Joint Filler Research Articles

Influence of arch action on load-carrying capacity of double-sized industrial precast slabs: A combined numerical and experimental study

The precast industry offers slab panels of different geometries according to the field conditions. These slab panels are popular in temporary constructions and beneficial in sustainability but have some financial limitations and local constraints. For a long time, the construction industry has used the arch action method, which restricts the stresses to the compression zone in concrete members and develops the required load-carrying capacity. For the same motives, industrial buildings have preferred semi-circular precast roofs, but the morphology was not suitable. For the proposed slab in this research, firstly, the typical industrial precast slab panel was doubled in width to minimize the time and efforts required for its casting, curing, and placement. Secondly, that doubled-in-width slab was provided with the arch action to confine the stresses to compression and benefit from the section entirely. Lastly, the top of the slab was kept flat to take advantage of the roof space. All these changes aimed for structural stability, reduced material's weight, improved load-carrying capacity, appropriate mobilization, and financial viability. A numerical approach and practical testing were adopted using the finite element modeling software, ABAQUS, to analyze load–deflection responses of both slabs through the concrete damage plasticity model. The proposed slab exhibited better performance as its capacity enhanced by about 1.5 times that of a typical slab. Although the volume of the material in the proposed slab increased slightly from 0.040 m3 to 0.045 m3, the reductions in joint filler materials, reinforcements, and efforts required for mixing and lifting machinery compensated for this increase significantly. Hence, the slab can be recommended for the industry to save the costs while taking heavier loads efficiently.

Research on the Proportion and Strength of Joint Filler Materials for External Wall Tiles

Tile is the main exterior material of reinforced concrete building in Taiwan. However, the tiles are peeled off due to the deterioration of the building or the force of the earthquake recently. The construction sequence of exterior wall tiles includes cement mortar, waterproof layer, adhesive layer, paste tile and caulk. Most of tiles peel off from the adhesive layer so there are many studies focusing on the construction of adhesive layers. If the adhesive is not applied during construction or deteriorates over the years, it will lose its adhesion, and the caulk plays an important role in fixing the tile to the wall. Therefore, it is necessary to study the joint filling of exterior wall tiles. In this study, the exterior wall construction problems are sorted out, workers often ignore the proper water-cement ratio due to rush work in the construction site. The purpose of this study is to verify the effect of the water-cement ratio of the tile joint filler on the strength by pull-off and shear experiments. Set the water-cement ratio of joint filler to 1:4, 1:2, 1:1.3, 1:1, and quantitatively use in the same area. The results showed that the caulk with a water-cement ratio of 1:4 showed the best pull-off strength, which is 4.5 times that of 1:2. The increase in water volume at the construction site due to rush would lead to a significant decrease in strength. We look forward to providing a reference for on-site construction in this study.

Small-scale testing of air barrier systems adhered to sheathing boards under in-plane cyclic loading simulating a seismic event

Envelope air leakage is a large contributor of energy loss in modern high-performance construction. Building enclosure designers along with the building science community are emphasizing the importance of incorporating air barrier products in the envelope design. Furthermore, regulators are reassessing the allowable air leakage limits prescribed in local codes, to reduce unintentional infiltration. Although voluntary, Passive House building standards inform methods and targets for achieving minimal air leakage values to meet certification. Commercial air barrier products often satisfy the airtightness requirements during and immediately following construction. However, seismic events could potentially damage the air barrier product and compromise the envelope’s air tightness. This paper presents the findings of an experimental program conducted to test commercially available air barrier products under in plane cyclic loading. A cyclic loading profile was designed to simulate a seismic event. Selected air barrier products were adhered to small-scale sheathing panels and tested after curing. Multiple combinations of sheathing board material and air barrier tapes were tested. The tested sample groups represent the most common air barrier systems used in the industry, incorporating 3 M Construction Seaming Tape, Siga Wigluv 60, Prosoco R-Guard Joint and Seam Filler, and Zip System Tape. The failure load and failure displacement were recorded for each test, along with the corresponding failure mode. The results of the experimental program suggest that 0.5-inches [1.27 cm] of in plane vertical displacement could completely compromise the air barrier layer due to the delamination or tear of the air barrier sealant.

The effect of silica nanoparticles on the dustiness of industrial powders

Industrial powders are prompt to be airborne during processing. High dustiness levels may cause process complications like cross-contamination, product loss and filter clogging while increasing the risk of inhalation, dust explosion and fire. Thus, dustiness is often associated with occupational exposure. Despite this, powder products are usually composed of multiple ingredients with silica nanoparticles (S-NP) systematically added to ease their handling. Surprisingly, the relationship between dustiness and product formulation has not been commonly studied. This work investigates the influence of S-NP, SIPERNAT D10 (SD10), on the dustiness of four industrial powders–Avicel PH102, wheat flour, joint filler, and glass beads–using two standard methods: the rotating drum (EN 15051–2) and the vortex shaker (EN 17199–5). Our results show that the dustiness of mixtures powder + SD10 are statistically higher than those of the powder alone and can reach the levels of SD10. TEM micrographs from airborne particles collected in the vortex shaker showed that SD10 detached from the surface of the powder during aerosolisation, emitting nanometric dust; adding SD10 increases the potential for inhalation exposure during industrial processing and handling. Surface energy analysis by inverse gas chromatography (IGC) leads us to conclude that stronger powder-to-SD10 interactions result in less dust emission.

Joining of SiC ceramics using high-silicon aluminum alloy fillers assisted by laser cladding

A Si–40Al joining transition layer was prepared via laser cladding, followed by brazing of SiC ceramics using Si–60Al alloy as the joint filler. The microstructure, composition, and flexural strength of the brazed joints were investigated under different brazing temperatures and holding times. The corrosion resistance of the joints was evaluated using a hydrochloric acid immersion test. The laser cladding layer effectively reduced interfacial stress, enhanced interfacial bonding, and suppressed the formation of brittle intermetallic compounds. The main constituents of the brazed joint were Si, Al2O3, and SiC, with newly formed SiC at the interface promoting interfacial bonding. The flexural strength of the brazed joint held at 900 °C for 30 min exceeded 279 ± 13 MPa, equivalent to that of the SiC substrate. Compared to direct brazing of SiC using Si–60Al alloy filler and Si–40Al alloy filler, the strengths were increased by 49% and 94%, respectively. Furthermore, the joints exhibited excellent corrosion resistance, with a flexural strength of 177 ± 11 MPa after 10 h of hydrochloric acid immersion.

A novel phase change composite with ultrahigh through-plane thermal conductivity and adjustable flexibility

With the rapid development of micro-nano electronics, thermally conductive materials with remarkable through-plane thermal conductivity (κ⊥) and great flexibility are greatly urgent to effective thermal management. The fillers with high thermal conductivity (TC) are commonly assembled to achieve this target. However, the imperfect contact between the joint fillers will lead to high thermal resistance (R), hindering thermal transport. Herein, we fabricated thermal interface materials (TIMs) with ultra-high κ⊥ (up to 168.4 W m−1 K−1) and adjustable flexibility by the combination of highly thermally conductive carbon fiber bundles (CF) and polymer encapsulated phase change materials (PCMs). The alignment of consecutive CF guarantees the continuity of thermal paths, greatly facilitating thermal transport. While the slantly slicing technique and softening effect of PCMs beyond phase transition temperature lead to an attenuated compression stress (1.6 MPa@10% strain with a CF loading of 50 wt%). What’s more, the latent heat absorbed by PCMs is also conducive to thermal management. Thus, during a CPU temperature-control experiment, the application of as-prepared TIMs manifests a temperature decline of 33.9 °C of CPU. This work opens a new perspective to fabricating TIMs with ultrahigh κ⊥ and low compression stress (σ) by the combination of thermally induced flexible matrix and the slantly slicing technique of aligned CFs.

Evaluation of Physical Properties and Material Characterization for Structural Frame at the Stained Glass Windows to Gongju Jeil Church of the Registered Cultural Heritage in Korea

AbstractThe Christian Museum of Gongju Jeil Church was first built in 1931 and was largely damaged during the Korean War, but the walls and chimneys have been preserved. This building has a high architectural values in that the chapel was reconstructed in 1956, and maintains its original form through repair of damaged parts rather than new construction. The stained glass windows were as installed in 1979 and has a great significance in the Dalle de Verre method using lump glass. However, some of the stained glass damaged partially, such as various cracks and splits, and vertical and horizontal cracks in the joint fillers of supporting the colored glass. As the structural materials of the stained glass window, an iron frame and cement mortar filled with it were used, and corrosion of iron, cracking of mortar and granular decomposition appear partially due to weathering. In the joint fillers, the content of Ca and S is very high, indicating that gypsum were used as admixtures, and the gypsums grow in a rhombohedral and forms a bundle, which is investigated to have undergone recrystallization. As a result of modeling the ultrasonic velocity at the joint fillers, the left and right windows at the entrance show relatively weak in the range of 800 to 1,600m/s, and the lower right corner of the altar window and the upper left corner of the center window were also 1,000 to 1,800m/s, showing relatively low physical properties. And gypsums produced during the neutralization of lime mortar were detected in the joint fillers and contaminants on the surface. Such salts may cause damage to the joint material due to freezing and thawing, so appropriate preventive conservation is required. Also, since various damage types are complexly appearing in stained glass window and joint filler, customized conservation treatment should be reviewed through clinical tests.공주제일교회 기독교박물관은 1931년에 초축되었으며 한국전쟁으로 상당 부분 파손되었으나 벽체와 굴뚝 등이 보존되었다. 이 건물은 1956년 예배당을 재건하며 신축이 아닌 파손된 부분의 보수를 통해 원형을 유지하고 있다는 점에서 건축학적으로 높은 가치가 있다. 스테인드글라스는 1979년에 설치하였으며, 덩어리유리를 사용하는 달드베르(Dalle de Verre) 방식으로 큰 의미가 있다. 그러나 일부 스테인드글라스에서는 다양한 균열과 쪼개짐이 나타나고 색유리를 지지하는 줄눈에는 수직 및 수평균열이 확인되는 등 부분적인 손상을 입었다. 스테인드글라스의 구조재로는 철제 틀과 이를 충전한 시멘트 모르타르가 사용되었으며, 부분적으로 풍화작용에 따라 철제의 부식과 모르타르의 균열 및 입상분해가 나타난다. 줄눈재에서는 Ca과 S의 함량이 높아 석고를 혼화재로 사용하였음을 지시하며, 석고는 능형으로 성장하며 다발모양을 이루고 있는 것으로 보아 재결정작용을 거친 것으로 판단된다. 줄눈재의 초음파속도 모델링 결과, 입구 좌우창의 속도는 800~1,600㎧ 범위로 상대적으로 취약하며, 제단의 좌창 우측 하단과 중앙창 좌측 상단도 1,000~1,800㎧로 나타나 상대적으로 낮은 물성을 보였다. 또한 줄눈재와 표면오염물에서는 석회 모르타르의 중성화에서 생성되는 석고화합물이 검출되었다. 이와 같은 염류는 동결 및 융해작용에 따라 줄눈재의 손상을 일으킬 수 있어 적절한 예방보존이 필요하다. 스테인드글라스와 줄눈재에는 다양한 손상유형이 복합적으로 나타나고 있어 임상실험을 통해 맞춤형 보존처리를 검토해야 할 것이다.Keywords : stained glass window, joint filler, cement mortar, ultrasonic velocity, preventive conservation

Research on the creation of a joint filler on the basis of a trailed tractor

This article is dedicated to the development of a joint filler for cracks in asphalt concrete pavement, as well as for expansion joints in cement concrete pavement. The article presents the choice of unified units and units of the joint filler unit being developed for cracks in asphalt concrete pavement and for expansion joints in cement concrete pavement. Some methods for calculating the main parameters of the created joint filler are presented. In addition, a suitable prototype of a joint filler, cracks in the asphalt concrete pavement and expansion joints in the cement concrete pavement were selected from several types.

EFFECTS OF BAMBOO CELLULOSE MICRO-FIBERS ON MECHANICAL CHARACTERISTICS AND POROSITY OF CEMENT MORTAR

This study presents the effect of utilizing cellulose microfibers obtained through extraction from bamboo as reinforcement on mortar mixtures. The mixture proportions used in this experiment are 0.5%, 1%, 1.5%, and 2% of bamboo cellulose fiber by weight of cement as additional material in mortar mixture. It was found that the optimum compressive strength of 36.4 MPa was achieved by the sample with 1.5% of bamboo cellulose fiber as additional material with water to binder ratio of 0.5. A similar trend was also found in the result of flexural strength of mortar due to bamboo cellulose fiber addition, reaching the value of 6.31 MPa on the 28th day, which is 52% higher than the flexural strength of control mortar. From the porosity results, the percentage of mortar porosity containing micro-fibers ranged from 4.6-9.1%, lower than the porosity of control mortar, indicating that the addition of fibers led to fill in the pores, resulting in a denser cement matrix. The performances of the cellulose fiber contributed to the strength development and porosity resistance of mortar even with low volume fraction, making it a potential to be used as material building construction, for instance, masonry mortar, repair mortar, rendering mortar, joint filler, waterproof mortar, decorative mortar and for precast elements in construction. The research findings also provide new perspective on the utilization of natural cellulose fibers as a sustainable construction material.

Effect of fluxes on weld penetration during TIG welding – A review

Tungsten Inert Gas (TIG) welding, also known as Gas Tungsten Arc Welding (GTAW), is a common welding procedure which produce high quality weld with composition as close to that of parent metal. Wide range of materials like, ferrous alloys, magnesium alloys, Aluminum alloys and Titanium alloys can be welded using TIG welding process. Conventional TIG welding can only produce a maximum penetration of 3 mm in a single pass. Alloys with higher thickness require multi-pass TIG welding which involves preparation of joint and additional filler. This leads to the increase in production cost and higher heat input which leads to increased thermal stress and distortion of weld. This paper reviews recent novel developments to improve the penetration depth in TIG welding of various materials. The application of Activated Flux induced TIG welding (A-TIG), Flux Bounded TIG welding (FBTIG) and Flux cored wire TIG of A-TIG on Ferrous alloys, Titanium alloys, Magnesium alloys and Aluminum alloys are discussed. The paper also discusses about the mechanism involved in improving the penetration of weld in these three processes. It also discusses the future scope of application of these processes.

Investigating the Influence of Joint Reinforcements of Portland Cement Concrete Slabs Under Asphalt Concrete Overlays on Vertical Deflections Using Accelerated Pavement Testing

Joint gaps between slabs in underlying Portland cement concrete (PCC) pavements are critical factors in the life span of asphalt concrete (AC) overlays. Therefore, being informed about the vertical deflections that may occur around the joints is important. In this study the joints were reinforced with three different materials: ethylene propylene diene monomer (i.e., rubber joint filler [RJF] reinforcement), bitumen-based sealant (i.e., rubber plate [RP] reinforcement), and steel plate (SP) (i.e., SP reinforcement), to limit the vertical movement of the underlying PCC. Tests were conducted at the accelerated pavement testing facility for two different AC overlay thicknesses, 50 mm and 100 mm, during 100,000 passages to investigate the influence of AC overlay thickness variations on slab vertical deflections and to also evaluate types of joint reinforcement on slab vertical deflections. For 50-mm thick AC overlay, the most effective joint reinforcements to prevent deformations caused by loading were RP, RJF, and SP; for a 100-mm thickness, this was determined to be RJF, SP, and RP, respectively.

Effects of healing agent on shape memory, mechanical and self- healing properties of joint filler on cement concrete pavement

To improve the self-healing performance of joint filler on cement pavement and determine the healing agent content for preparing titanium dioxide/ shape memory polyurethane (TiO2/SMPU) composite as joint filler, the influences of PCL content on different properties of TiO2/SMPU joint filler were investigated before and after the two-stage uniaxial training, as well as after free recovery. Results indicate that the shape memory transition temperature of TiO2/SMPU joint filler and melting temperature of healing agent of thermoplasticpolycaprolactone (PCL) meet the requirements of two-stage uniaxial training and two-step self-healing of TiO2/ SMPU joint filler. Also, SMPU matrix has a good compatibility with PCL particles, and there are no chemical reactions between PCL and TiO2/SMPU. The physical cross -linking reactions between PCL and SMPU matrix occur during the self-healing at high temperature, providing a basis for PCL to repeat the self-healing. After the two -stage uniaxial training, TiO2/SMPU joint filler shows satisfactory shape memory performance, but when PCL content is more than 10%, TiO2/SMPU joint filler shows lower shape memory effects. Additionally, the two-stage uniaxial training method improves the mechanical properties and repeated self-healing ability of TiO2/SMPU joint filler after the two-step self-healing method. Finally, the PCL content of 10% is suggested to prepare TiO2/SMPU joint filler of expansion joint after the two-stage training to reduce the damages of cement concrete pavement.

Effect of Emulsion Powder Content in VAE Emulsion on Tensile Properties of Joint Filler

The traditional joint filler used in our country is easy to be damaged by the environment. At present, polymer composite is used to form a new type of polymer joint filler (NPJF) to improve the properties of joint filler. In this paper, by comparing and testing the various indexes of the joint filler under tensile load under the condition of 5 kinds of latex powder content, the performance of the joint filler after molding was studied. The results show that the tensile strength and tensile modulus of the joint filler increase with the increase of latex powder content, the elongation at break and peak strain decrease first and then increase. The influence of the amount of latex powder on the tensile properties of the joint filler mainly lies in the improvement of the aggregate ash ratio, the formation of the film structure and the change of the overall microstructure.

Effects of welding technique, filler metal and post-weld heat treatment on stainless steel and mild steel dissimilar welding joint

Joining of two materials having different physical, chemical, and thermal properties and to make the joint tough and stiff, special attention and investigation are required. In this research, the welding joint between stainless steel (SS) of grade AISI 304 and mild steel (MS) of grade AISI 1020, was accomplished by using shielded metal arc welding (SMAW) and tungsten inert gas (TIG) welding process. To investigate the effect of filler material in the dissimilar welding joint, both MS and SS filler material was exercised. For post-weld heat treatment (PWHT), three distinct temperatures of 600 °C, 630 °C, and 650 °C were investigated over the welded specimens. To explore the optimum welding process and PWHT process for this dissimilar joint, both tensile and bending tests were carried out. Destructive tests have suggested that PWHT at 630 °C is better for the SMAW process with both MS and SS electrodes and PWHT at 600 °C is more suitable for TIG welding process with both MS and SS filler rod. Both optical and SEM micrographs showed that the amount of δ ferrite and martensite is higher in the as-welded situation. The coarser grain structure was observed in the heat-affected zone (HAZ) which makes the sample susceptible to failure. This is the region where the hardness values were the smallest. The hardness values have decreased after PWHT which justified the achievement of higher ductility after heat treatment. After conducting fracture analysis by SEM, it has been noticed the specimen becomes more ductile after PWHT. The best solution based on the mechanical, microstructural, and fracture analysis concluded that TIG welding with MS filler rod and PWHT at 600 °C is the optimum condition for joining SS AISI 304 with MS AISI 1020.

Experimental Study on Mix Ratio Design and Road Performance of Medium and Small Deformation Seamless Expansion Joints of Bridges

Expansion joints are a weak and fragile part of bridge superstructure. The damage or failure of the expansion joint will lead to the decline of bridge durability and endanger the bridge structure and traffic safety. To improve the service life and performance of bridge expansion joints, the ideal method is to use seamless expansion joints. In this study, starting from the commonly used asphalt mixture gradation of seamless expansion joint, and taking into account the actual situation of bridge expansion joint structure and environment in China, the gradation and asphalt-aggregate ratio are preliminarily designed. Through a Marshall test, the corresponding asphalt mixture is evaluated and analyzed according to the stability, flow value, and void ratio, and the optimal gradation and asphalt-aggregate ratio are determined. Finally, the asphalt mixture is prepared with the mixture ratio design, and the test results of an immersion Marshall test, fatigue performance test, and full-scale test verify that the asphalt mixture meets the road performance requirements of seamless expansion joints. On the basis of the experimental data, the performance of large sample asphalt mixture is continuously tested, compared, and optimized. The results show that the asphalt mixture ratio designed is true and reliable, which can provide reference for the optimal design of seamless expansion joint filler.

ВИКОРИСТАННЯ ГОТОВИХ УЩІЛЬНЮВАЧІВ ШВІВ В ЦЕМЕНТОБЕТОННИХ ПОКРИТТЯХ АВТОМОБІЛЬНИХ ДОРІГ І АЕРОДРОМІВ

Increased requirements for reliability, performance and durability of pavement caused by the increase in vehicle carrying capacity and traffic on the roads. As the domestic and world experience shows, the increasing requirements of the movement are best matched by cement concrete pavements. Stable transport transport performance, high durability give them advantages over pavements built using organic binders. During construction and reconstruction, longitudinal and transverse joints for various purposes are arranged in cement concrete pavements of roads and airfields to prevent deformation and destruction of coating pavements (cracking, chipping of corners and edges of slabs, peeling of the concrete surface layer, the appearance of potholes and sinks, vertical displacement of slabs and their warpage destruction of butt joints and joint fillers). The destruction of pavements, as a rule, takes place in cases where the stresses and deformations arising in the plates exceed the permissible values, as well as in case of failure of the sealing of joints and cracks. Restoring the sealing of expansion joints and cracks are important stages of work to extend the operational life of pavements. A large role on the efficiency of the sealant in the joints and its service life is provided by the deformability of the sealing materials. When choosing a type of sealant, the possible maximum negative and positive air temperatures of the region where the pavements are used are taken into account. Currently, unique sealing materials using polymer compositions have been created. These materials have high technical and operational characteristics and a guaranteed service life of at least 5 years. The sealing or filling of transverse and longitudinal joints in cement concrete pavements is an important factor in ensuring long-term performance of the coating. The experience of using different types of joint sealing materials shows that their proper installation can provide important protective equipment that improves the performance of joints and pavements. In recent years, in foreign practice, the technology of pressing elastic whole or porous rubber profiles into the seam is very often used for sealing joints. In this case, it is possible to carry out work even in wet weather and at low temperatures. Special machines have been developed for the installation of profiles. The article discusses the sealing of transverse and longitudinal seams of cement concrete pavements of roads and airfields with sealing materials, including ready-made seals, the need to use them and study the effect of sealing materials on the design of joints and operational performance of cement concrete coatings in general.

Assessment of the Mechanical Properties of ESD Pseudoplastic Resins for Joints in Working Elements of Concrete Structures.

Concrete structure joints are filled in mainly in the course of sealing works ensuring protection against the influence of water. This paper presents the methodology of testing the mechanical properties of ESD pseudoplastic resins (E-elastic deformation, S-strengthening control, D-deflection control) recommended for concrete structure joint fillers. The existing standards and papers concerning quasi-brittle cement composites do not provide an adequate point of reference for the tested resins. The lack of a standardised testing method hampers the development of materials universally used in expansion joint fillers in reinforced concrete structures as well as the assessment of their properties and durability. An assessment of the obtained results by reference to the reference sample has been suggested in the article. A test stand and a method of assessing the mechanical properties results (including adhesion to concrete surface) of pseudoplastic resins in the axial tensile test have been presented.

ЗАПОВНЕННЯ ДЕФОРМАЦІЙНИХ ШВІВ МІЖ КАРКАСОМ ТА НЕНЕСУЧИМИ СТІНАМИ ПРИ СТИСКУЮЧОМУ НАВАНТАЖЕННІ

Метою даної статті є вивчення поведінки різних видів заповненняантисейсмічних швів між елементами каркаса і ненесучих стін нароботу багатоповерхових будівель з залізобетонним безрігельнимкаркасом при сейсмічних впливах. Вплив заповнення було проаналізовано на найбільш широко застосовуваних в Україні трьох видах заповнення: мінеральної вати, пінополістирола і вілатерм. Об'єктами дослідження є три газобетонні призми і одна призма з важкого бетону з матеріалом заповнення швів при стискаючих навантаженнях. Переміщення від вертикальних навантажень на випробуваних зразках – ключові параметри для визначення впливу утеплювача на поведінку будівель зі стіновим заповненням під час землетрусів.Другим параметром, який також був проаналізований, є зміна геометричної форми і повного руйнування заповнювача шва (утеплювача).

Energy flow transmission analysis on the powerhouse vibration under turbine hydraulic loads

The vibration of the powerhouse in hydropower station mainly originated from the dynamic loads of turbine and generator set. In the vibration conductivity path there have gain amplification or reduction, so the transmissibility analysis and the transfer path recognition are very important to the vibration analysis and its treatment. Based on energy flow finite element methods, the vibration transmissibility of the powerhouse under turbine dynamic loads was analyzed in this paper. Firstly, the energy transfer characteristics of the different slab structures were analyzed and the results could provide some valuable helps for the vibration control. Secondly, vibrational power flow from spiral case into the upper structures such as pier, wind cover, slab and wall were studied. It is concluded that the supporting structure are the main path for the energy flow, and the reduction effects of the thick slab and wall are much more remarkable. Finally, the law of dominant path recognition was first proposed with a numerical solution. The vibration transmission from the main hall to the auxiliary power house was calculated for the different paths such as joint, foundation and rock around. The results indicated that as a kind of structural joint filler, the closed-cell foam could actively restrict the vibration transmission.

Assessment of failure and cohesive zone length in co-consolidated hybrid C/PEKK butt joint

The failure mechanisms and the cohesive zone length (CZL) during fracture of a recently developed butt jointed thermoplastic composite are evaluated in this paper. The laminated skin and the web were made of AS4/PEKK. The butt joint (filler) was injection molded from 20% short AS4 filled PEKK. The skin and web were co-consolidated together with the filler to form a hybrid butt joint structure. The crack initiation and propagation in the filler and the delamination at the skin-filler interface were captured using a high-speed camera. It was found from the experimental observations that the crack initiated in the filler and then propagated towards the skin-filler interface in less than 33 μs under three-point bending. A numerical model was developed using the finite element method in ABAQUS to predict the failure and CZL. The crack initiation and progression in the filler was predicted using the Virtual Crack Closure Techniques (VCCT) and the delamination at the skin-filler interface was modelled using the cohesive surfaces. The predicted stiffness of the specimen, the location of crack initiation and propagation as well as the force drop during delamination were in good agreement with experiments. The development of CZL was critically assessed and it was found that the CZL increases during mix mode delamination. The effect of interface strength and critical energy release rate on the CZL was investigated in the parameter analysis.