Maximum Compressive Load Research Articles

Strength and Axial Behavior of Cellular Lightweight Concrete-Filled Steel Rectangular Tube Columns under Axial Compression

This paper presents the experimental results on the strength and axial behavior of rectangular steel tube columns filled with cellular lightweight concrete (CLC) under axial compression. A total of 24 specimens, including 6 reinforced cellular lightweight concrete (RCLC) columns and 18 cellular lightweight concrete-filled steel tube (CLCFT) columns are investigated. The nominal dimension of the rectangular columns are 150×75 mm in cross-section and 750 mm in height. The parameter used in all tests are the ultimate compressive strengths of the CLC, which are 15 MPa, 20 MPa and 25 MPa, and the wall thicknesses of steel tubes, which are 3.0 mm, 4.5 mm and 6.0 mm. All specimens are prepared and loaded concentrically in axial compression to failure. The results of these tests demonstrated that the CLCFT columns have a linear behavior up to the approximately 80-90% of their maximum compressive load. Then, the behavior of the columns is nonlinear. The nonlinear behaviors are due to the crushing of the concrete core and local wall buckling of the steel hollow tube. In addition, it is found that the CLCFT columns have high axial deformability at the failure when compared to the reference RCLC columns. Finally, by comparing the maximum compressive load of the test results with those obtained from the ACI composite design equation, the comparison results show that calculation formula in ACI code can be applied to compute the axial capacity of CLCFT columns under axial compression.

Structural grading of three sympodial bamboo culms (Hitam, Andong, and Tali) subjected to axial compressive load

Bamboo culm is commonly utilized in columns that are subjected to axial compressive load, thus it is necessary to measure its compressive strength and load-carrying capacity. The variability of culm dimension, geometry, moisture content, density, and linear mass of three sympodial bamboo species belonging to the Gigantochloa genus [Hitam (Gigantochloa atroviolacea), Tali (G. apus), and Andong (G. pseudoarundinacea)] were studied to determine the best predictor for structural grading of these culms based on their compression properties. Two types of structural gradings, strength and capacity gradings, were examined. Strength grading was developed assuming a hollow or solid circular section of the bamboo culm. Both strength and capacity gradings sufficiently classified culms of all three species into several structural quality classes based on a strong correlation (r) between the predictor and dependent variable (r = 0.83–0.97); however, capacity grading proved to be the best type of structural grading because the maximum compressive load carrying capacity (Fc) of bamboo culm could be predicted more precisely and accurately compared with the compressive strength (σc). Additionally, it was found that linear mass was the best predictor for estimating the compressive capacity (Fc) (r = 0.89–0.98), culm density for estimating compressive strength assuming a solid circular section (σcc) (r = 0.84–0.92), and wall density for estimating compressive strength assuming a hollow circular section (σcw) (r = 0.73–0.89). Based on these predictors, capacity and strength gradings for bamboo culms subjected to compressive load were developed, permitting categorization of bamboo culms into structural quality classes. Each structural quality class had a 5% lower value and characteristic value for σc and the maximum compressive load, which became design values for bamboo structural design.

Numerical Study of Experiment Setup for Aluminum Foam Sandwich Construction Subjected to Blast Load

Numerical study of experimental setup to evaluate aluminum foam sandwich construction undergoing blast loading is introduced. Aluminum foam sandwich has excellent compression characteristic on absorbing blast impact energy through massive cellular deformation. A case study on an add-on structure of armored vehicle floor is discussed. A finite element prediction using LS-DYNA on the proposed blast experimental setup was constructed to calculate peak force and acceleration. The aims of this preliminary study are to obtain load cell and accelerometer sensors capacity that installed on the setup when subjected to 8 kg TNT blast loading. The load cell is placed on the leg support and the accelerometer is placed on the central point of the occupant side steel. The prediction results give maximum compression load up to 631 kN so that the available load cell for this capacity is 9107A (Kistler) that has maximum compression load 700 kN. For accelerometer, the maximum acceleration is 16114 G. The available accelerometer for this capacity is 350D02 (PCB) that has maximum and minimum acceleration up to ±50.000 G.

Load-Bearing Capacity and Retention of Newly Developed Micro-Locking Implant Prosthetic System: An In Vitro Pilot Study.

The aim of this study was to introduce the newly developed micro-locking implant prosthetic system and to evaluate the resulting its characteristics. To evaluate load-bearing capacity, 25 implants were divided into five groups: external-hexagon connection (EH), internal-octagon connection (IO), internal-hexagon connection (IH), one-body implant (OB), micro-locking implant system (ML). The maximum compressive load was measured using a universal testing machine (UTM) according to the ISO 14801. Retention was evaluated in two experiments: (1) a tensile test of the structure modifications of the components (attachment and implant) and (2) a tensile test after cyclic loading (total 5,000,000 cycles, 100 N, 2 Hz). The load-bearing capacity of the ML group was not significantly different from the other groups (p > 0.05). The number of balls in the attachment and the presence of a hexagonal receptacle did not show a significant correlation with retention (p > 0.05), but the shape of the retentive groove in the implant post had a statistically significant effect on retention (p < 0.05). On the other hand, the retention loss was observed during the initial 1,000,000 cycles, but an overall constant retention was maintained afterward. Various preclinical studies on this novel micro-locking implant prosthetic system should continue so that it can be applied in clinical practice.

Non-invasive anterior cruiciate rupture device for clinincally relevant in vivo rat models

Purpose: There exist promising opportunities to improve pharmaceutical efficiency of osteoarthritic (OA) drugs by advancing intra-articular drug delivery systems. However, the study of intra-articular fate of therapeutics in OA joints is limited by readily available in vivo models. Common models include chemical ablation of cellular activity in the joint, which poorly resembles the human condition, and surgical destabilization, which disrupts the integrity of the joint capsule, thereby impacting joint clearance and biodistribution of therapeutics. Here we present the development of a Non-Invasive Knee Injury (NIKI) device that delivers an external force in skeletally mature rats to rupture the anterior cruciate ligament (ACL), an injury that commonly leads to OA in humans. Non-invasive ACL ruptures have been successful in mice, but few studies have involved rats. In this study, device parameters needed for successful ACL rupture were assessed in rat cadavers, immediately post mortem. Future work will evaluate the biological, behavioral, and structural consequences of the injury. Ultimately, we aim to develop a biologically and clinically relevant model of PTOA with an undisrupted synovial capsule. Methods: A linear pneumatic thruster was mounted to a t-beam and the system was controlled by manually varying the pressure regulator voltage. Euthanized Lewis rats (322.9 g ± 22.3 g) were placed supine with the knee and foot secured in 3D-printed mounts such that a compressive vertical load translated the femur relative to the tibia. To evaluate if leg orientation affected ACL rupture rate, mount angle was laterally rotated such that the feet were 36°, 46°, 56°, or 66° relative to the body midline, and a compressive force of 70.8 N was delivered to the knee at 2.24 N/s. To evaluate the effect of loading rate, knees were subjected to 77.9 N at 1.93 N/s or 2.77 N/s. For all studies, ACL condition was evaluated by gross dissection and rated based on visual assessment of tear severity. The presence of tibial draw was also manually evaluated relative to uninjured knees. Results: Calibration by springs indicated that the NIKI could deliver a maximum compressive load of 120N, which exceeds forces needed to rupture the ACL in Sprague Dawley rats. Fig. 1 shows the NIKI device and representative images of ACL tear severity. While higher angles had a numerically greater mean tear severity, no significant difference in tear severity was observed between foot angles. At 66°, one unintended bone injury was observed. Loading rate analysis, which was conducted at a higher maximum force than foot angle studies, had 100% of animals with at least a medium-grade tear. There was no significant difference between the two loading rates studied, and two bone injuries were observed in both loading conditions. In knees exhibiting tibial draw, 97.2% of the cases had at least a medium-grade tear, while 88.9% of the cases with no observed draw did not have a tear. Conclusions: To obtain the greatest incidence of ACL tear without bone injury, there appears to be a critical balance between anatomical orientation and maximum force applied – higher forces yielded greater rate of ACL rupture, but also were associated with increased bone fracture. Future studies will assess more anatomical positions in combination with forces between 70N and 78N to determine the conditions that yield consistent tears without bone injuries. While tibial draw is a subjective assessment, the presence of tibial draw may be a strong indicator of ACL rupture. While the NIKI device is in early stages of development, the clinically relevant joint conditions could allow this model to be used for numerous investigations including studying intra-articular fate.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Comparison of buckling strength between metallic and composite panel

In the current investigation, a comparison will be made between the Aluminium and Aluminium-Carbon Fiber Reinforced Polymer (CFRP) sandwiched composite panels for buckling load carrying capability. The panels with maximum compression load will be identified as critical panels for buckling analysis. Classical approach will be followed to calculate the critical buckling load on each panel. Testing of both panel will be carried out using Universal Testing Machine (UTM). Axial compression load will be applied on the panel. Dial gauges will be placed either side of the panel to capture the displacement about the center of the panel for response of the structure under uni-axial compression loading. Interpolation of the test results will be carried out for comparison of the buckling strength between two panels.

Thoracolumbar spine loading associated with kinematics of the young and the elderly during activities of daily living

Excessive mechanical loading of the spine is a critical factor in vertebral fracture initiation. Most vertebral fractures develop spontaneously or due to mild trauma, as physiological loads during activities of daily living might exceed the failure load of osteoporotic vertebra. Spinal loading patterns are affected by vertebral kinematics, which differ between elderly and young individuals. In this study, the effects of age-related changes in spine kinematics on thoracolumbar spinal segmental loading during dynamic activities of daily living were investigated using combined experimental and modeling approach.Forty-four healthy volunteers were recruited into two age groups: young (N = 23, age = 27.1 ± 3.8) and elderly (N = 21, age = 70.1 ± 3.9). The spinal curvature was assessed with a skin-surface device and the kinematics of the spine and lower extremities were recorded during daily living tasks (flexion–extension and stand-sit-stand) with a motion capture system. The obtained data were used as input for a musculoskeletal model with a detailed thoracolumbar spine representation. To isolate the effect of kinematics on predicted loads, other model properties were kept constant. Inverse dynamics simulations were performed in the AnyBody Modeling System to estimate corresponding spinal loads.The maximum compressive loads predicted for the elderly motion patterns were lower than those of the young for L2/L3 and L3/L4 lumbar levels during flexion and for upper thoracic levels during stand-to-sit (T1/T2–T8/T9) and sit-to-stand (T3/T4–T6/T7). However, the maximum loads predicted for the lower thoracic levels (T9/T10–L1/L2), a common site of vertebral fractures, were similar compared to the young. Nevertheless, these loads acting on the vertebrae of reduced bone quality might contribute to a higher fracture risk for the elderly.

The Effect of Anthropomorphic Test Device Lower Leg Surrogate Selection on Impact Mitigating System Evaluation in Low- and High-Rate Loading Conditions.

The lower legs are at risk of substantial injury during events such as frontal automotive crashes and antivehicular mine blasts. Loading to occupants can be assessed using an instrumented anthropomorphic test device (ATD), whose measurements can be compared to established injury criteria. NATO's AEP-55 STANAG 4569 recognizes two surrogates for lower leg injury assessments from impacts with intruding floor pans resulting from underbelly blast loads; (1) the rigid Hybrid III instrumented lower leg, and; (2) the compliant MILitary Lower eXtremity (MIL-LX). The established injury criterion for the Hybrid III leg specifies a maximum lower tibia compressive load of 5.4 kN, whereas the MIL-LX limit is 2.6 kN measured at the upper tibia for similar injury severity levels. The difference in compliance between the two legs could affect the evaluation of protection levels, resulting in an over- or under-estimation of the force attenuation of energy attenuating (EA) floor mats. The responses of the two lower leg surrogates were evaluated at impact velocities up to 12 m/s, representing floor intrusions during antivehicle mine blasts. An air cannon was used to accelerate a rigid or padded floor plate into the sole of the surrogate lower legs, loading them axially, in order to assess the protective capability of commercial EA floor mats. The peak load from the lower and upper load cells in the Hybrid III and MIL-LX legs were compared to identify at what point their respective injury criteria would be exceeded in both the padded and unpadded conditions. Comparisons of the surrogate legs' responses resulted in different evaluations of risk, with the Hybrid III leg exceeding its limit at an impact speed of 6.0 m/s, and the MIL-LX exceeding its limit at 5.5 m/s (for tests including an EA product). Furthermore, the inclusion of an EA mat had a greater relative protective effect on the Hybrid III than the MIL-LX leg, with padding reducing the force to 17 to 34% of the unpadded condition for the Hybrid III, versus 67 to 89% of the unpadded condition for the MIL-LX. The load reduction was found to be velocity dependent for both surrogates. These results indicate that the two surrogates are not equivalent in their assessment of protective capability. Therefore, the selection of ATD leg for testing of EA mats (and other protective devices) will influence the evaluation of these systems, and more robust metrics are required to identify which is the most appropriate surrogate for evaluating injury to the lower limb.

An analytical model for estimating restrainer design forces in bolted buckling-restrained braces

This article presents an analytical model to predict the normal thrust force for the design of the restraining system of all-steel buckling-restrained brace (BRB) members. The proper design of the restraining mechanism is key to obtaining a stable inelastic response from BRBs. Compared with existing models, the presented model accounts for the cyclic strain hardening behaviour of the BRB's steel core, the flexibility of the restraining system, the flow of frictional forces, the longitudinal variation of the core axial load and strain, and Poisson's effects on the core cross-section properties. The buckled shape of the core and the resulting normal thrust and frictional forces are evaluated along the core length using an iterative approach to satisfy the force equilibrium and geometric compatibility. The model predicts the maximum compressive and tensile loads resisted by the brace, buckling wavelengths, and the magnitude and distribution of the normal thrust and the frictional force along the core. Using a simplified stability analysis, the required restraining stiffness to achieve a stable inelastic response and avoid excessive gap opening is provided. A method to estimate the available restraining stiffness of a typical bolted all-steel BRB is presented and the internal actions in the restraining system resulting from the local buckling of the core are obtained through a simple and practical analysis. The analytical model is validated against the results of physical tests and finite element analyses for two different BRB members. The model was found to provide sufficiently accurate results for typical earthquake engineering applications.

A Sustainable Graphene Based Cement Composite

The rheological properties of fresh cement paste with different content of graphene nanoplatelets (GNPs), different shear rate cycles and resting time was investigated. The rheological data were fitted by the Bingham model, Modified Bingham model, Herschel–Bulkley model and Casson model to estimate the yield stress and plastic viscosity, and to see trend of the flow curves. The effectiveness of these rheological models was expressed by the standard error. Test results showed that yield stress and plastic viscosity increased with the increase in the content of graphene in the cement based composite and resting time while the values of these parameters decreased for higher shear rate cycle. In comparison to control sample, the GNP cement based composite showed 30% increase in load carrying capacity and 73% increase in overall failure strain. Piezo-resistive characteristics of GNP were employed to evaluate the self-sensing composite material. It was found that, at maximum compressive load, the electrical resistivity value reduced by 42% and hence GNP cement based composite can be used to detect the damages in concrete. Finally, the practical application of this composite material was evaluated by testing full length reinforced concrete beam. It was found that graphene–cement composite specimen successfully predicted the response against cracks propagation and hence can be used as self-sensing composite material.

Fatigue strength of bovine articular cartilage-on-bone under three-point bending: the effect of loading frequency

BackgroundThe objective of this study was to determine the influence of loading frequency on the failure of articular cartilage-on-bone specimens under three-point bending.MethodsIn this study, cyclic three-point bending was used to introduce failure into cartilage-on-bone specimens at varying loading frequencies. Sinusiodally varying maximum compressive loads in the range 40–130 N were applied to beam-shaped cartilage-on-bone specimens at frequencies of 1, 10, 50 and 100 Hz.ResultsThe number of cycles to failure decreased when loading frequency increased from normal and above gait (1 and 10 Hz) to impulsive loading frequencies (50 and 100 Hz). It was found that 67 and 27% of the specimens reached run-out at loading of 10,000 cycles at frequencies of 1 and 10 Hz, respectively. However, 0% of the specimens reached run-out at loading frequencies of 50 and 100 Hz.ConclusionThe results indicate that increasing the loading frequency reduces the ability of specimens to resist fracture during bending. The findings underline the importance of the loading frequency concerning the failure of articular cartilage-on-bone and it may have implications in the early onset of osteoarthritis.

Modeling and Control of the CSCEC Multi-Function Testing System

In order to promote the research and development on evaluating the seismic performance of structures, China State Construction Engineering Corporation (CSCEC) planned to construct a large-scale loading testing facility, the Multi-Function Testing System (MFTS). This facility can perform full-scale, real-time, 6-degree-of-freedom static and dynamic testing of rubber bearings and many types of structural components including long columns, shear walls and cross shape joints. The basic performances of the MFTS are a clearance of 9.1 m × 6.6 m × 10 m for specimen installation, maximum x-directional displacement 1500 mm, maximum y-directional velocity 1570 mm/s and maximum z-directional compressive load 108 MN. The system configuration and performance specifications of the MFTS are presented in this paper. The inverse kinematics model and the nonlinear model of the hydraulic servosystem of the MFTS are built. A modified feedback forward kinematics algorithm is developed for real-time control of the MFTS. Internal force characteristics of the loading system are analyzed. The internal force control method based on real-time solution of basis of internal force space is proposed for the system with large motion ranges. The motion controller combining position control loop and internal force control loop is developed. To meet the requirement of simultaneously imposing vertical compressive load and horizontal displacement, a mixed load and displacement controller is designed, where a direct force control loop is used to improve the response speed of the force control and reduce spatial dynamic coupling effects. Finally, a dynamic bearing testing is performed. The test results demonstrate that the system using the proposed controller has good abilities on position tracking, force balance, and load following.

Damage modeling for carbon fiber/epoxy filament wound composite tubes under radial compression

The focus of this study is the development of a computational model with damage to predict failure of carbon fiber/epoxy filament wound composite tubes under radial compressive loading. Numerical analysis is performed via Finite Element Method (FEM) with a damage model written as a UMAT (User Material Subroutine) and linked to commercial software. The experimental analysis carried out followed ASTM D2412-11, where the specimen is parallel-loaded by two steel-based plates. Three stacking sequences have been evaluated. Both numerical and experimental results show that the presence of hoop layers at inner and outer layers plus ±75° non-geodesic layers gives maximum compressive load to the composite tube, since the reinforcement is wound closer to the loading direction. Moreover, failure modes are predominantly delaminations, which are confirmed via numerical analyses through high in-plane shear stresses levels, and via experimental analyses through stereoscopic micrographs.

Behavior of normal-strength recycled aggregate concrete filled steel tubes under combined loading

The use of recycled aggregate concrete (RAC) for the fill in concrete filled steel tube (CFST) members (RACFST members) is proposed as a practical structural application. An experimental study of RACFST members with normal-strength concrete under combined loading is summarized. Forty-eight columns and three beams in groups of 3 identical specimens were tested to failure. Study parameters included recycled coarse aggregate (RCA) replacement percentage, source of RCA, eccentricity, slenderness, and the steel to concrete area ratio. Experimental results are consistent with less than 3% scatter within each group. The maximum compressive load of the columns decreased modestly with increasing substitution level of RCA (up to 11.2%), and the structural effects of the recycled aggregate replacement on load capacity and initial stiffness are smaller than the corresponding changes in material properties. The source of RCA had little effect on the behavior of RACFST under combined loading for this test program, and the similar size grading and index of crushing obtained in the aggregates may have provided this benefit. These observations support the use of RACFST in structural engineering. Current CFST design provisions are compared to the RACFST test results, and the design recommendations for RACFSTs are presented.

A students' challenge for the estimation of the maximum compressive load of masonry prisms / Studentenwettbewerb zur Ermittlung der maximalen Druckfestigkeit von Mauerwerksprismen

AbstractThe paper presents the “IMC Students' Challenge” competition held in 2014, during the 9th International Masonry Conference, in Guimarães. The objective of the competition was to predict the maximum compressive load of two masonry prisms built of solid bricks, and of hollow blocks, with mortar joints. To increase the complexity of the problem, all prisms were tested under eccentric load. The students, who enthusiastically participated in the final laboratory tests, presented different approaches to estimate the maximum eccentric compressive force on masonry prisms. The challenge was a great experience, not only for students and conference participants, but also for sponsors and organizers.

Compressive Force Profile of High Biomass Erianthus Clones

Behaviour of plant material to mechanical compression depends on the physical properties of plant stalks and their resistance to compressive force. Rind with a high content of lignocellulosic fiber is a potential material for structural strength of the crop that participates in transfer of the loading stresses. The purpose of the study was to calculate mechanical properties of Erianthus arundinaceus cane with rind and without rind. Consequently, force deformation and stress and strain of the cane samples were studied which enumerate the basic essential information to determine the mechanical properties of cane under mechanical compression testing condition. Erianthus arundinaceus is a crop gaining momentum due to its potential for renewable energy value. The various parameters related to mechanical compression was studied using Universal Testing Machine (UTM). It was found that the clone IK76-93 × SF 06-48 yielded the maximum compression load. Maximum displacement force 9.04 kN was required to compress the Erianthus stem with rind, and the minimum displacement force was enabled at 5.13 kN for the clone IK76-81 × GC04-09. The clones without rind exhibited the maximum displacement force at 9.04 kN for the clone IK76-93 × SF 06-48, and the minimum was for the clone IK76-81 × GC04-09 at 3.86 kN. Information on the displacement profile of Erianthus clones gave a better understanding of the stem and rind behavior, and this would be helpful in designing crusher rollers for paper industry.

Lumbar vertebrae fracture injury risk in finite element reconstruction of CIREN and NASS frontal motor vehicle crashes

ABSTRACTIntroduction: The objective of this study was to reconstruct 4 real-world motor vehicle crashes (MVCs), 2 with lumbar vertebral fractures and 2 without vertebral fractures in order to elucidate the MVC and/or restraint variables that increase this injury risk.Methods: A finite element (FE) simplified vehicle model (SVM) was used in conjunction with a previously developed semi-automated tuning method to arrive at 4 SVMs that were tuned to mimic frontal crash responses of a 2006 Chevrolet Cobalt, 2012 Ford Escape, 2007 Hummer H3, and 2002 Chevrolet Cavalier. Real-world crashes in the first 2 vehicles resulted in lumbar vertebrae fractures, whereas the latter 2 did not. Once each SVM was tuned to its corresponding vehicle, the Total HUman Model for Safety (THUMS) v4.01 was positioned in 120 precrash configurations in each SVM by varying 5 parameters using a Latin hypercube design (LHD) of experiments: seat track position, seatback angle, steering column angle, steering column telescoping position, and d-ring height. For each case, the event data recorder (EDR) crash pulse was used to apply kinematic boundary conditions to the model. By analyzing cross-sectional vertebral loads, vertebral bending moments, and maximum principal strain and stress in both cortical and trabecular bone, injury metric response as a function of posture and restraint parameters was computed.Results: Tuning the SVM to specific vehicle models produced close matches between the simulated and experimental crash test responses for head, T6, and pelvis resultant acceleration; left and right femur loads; and shoulder and lap belt loads. Though vertebral load in the THUMS simulations was highly similar between injury cases and noninjury cases, the amount of bending moment was much higher for the injury cases. Seatback angle had a large effect on the maximum compressive load and bending moment in the lumbar spine, indicating the upward tilt of the seat pan in conjunction with precrash positioning may increase the likelihood of suffering lumbar injury even in frontal, planar MVCs.Conclusion: In conclusion, precrash positioning has a large effect on lumbar injury metrics. The lack of lumbar injury criteria in regulatory crash tests may have led to inadvertent design of seat pans that work to apply axial force to the spinal column during frontal crashes.

An Experimental Behaviour of Cellular Lightweight Concrete-Filled Steel Square Tube Columns under Axial Compression

The axial load behavior of cellular lightweight concrete-filled tube (CLCFT) columns subjected to concentric axial compression is experimentally investigated. In the study, the maximum compressive loads obtained from the experiment were compared with the values calculated using Eurocode 4 design equation. The dimension of the square column specimens 150 mm in width and 750 mm in height. The effects of the ultimate compressive strengths and wall thicknesses of the steel tubes were observed. A total of 24 specimens, including 18 CLCFT columns and 6 reference cellular lightweight concrete (CLC) columns, were tested under monotonic axial compression. From the tests, it was found that the response curves of the CLCFT columns have a linear elastic behavior up to approximately 80-90% of their maximum compressive load. The nonlinear behavior of the columns has a ductile-like with strain-softening type. Tests also showed that the maximum compressive load and ductility of the CLCFT columns are increased significantly compared to the reference columns, depending mainly on the ultimate compressive strength of the concrete and the wall thickness of the steel tube. In addition, good agreement was observed between the predicted values using the Eurocode 4 design equations for the composite column and the experimental results.

철도적용에서 곡형차량의 구조강도에 관한 연구

Stress tests were conducted in the carbody of the railroad car to check the structural strength of the body of the railroad car. The objective of this study was to evaluate safety of the carbody of a railroad car under the maximal strength. The carbody of rolling stock is a principal structure that supports major equipment of the underframe and the freight. Therefore, the strength evaluation of this structure is important. This study was carried out to analyze the structure of carbody and evaluate safety under maximum vertical load, compressive load, and torsional load. Accordingly, stress tests were conducted on the carbody to measure the stress on each of their parts. Before the load test, a structural-analysis program was used for the stress distribution analysis of the body structure.

An Experimental Study of Briquetting Process of Torrefied Rubber Seed Kernel and Palm Oil Shell.

Torrefaction process of biomass material is essential in converting them into biofuel with improved calorific value and physical strength. However, the production of torrefied biomass is loose, powdery, and nonuniform. One method of upgrading this material to improve their handling and combustion properties is by densification into briquettes of higher density than the original bulk density of the material. The effects of critical parameters of briquetting process that includes the type of biomass material used for torrefaction and briquetting, densification temperature, and composition of binder for torrefied biomass are studied and characterized. Starch is used as a binder in the study. The results showed that the briquette of torrefied rubber seed kernel (RSK) is better than torrefied palm oil shell (POS) in both calorific value and compressive strength. The best quality of briquettes is yielded from torrefied RSK at the ambient temperature of briquetting process with the composition of 60% water and 5% binder. The maximum compressive load for the briquettes of torrefied RSK is 141 N and the calorific value is 16 MJ/kg. Based on the economic evaluation analysis, the return of investment (ROI) for the mass production of both RSK and POS briquettes is estimated in 2-year period and the annual profit after payback was approximately 107,428.6 USD.