Stamina of a non-gasketed flange joint under combined internal pressure, axial and bending loading : an experimental study

The performance of a bolted flange joint is characterized mainly by its 'strength' and 'sealing capability'. A number of numerical and experimental studies have been conducted to study these characteristics under internal pressure loading conditions alone. However, limited work is found in the literature under conditions of combined internal pressure and axial loading. The effect of external, axial loading pressure being unknown, the optimal performance of the bolted flange joint cannot be achieved. Current design codes do not address the effects of axial loading on structural integrity and sealing ability. To study joint strength and sealing capability under combined loading conditions, an extensive experimental and numerical study of a non¬gasketed flange joint was carried out. Actual joint load capacity was determined at both design and test stages with the maximum external axial loading that can be applied for safe joint performance. Experimental and numerical results have been compared and overall joint performance and behaviour is discussed in detail

Stamina of a non-gasketed flange joint under combined internal pressure and axial loading

The performance of a bolted flange joint is characterized mainly by its 'strength' and 'sealing capability'. A number of numerical and experimental studies have been conducted to study these characteristics under internal pressure loading conditions alone. However, limited work is found in the literature under conditions of combined internal pressure and axial loading. The effect of external, axial loading pressure being unknown, the optimal performance of the bolted flange joint cannot be achieved. Current design codes do not address the effects of axial loading on structural integrity and sealing ability. To study joint strength and sealing capability under combined loading conditions, an extensive experimental and numerical study of a non-gasketed flange joint was carried out. Actual joint load capacity was determined at both design and test stages with the maximum external axial loading that can be applied for safe joint performance. Experimental and numerical results have been compared and overall joint performance and behaviour is discussed in detail

Loading on the Scapho-Trapezium-Trapezoid joint during gripping

The scapho-trapezium-trapezoid (STT) joint is believed to be highly vulnerable to wear and has been identified clinically as a high risk joint in arthritic patients. A theoretical model [1] of the load transfer through the wrist during gripping, suggests high activity in the STT ligaments in order to stabilize the carpus. During gripping complicated loading patterns are seen in the carpal bones and various intercarpal joints comprising the wrist joint. The aim was to investigate contact stresses at the STT joint in comparison to those occuring at the radiocarpal joint. Finite element model was created of the whole wrist joint with physiological loading conditions applied

Subchondral bone density distribution of the talus in clinically normal Labrador Retrievers

Background: Bones continually adapt their morphology to their load bearing function. At the level of the subchondral bone, the density distribution is highly correlated with the loading distribution of the joint. Therefore, subchondral bone density distribution can be used to study joint biomechanics non-invasively. In addition physiological and pathological joint loading is an important aspect of orthopaedic disease, and research focusing on joint biomechanics will benefit veterinary orthopaedics. This study was conducted to evaluate density distribution in the subchondral bone of the canine talus, as a parameter reflecting the long-term joint loading in the tarsocrural joint. Results: Two main density maxima were found, one proximally on the medial trochlear ridge and one distally on the lateral trochlear ridge. All joints showed very similar density distribution patterns and no significant differences were found in the localisation of the density maxima between left and right limbs and between dogs. Conclusions: Based on the density distribution the lateral trochlear ridge is most likely subjected to highest loads within the tarsocrural joint. The joint loading distribution is very similar between dogs of the same breed. In addition, the joint loading distribution supports previous suggestions of the important role of biomechanics in the development of OC lesions in the tarsus. Important benefits of computed tomographic osteoabsorptiometry (CTOAM), i.e. the possibility of in vivo imaging and temporal evaluation, make this technique a valuable addition to the field of veterinary orthopaedic research

Determination of load capacity of a nongasketed flange joint under combined internal pressure, axial and bending loading for safe strength and sealing

Performance of a bolted flange joint is characterized mainly due to its ‘strength’ and ‘sealing capability’. A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. A very limited work is found in literature under combined internal pressure and bending loading. Due to the ignorance of external loads i.e. bending and axial in addition to the internal pressure loading, an optimized performance of the bolted flange joint can not be achieved. The present design codes do not address the effects of combined loading on the structural integrity and sealing ability. To investigate joint strength and sealing capability under combined loading, an extensive comparative experimental and numerical study of a non-gasketed flange joint with two different taper angles on the flange surface and with different load combinations is carried out and overall joint performance and behavior is discussed. Actual joint load capacity is determined under both the design and proof test pressures with maximum additional external loading (axial and bending) that can be applied for safe joint performance

Upper Extremity Biomechanics of Children with Spinal Cord Injury during Wheelchair Mobility

While much work is being done evaluating the upper extremity joint dynamics of adult manual wheelchair propulsion, limited work has examined the pediatric population of manual wheelchair users. Our group used a custom pediatric biomechanical model to characterize the upper extremity joint dynamics of 12 children and adolescents with spinal cord injury (SCI) during wheelchair propulsion. Results show that loading appears to agree with that of adult manual wheelchair users, with the highest loading primarily seen at the glenohumeral joint. This is concerning due to the increased time of wheelchair use in the pediatric population and the impact of this loading during developmental years. This research may assist clinicians with improved mobility assessment methods, wheelchair prescription, training, and long-term care of children with orthopaedic disabilities

Stress distribution of secondary bending in single-lap bolted joints with dissimilar joining plates and plate types

Single-lap joints are an important class of bolted joint in the aerospace and civil engineering sectors. This type of joint is preferred as it can reduce weight and hence help to optimize fuel efficiency. However, bolted single-lap joints exhibit secondary bending due to eccentricity of the applied loads. Flexural of plates during tensile loading alters the contact regions in the single-lap joint significantly, resulting in more non-linear behaviour and a stress gradient across the plate thickness. 3-D bolted single-lap joint were modelled in ABAQUS CAE incorporating the effect of the bolt tension from application of a tightening torque. Current 3-D model used elastic properties based on smeared-out properties, the effect of joint construction is considered further by examining the stress in a composite-composite joint and comparing with a composite-steel joint. In a related investigation the effect of varying composite thickness in the composite-steel joints is also studied

A Critical Analysis of the Effects of Colello v. SEC on International Securities Law Enforcement Agreements

The load carrying capacity of interbre joints are one of the key entities for build-up of strength inpaper materials. In order to gain insight in how to tailor the macroscopic properties of such materialsby chemical and/or mechanical treatments at a microscopic level, direct measurement of individualbre{bre crosses are typically performed. However, the state of loading in the interbre joint, intesting of individual bre{bre crosses, is in general very complex and an increased understandingfor how to evaluate the mechanical properties of interbre joints is desirable. In Paper A, amethod for manufacturing and measuring the strength of isolated interbre joints is presented. Themethod is applied to investigate the strength of bre{bre crosses at two dierent modes of loading.Also, an investigation on the manufacturing conditions is presented. The strength distribution ofindividually prepared bre{bre crosses is characterized and it was found that the median strengthin a peeling type of loading was about 20% compared to samples tested in the conventional shearingtype of loading. In Paper B, a procedure for evaluating interbre joint strength measurementsin terms of resultant forces and moments in the interbre joint region is presented. The methodis applied to investigate the state of loading in bre{bre crosses tested in peeling and shearing,respectively. It is shown that for a typical interbre joint strength test, the load components otherthan shear, cannot in general be neglected and is strongly dependent on the structural geometry ofthe bre{bre crosses. In Paper C, four distinctly dierent load cases; peeling, shearing, tearingand a biaxial type of loading was tested mechanically and evaluated numerically in order to gainmore information on how interbre joints behave in dierent modes of loading. In Paper D, thein uence of a chemical additive on the interbre joint strength is investigated on the microscopic(joint) scale and correlated to the eect previously observed on the macroscopic (sheet) scale. Xraymicrotomography and image analysis was used to understand structural changes in the brousnetwork in terms of the number of interbre joints as well as the average interbre joint contact area.The results showed that the median interbre joint strength increased by 18% upon adsorption, andthat the polyelectrolyte increased the number of contacts between the bres as well as an increasedarea of contact. In Paper E, the damage behaviour of individual interbre joints is analyzed. Froman extensive number of mechanical tests, the typical damage behaviour is identied and a failurecriterion is used to study the in uence of failure properties to give indications on how to tailor thematerial to optimize the joint strength.En av de viktigaste mekanismerna for den lastbarande formagan hos pappersmaterial ar brottegenskapernahos berfogarna. For att eektivt skraddarsy sadana materials egenskaper genom kemiskoch/eller mekanisk behandling samt for att forsta hur sadana modieringar paverkar egenskapernapa en mikroskopisk niva ar provning av individuella ber-ber-kors en allmant anvand metod. Belastningeni en berfog vid sadan provning ar dock generellt komplicerad och ytterligare kunskapom hur berfogars mekaniska egenskaper skall utvarderas ar onskvard. I Artikel A, presenterasen metod for tillverkning samt mekanisk provning av isolerade ber-kors vid tva olika typer avbelastning. Vidare undersoks hur torktrycket, torkmetoden samt graden av malning inverkar pafogstyrkan. Resultaten visar att brottlasten for en globalt akande belastning var omkring 20 % avbrottlasten for prov utforda med den konventionella skjuvande belastningen samt att styrkan hosindividuellt tillverkade berkors ar fordelade enligt en Weibull fordelning. I Artikel B, presenterasen numerisk metod for utvardering av fogstyrke-matningar med avseende pa kraft- och momentresultanternai gransytan mellan brerna. Metoden anvands for att studera belastningsmoden hosber-kors i tva principiellt olika lastfall. Resultaten visar att for ett typiskt berfogsprov, kan intelastkomponenterna, vid sidan av skjuvning, generellt forsummas da de ar starkt beroende avber-korsets geometri. I Artikel C, jamfors fogstyrkematningar under fyra principiellt olika lastfall; akande, skjuvande, rivande samt biaxiellt. De experimentella last-forskjutningskurvorna, samtde beraknade lastmoderna anvands for att undersoka vilket tillskott pa information de foreslagnalastfallen kan ge i hansyn till fogstyrkan hos massabrer. I Artikel D, undersoks en polymers (somabsorberats pa berytorna) inverkan pa saval berniva som pa natverksniva. Fiberfogstyrkan matsexperimentellt och eekten av den kemiska tillsatsen jamfors pa mikroskopisk niva (ber-kors) medtidigare uppmatt eekt pa makroskopisk niva (ark). Rontgentomogra och bildanalys anvands foratt undersoka de strukturella skillnaderna som uppstar i de brosa natverken vid absorption av enpolyamin och resultaten visar att antalet berfogar per berlangdenhet samt att medelkontaktareanokade. Resultaten visar ocksa att medianen av berfogsstyrkan okade med 18 %. Dessa eekter sammantagetar anledningen till varfor polyaminer, sasom PAH, ar sa eektiva for att oka torrstyrkanhos pappersmaterial. I Artikel E, karakteriseras skadebeteendet hos individuella berfogar franett omfattande antal matningar. Ett brottkriterium infors i den numeriska utvarderingsmetoden foratt studera skadebeteendet. Kanslighetsanalys och inverkan av brottparametrarna studeras ocksafor att ge indikationer pa hur egenskaperna kan skraddarsys for att optimera berfogstyrkan.QC 20140527BiMaC Innovatio

Mechanical end joint system for connecting structural column elements

A mechanical end joint system is presented that eliminates the possibility of free movements between the joint halves during loading or vibration. Both node joint body (NJB) and column end joint body (CEJB) have cylindrical engaging ends. Each of these ends has an integral semicircular tongue and groove. The two joint halves are engaged transversely - the tongue of the NJB mating with the groove of the CEJB and vice versa. The joint system employs a spring loaded internal latch mechanism housed in the CEJB. During mating, this mechanism is pushed away from the NJB and enters the NJB when mating is completed. In order to lock the joint and add a preload across the tongue and groove faces, an operating ring collar is rotated through 45 deg causing an internal mechanism to compress a Belleville washer preload mechanism. This causes an equal and opposite force to be exerted on the latch bolt and the latch plunger. This force presses the two joint halves tightly together. In order to prevent inadvertent disassembly, a secondary lock is also engaged when the joint is closed. Plungers are carried in the operating ring collar. When the joint is closed, the plungers fall into tracks on the CEJB, which allows the joint to be opened only when the operating ring collar and plungers are pushed directly away from the joining end. One application of this invention is the rapid assembly and disassembly of diverse skeletal framework structures which is extremely important in many projects involving the exploration of space

Analysis of externally loaded bolted joints : analytical, computational and experimental study

The behaviour of a simple single-bolted-joint under tensile separating loads is analysed using conventional analytical methods, a finite element approach and experimental techniques. The variation in bolt force with external load predicted by the finite element analysis conforms well to the experimental results. It is demonstrated that certain detailed features such thread interaction do not need to be modelled to ensure useful results. Behaviour during the pre-loading phase of use agrees with previous long-standing studies. However, the pre-loading analysis does not carry over to the stage when external loading is applied, as is normally assumed and it is shown that the current, conventional analytical methods substantially over-predict the proportion of the external load carried by the bolt. The basic reason for this is shown to be related to the non-linear variation in contact conditions between the clamped members during the external loading stage