheath. Currently, there are few researches on casing pullout process, which leads to the fact that casing pullout operations often relies on experience and lacks theoretical support. To comprehend the mechanical behavior, interface shear failure mechanisms of casing pullout process, and to propose rational solutions for practical engineering applications, this study establishes a Peridynamics (PD) numerical model for casing pullout to conduct research and analysis on its process. Based on the characteristics of the cement sheath, a damage model for the cement sheath is proposed in this paper. Additionally, a kernel function is introduced to reflect the variation of long-range forces with the distance between material points, aiming to characterize the changes in the stiffness of bond constant within the horizon of material points. The mechanical responses of the cement sheath and casing at different phases of the casing pullout process are analyzed and characterized. The research results indicate that an increase in the casing-cement sheath thickness ratio promotes the damage at the casing-cement sheath interface, reducing the time required for casing pullout but inhibiting the expansion of cement sheath cracks. As the thickness ratio increases from 0.1 to 0.18, the degree of cement sheath damage decreases from 6.904% to 6.453%. The increase in Young's modulus of the cement sheath is negatively correlated with the time required for casing pullout, positively correlated with the interface failure rate, and it does not exhibit a linear relationship with the degree of cement sheath damage. Within the range of Young's modulus from 4 to 20 GPa, the maximum difference in cement sheath damage degree is 3.715%. In engineering practice, the Young's modulus of well cement and the thickness ratio of casing-cement sheath can be appropriately increased to enhance pullout efficiency.

Pullout behavior of the steel-FRP composite bar with the anchor head made of the grout-filled steel tube

Steel-fiber reinforced polymer composite bars (SFCBs) offer a viable solution to replace steel bars in concrete structures and mitigate their corrosion issues. However, the inflexibility of SFCBs weakens their bond with concrete. This study addressed this gap by employing a steel tube connected to the end of SFCB using grout as its anchor head. Subsequent pullout tests were conducted on SFCBs with and without anchor heads, exploring variables such as SFCB diameter, anchorage length, anchor-head diameter, concrete-cover thickness, and spiral ratio. Various failure modes were observed, including SFCB rupture, and concrete cracking with and without stirrups. Anchor heads significantly enhanced the bearing capacity and bond stiffness of SFCB specimens, notably reducing splitting forces. Augmenting anchorage length and anchor-head diameter improved the bond stiffness of SFCBs in concrete. The anchor-head diameter should not be less than 2.4 times the SFCB diameter. Furthermore, an increase in concrete-cover thickness or spiral ratio notably heightened the concrete’s resistance to cracking. The contribution ratio of bond force increases with the anchorage length and decreases with the slip, SFCB diameter, and anchor-head diameter. A predictive method for determining concrete-cover thickness and spiral ratio was developed to ensure SFCB pullout specimens steer clear of concrete splitting.

Thermal buckling analysis for hybrid and composite laminated plate by using new displacement function

Abstract The analysis of a critical buckling temperature is dependent on the new displacement function field provided in the literature and uses third-order shear deformation theory. The value of the parameter “m,” which determines the new displacement function, closed with the three-dimensional (3D) elasticity results. Thermal critical buckling is analyzed for thick and thin laminated plates by using the Navier solution for symmetric and anti-symmetric cross-ply simply supported boundary conditions. Several design parameters are considered such as extension thermal coefficient ratio (α 1⁄α 2), number of schemes, thickness ratio (a/h), aspect ratio (a/b), and modular ratio (E 1/E 2) when analyzing the dynamic behavior of the critical buckling temperature for different materials, including composite (glass/epoxy) and hybrid (glass/carbon/epoxy), under uniformly distributed temperature load. The accuracy for theoretical results by using Matlab R2019b was checked with other results for different researchers and gave good agreement. Increasing orthotropic ratio and aspect ratio resulted in increasing critical buckling temperature in M1 than M2, whereas increasing thickness ratio, thermal coefficient expansion, and number of layers resulted in decrease in critical buckling temperature in M2 than M1.

In-Plane Dynamic Cushioning Performance of Concave Hexagonal Honeycomb Cores

In order to further study the cushioning performance of concave hexagonal cores (CHCs) and expand their application range, the in-plane finite element model of CHCs is established in this paper. A dynamic cushioning coefficient method was proposed to characterize the cushioning performance of CHCs. The dynamic cushioning coefficient curve and minimum dynamic cushioning coefficient (MDCC) of CHCs with different impact velocities and structural parameters are obtained. The influence rules of structural parameters and impact velocities on the MDCC are analyzed; the deformation mode and transformation empirical formula are also obtained. The results show that when other parameters are constant, the MDCC of CHCs decreases with the increase of impact velocity, increases with the increase of wall thickness and side length ratio, and decreases with the increase of expansion angle. The theoretical analysis is consistent with the finite element results, which further verifies the reliability of the model. This paper provides a solid theoretical basis for the industrial application of the cushioning performance of CHCs and forms a key technical support.

Study on mechanical properties of interbedded rock masses with microcrack based on thermal-mechanical coupling.

The mechanical properties of deep rock masses are significantly influenced by temperature and other factors. The effect of temperature on the strength of deep rock masses will pose a serious challenge to deep resource exploitation and engineering construction. In this paper, the thermal-mechanical coupling calculation model is established by particle flow code (PFC2D) to study the uniaxial compression response of rock masses with microcracks after temperature load. The strength of failure, microcracks, and strain was analyzed. The results show that: (i) When the soft rock thickness ratio Hs/H < 0.5, the displacement caused by the applied temperature is concentrated at the structural plane, and the contact force is concentrated at the end of the initial microcrack. When Hs/H ≥ 0.5, the displacement caused by the applied temperature is concentrated on both sides of the initial microcrack, and the contact force is concentrated in the hard rock area. (ii) The number of microcracks decreases with the increase of soft rock thickness under different working conditions. When the soft rock thickness ratio Hs/H < 0.5, the relationship curve between the number of microcracks and the vertical strain shows two stages of change. When Hs/H ≥ 0.5, the relationship curve between the number of cracks and the vertical strain changes shows three stages of change. (iii) When the soft rock thickness ratio Hs/H < 0.5, the failure strength decreases with the increase of soft rock thickness ratio at T = 100°C and 200°C. When T = 300°C and 400°C, the failure strength decreased first and then increased. When Hs/H ≥ 0.5, the failure strength increases with the increase of soft rock thickness at T = 200°C, 300°C, and 400°C. At T = 100°C, the failure strength decreases with the increase of soft rock thickness.

Protective Effects of Perinatal Resveratrol on Bisphenol A Exposure-Induced Cardiovascular Alterations and Hepatic Steatosis in Adult Offspring Mice: A Histopathological Study

Perinatal bisphenol A (BPA) exposure promotes the risk of cardiovascular diseases in adulthood. Currently, there is a dire need to develop new therapeutic strategies and options to treat the adverse fetal programming consequences of this exposure. The present study explored the protective effects of perinatal resveratrol (Rsv) administration on BPA exposure-induced adverse cardiovascular changes and hepatic steatosis in adult offspring mice. Pregnant apolipoprotein E-deficient mice were exposed to BPA in drinking water (1 μg/mL) or to both BPA (1 μg/mL) and Rsv (oral; 20 mg kg−1 day−1) during the gestation and lactation periods. Tissues from the heart, liver, left kidney, and brachiocephalic artery from adult offspring (20 weeks old) were processed for staining with H and E, Masson’s trichrome, and Verhoeff–van Gieson and subsequent histology analysis. In both female and male mice who received Rsv supplementation, the following changes were observed in the brachiocephalic arterial wall: (a) a reduction in the BPA exposure-induced increased thickness ratio of the tunica intima to tunica media from 1.3 ± 1.1 µm to 0.5 ± 0.37 µm (p = 0.027) and 0.72 ± 0.58 µm to 0.29 ± 0.25 µm (p = 0.038), respectively, (b) a reduction in the number of elastic lamina breaks (p &lt; 0.05), and (c) the prevention of the BPA exposure-induced progression of atherosclerotic lesions. Further, it also reduced the BPA exposure-induced increased left ventricular thickness by 135 µm and 131 µm in female and male offspring, respectively. The BPA exposure-induced hepatic steatosis score was also significantly reduced with Rsv treatment in female offspring mice (p = 0.02). Renal cortical cytoplasmic vacuolation was identified in both BPA and/or Rsv-treated groups. Our findings suggest that Rsv could be a potential protective candidate against perinatal BPA exposure-induced cardiovascular changes and hepatic steatosis.

A semi-analytical model to predict residual stress distribution in thick wall girth weld with narrow gap welding

Benefited by its high efficiency and low cost, the narrow gap welding has been widely used in thick wall pressure equipment. Considering the fact that defects in welded joints inevitable, the safety assessments for welding equipment with residual stress are crucial. However, for the thick-wall equipment using narrow-gap welding, the current safety assessment standards specifying the residual stress distribution are not detailed or missing. In this paper, the through-wall residual stress of thick wall girth welds with narrow gap welding is studied. The stress components (bending stress, membrane stress and self-equilibrating stress) at the evaluation point are obtained by stress decomposition. The effects of the heat input, the wall thickness, the radius thickness ratio and the number of welding passes on residual stress are considered, respectively. The results show that the heat input only affects the distribution of bending stress and membrane stress. The axial and hoop bending stresses decrease with the increase of the wall thickness, and the hoop membrane stress is about 0.75 times material yield strength. With the increase of radius thickness ratio, the bending stress decreases while the hoop membrane stress increases. The stress distribution is fluctuating when the number of welding layers is small, which be expressed by trigonometric function. The distribution model of welding residual stress through the wall thickness is proposed. The stress distribution obtained by the proposed prediction model is in good agreement with the finite element calculation results.

An integrated computational and experimental study of the failure mode in Mg/Al laminated composite under three-point bending

The deformation behavior of hot-roll-bonded Mg/Al laminated metal composites (LMCs) is investigated, focusing on the crack formation around the interface. The material demonstrates a positive strain rate sensitivity mainly arising from the Mg matrix. A diffusion layer was formed at the Mg/Al interface with a serrated morphology during the two-pass rolling process, which consists of the Al3Mg2 and Mg17Al12 phases. The mechanical responses of the LMCs are evaluated using uniaxial tension, interfacial debonding tests (in normal and shear modes), and microstructure characterization techniques, which clarify the interfacial heterogeneity. The fracture constants of the interface were calibrated and incorporated in the finite element models to predict the failure modes of heterogeneous Mg/Al interface under three-point bending. With the increased thickness ratio of the Mg layer, the damage accumulation rate decreases at the interface and increases in the Mg matrix. As a result, the failure mode transferred from interface failure to matrix fracture. The findings of the present work provide new insight into the failure mechanism in laminated metal composites under bending conditions and can provide theoretical guidance for the plastic forming of such materials.

Matching design of thickness ratio to extend the lifespan of double-layered thermal-barrier coatings

The ceramic materials of advanced thermal-barrier coatings (TBCs) must be exposed to high temperatures (over 1200°C) over a long lifespan. To meet this requirement, researchers have recently developed phase-stable ceramic materials. However, most of the newly developed materials have low fracture toughness and are easily cracked. Double-layered TBCs (DL–TBCs) can potentially provide a fast route to engineering applications of ceramic materials. The present paper attempts to extend the lifespan of DL–TBCs by matching the thickness ratio of the top layer to the bottom layer. First, the lifespans of different DL–TBCs with equivalent thermal insulation were determined in an iso-thermal cyclic test. The lifespan increased and then decreased with increasing thickness ratio. The optimized matching design of the thickness ratio (approximately 2:3) more than doubled the lifespan. Subsequently, the failure mechanism of DL–TBCs with different thickness ratios was analyzed through simulations. Varying the thickness ratio changed the lifespan by influencing the cracking driving force. Finally, to optimize the double-layer structures, the structural evolution was characterized under thermal exposure. Sintering-induced stiffening largely increased the cracking driving force, posing a main failure threat. The simulation suggested that lowering the stiffening degree in the top layer can further extend the TBC lifespan.

Theoretical Analysis of Plastic Behavior of Sandwich Beam with Metal Foam under Repeated Impacts

The phenomenon of repeated impacts on engineering structures is very common, especially in naval and ocean engineering. When marine structures are subjected to repeated impact loadings, deformation and damage will accumulate as the impact number increases, resulting in the failure and damage of the structures, even causing serious accidents. Based on the rigid-plastic assumption, a theoretical model is established to analyze the plastic mechanical behavior of metal foam sandwich beams (MFSBs) suffering from repeated impacts, in which the membrane factor method (MFM) is applied to derive analytical solutions for the plastic responses of MFSBs. The theoretical predictions agree well with the results of impact tests and numerical simulations, indicating that the theoretical model is accurate and reliable. In addition, the dynamic responses of MFSBs are analyzed based on the MFM, and the effects of the core strength and the face thickness on the deflection responses are determined. The results show that the dimensionless permanent deflection of MFSBs is sensitive to the core strength ratio and the face thickness ratio, and as the core strength ratio or the face thickness ratio increases, the dimensionless permanent deflection decreases gradually in an exponential form. In addition, the influence of the core strength ratio and face thickness ratio becomes more significant as the impact number increases. The proposed theoretical method can provide a theoretical reference and technical support for the design of metal foam sandwich structures with improved impact resistance under repeated impact loadings.

Deformation Analysis and Reinforcement Effect of Tunnel Pile Excavation of a Subway Station in a Weak Stratum

The underground hole pile excavation method causes a large vertical displacement in a weak stratum, which affects the safety of structures. For the first time, the hole pile excavation method is being used to construct a subway station in South China, and the settlement law of the area is not clear. It is important to clarify the deformation law of the hole pile excavation method in weak strata and the effect achieved by appropriate reinforcement measures. In this paper, by establishing a three-dimensional finite element model of the structure–soil contact element and combining it with the field monitoring data, the law of surface settlement caused by the hole pile excavation method with different thicknesses of the weak stratum has been studied. In order to improve the stability of the surrounding rock and reduce the vertical deformation of the surface, the Metro Jet System (MJS) is used to form inclined piles in the area of large surface deformation, and the effect after reinforcement was evaluated. The results show that as the weak layer thickness ratio increases, the surface settlement also increases. In the case of no reinforcement, a vertical settlement of 116 mm can be achieved when the thickness of the weak layer is 14 m. The vault of the tunnel is in the weak layer and the deformation is obvious. When the vault is not in the weak layer, the settlement is obviously reduced. After MJS pile reinforcement, under the action of soil extrusion, the self-stability of the surrounding rock is strengthened, and the oblique jet grouted pile forms a stable ‘triangle’. The vertical settlement value is basically stable at around 30 mm, which meets the requirements of the regulations. If the tunnel is not reinforced, the self-stability of the surrounding rock above the tunnel arch is poor and the maximum settlement is at the surface. After MJS reinforcement, the maximum settlement is at the vault. The vertical settlement of the ground surface can be effectively controlled by using the MJS pile forming technology in the middle of the tunnel pile driving method.

The aerodynamic performances of the wing-shaped poop sail

ABSTRACT This research proposes a wing-shaped poop which cleverly combines the poop and the wing sail. The wing-shaped poop with the length of 60 m and the height of 16.5 m is designed. The influence of the camber ratios (0.15–0.30) and the thickness ratios (0.10–0.20) on the performance of wing-shaped poop is analyzed. The lift coefficient of the poop increases first and then decreases with the increase of camber ratio and decreases with the increase of thickness ratio. The maximum lift coefficient (2.27) is obtained when the camber ratio is 0.25 and the thickness ratio is 0.1. Considering the influence of the rudder, when the apparent wind angle is 130°, the effective thrust of the poop reaches the maximum of 82 kN. Besides, when the wind comes from the bow, the shape of the poop is changed to reduce wind resistance caused by the wing-shaped poop.

Behaviour of hybrid cross laminated timber in compression perpendicular to grain in different layup structure, support conditions, and loading configurations

Cross laminated timber (CLT) is recognized as alternative to traditional construction materials. As a floor member, it causes the compressive deformation or even damage perpendicular to the grain of CLT due to vertical load imposed by the column or wall. The challenge is how to improve the compressive strength (fc,90) and elastic modulus (Ec,90) perpendicular to the grain under the high diversity of possible load configurations. Compared with normal CLT, hybrid CLT (HCLT) used structural composite materials (e.g. laminated strand lumber) instead of timber, which had more homogeneous mechanical properties. In this study, the spruce-pine-fir (SPF) and laminated strand lumber (LSL) were used to prepare HCLT. The full surface loading, point loading representing columns and line loading representing walls of HCLT in the perpendicular to grain direction were carried out. The results show that fc,90 increased with increasing thickness ratio of LSL in the total thickness of HCLT under full surface loading, the highest increase in strength of HCLT reached 35.71 %, data of Ec,90 had the opposite conclusion. In the case of point loading, the fc,90 and Ec,90 under discretely support was lower than those under successively support. Load configuration had significant influence on the fc,90 and Ec,90 including middle position (M), corner position (C), edge parallel (E) and edge vertical (V) to the grain of the outer layer. In the case of line loading, it was in good agreement with point loading results, and fc,90 and Ec,90 under line loading were lower than that under point loading. The failure modes were mainly the cracks along the wood ray direction of SPF material, while no obvious damage for LSL under full surface loading. In addition, the failure modes mainly of local loading included the shear failure for SPF material, fiber fracture failure of LSL material and the adhesive layer cracking in the non-directly compression zone.

Interfacial microstructure evolution for coordinated deformation of Mg/Al composite plates by asymmetrical rolling with differential temperature rolls

In this work, Mg/Al composite plates with different thickness ratios were prepared by the asymmetrical rolling process with differential temperature rolls and isothermal symmetrical rolling. Microstructural evolution and mechanical properties of matrix and composite materials with different thicknesses were analyzed. Influence of thickness ratios on the coordinated deformability of heterogeneous metals and interface toughness under the action of temperature gradient and shear force was investigated. Results show that the relative deformation rates of matrix and composite materials converge gradually under the influence of work hardening of Mg/Al layer. The Mg layer is mainly DRXed grains and texture intensity gradually weakens with increasing thickness ratio. The Al layer is mostly dominated by subgrains and deformed grains, which have a strong correlation with thickness ratio. Strength and plasticity of composites first increase and then decrease with increasing thickness ratio. Fracture of composite plate occurs in intermetallic compounds (IMCs). Thickness of IMCs has a strong positive correlation with thickness ratio. When the thickness ratio of AZ31B/Al6061 for 5, the relative thickness of IMCs is the largest and the relative bonding strength is the smallest. When the thickness ratio of AZ31B/Al6061 for 3, there is no element aggregation in IMCs, and the comprehensive mechanical properties of composite plate are comparatively better.

Effect of thickness ratio on interfacial structure and mechanical properties of Mg/Al composite plates in differential temperature asymmetrical rolling

Mg/Al composite plates with different thickness ratios were prepared by different temperature asymmetrical rolling + isothermal symmetrical rolling. The effects of different thickness ratios of component metals on microstructure, interface structure, and mechanical properties of composite plates were studied. It was found that the thickness of blocky intermediate compounds β(Mg2Al3) and γ(Mg17Al12) formed in the second pass rolling is inversely proportional to the component metal thickness ratio, and the maximum thickness of metallurgical bonding layer reaches 7.8 μm when the thickness ratio is 2. The main grains in matrix and clad plates are equiaxed grains and deformed grains, respectively. With the increase of thickness ratio, recrystallization of Mg layer increases first and then decreases, while Al side increases gradually because of the difference reduction of component metals. Due to the fine grain strengthening of matrix, the dislocation strengthening and low texture of clad plate, and the proper thickness of intermediate compounds, composite plate with a thickness ratio of 3 has the best mechanical properties. Its ultimate tensile strength and yield strength are 277.4 MPa and 253.9 MPa, respectively. Its elongation is the highest, up to 18.7%.

Effect of truss core on sound radiation behavior of sandwich plate structures under structure borne excitation

Compared with traditional honeycomb and stiffened sandwich structures, lattice-based structures are considered an ideal substitute for traditional core structures due to their high stiffness and other potential multifunctional application characteristics. Based on that, the sound radiation characteristics of the sandwich plate with different truss cores under structure borne excitation were investigated in the current paper, wherein three truss cores, including pyramidal, tetrahedral and 3D-kagome cores types, are considered. The governing equations for the vibration and sound radiation analysis of the sandwich plate structure are carried out using the static equilibrium method, and then solved via the Navier approach and Rayleigh integral. By comparing the experimental results, the validity of the proposed theoretical model is verified. The theoretical model is subsequently used to investigate the influences of truss core geometric parameters and types, face sheet-core face sheet thickness ratio and aspect ratio on sandwich plate sound radiation characteristics. The results indicate that, in the range [ 5 ∘ ≤ θ ≤ 52 ∘ ] and [ 52 ∘ < θ ≤ 85 ∘ ] , the tetrahedral and 3D-Kagome core types have the maximum natural frequency values, respectively, while the resonance peaks of sound pressure level curves move to lower frequency region with the increase in truss core radius and face sheet-core face sheet thickness ratio, and the sandwich plate with the 3D-kagome core shows better sound radiation characteristics in the wide frequency range.

Effect of jet plate thickness on the local heat transfer coefficient with multiple air jet impingement

For designing a multiple jet impingement cooling system, the thickness of jet plate (a passage through which jet comes out) is one of the important parameters. Considering the thermal point of view, the thickness of the plate should be chosen so that it would enhance the heat transfer rate. In this study, the effect of jet plate thickness on the local heat transfer coefficient on a flat plate with multiple impinging air jets is investigated. The thickness ratios (t/d) of 0.5, 1.0 and 2.67 are studied. Reynolds number is varied from 5000 to 20,000 and jet-to-plate distance (z/d) is varied from 1 to 5. Jet diameter (d) is chosen to be 6 mm. The jet-to-jet distance (p/d) is kept constant at 3.Steady-state thin metal foil technique, along with infrared thermography, is used to obtain the temperature distribution and thereby the heat transfer coefficient. Coefficient of discharge for each jet plate, central line velocity decay and pressure distribution on the target surface are measured. These measurements provided new insights to better understand the heat transfer results in this study. For lower jet-to-plate distances (t/d = 0.5 to 1), heat transfer decreases with the increase in the jet plate thickness ratio. However, heat transfer is not affected with the further increase in the jet plate thickness ratio i.e., t/d = 1 to 2.67. Therefore, smaller jet plate thickness ratio is suitable to obtained high heat transfer rate. This study presents a new correlation for the local Nusselt number distribution or different jet plate thickness.

Numerical Simulations of Reactive Material Double-Layered Liner Shaped Charge Penetrating Steel Target

The jet formation and penetration behaviors of shaped charge with a reactive material double-layered liner (RM-DLL) are presented in this paper based on the AUTODYN-2D code. Numerical results show that the wall thickness ratio of the RM-liner to the metal liner has a significant influence on the formation and penetration characteristics of composite jet. As the wall thickness ratio increases, the tip velocity of composite jet, the pressure on the RM-liner, and the temperature of RM-elements decrease. The effect of the wall thickness ratio on the penetration performance of RM-DLL shaped charges against steel targets significantly depends on the RM-initiation delay time (τ). The penetration depth (PD) of the composite jet with titanium liner into the steel target is limited. In the case of the RM-tungsten liner, the RM-mass following into the penetration crater is very small. In the case of the RM-copper liner, the penetration capability of composite jet is well matched with the mass of follow-thru RMs. Compared with the PD, the standoff has a more significant impact on the RM-mass entering the penetration hole.

Evaluation of the displacement discontinuity method on wave propagation through a thickly jointed rock mass

The displacement discontinuity method (DDM) has been commonly utilized to investigate the wave propagation in the jointed rock mass, in which the joint thickness is assumed to be infinitely thin. However, naturally filled joints are usually thick. To investigate the wave propagation through the thickly joint and evaluate the applicability of DDM in studying stress waves through the thickly joint, a study of stress waves across the filled joints with thickness was conducted. The wave transmissions through rock mass with different joint thicknesses and wave impedance ratios of the rock and joint were analyzed. The effects of the joint thickness and wave impedance ratio on wave transmission coefficient were discussed. Finally, the accuracy of DDM prediction was validated. The results show that the transmission coefficient decreases as joint thickness and wave impedance ratio increase. It is noted that the prediction accuracy of DDM is affected not only affected by joint thickness, but also highly affected by wave impedance ratio in front of and behind the joint. The prediction accuracy of DDM decreases as the joint thickness and wave impedance ratio increases. DDM studies the wave attenuation with high accuracy when the joint thickness and wave impedance ratio are small.